Volume 68, Issue 5-6

This review describes the various ways of functionalizing the pyridine scaffold using either directed metalation or halogen/metal exchange. Deprotonation can be accomplished with different lithium amides or alkyllithium reagents at low temperature. Milder conditions and higher functional group tolerance can be achieved by using ate-bases with different metals (Cd, Mg, Zn) or TMP (2,2,6,6- tetramethylpiperidyl) metal reagents (metal=Mg, Zn, Zr). With alkyllithium reagents it is also possible, by carefully adjusting the reaction conditions, to perform bromine/lithium exchange reactions. Organomagnesium reagents, like iPrMgX (X=Br, Cl LiCl), may be used for exchanging more sensitive iodinated or brominated pyridines Graphical Abstract Review. Regioselective Functionalization of Pyridines using a Directed Metalation or a Halogen/Metal Exchange

In this article, we discuss how fluorescence microscopy techniques are used to investigate important characteristics of porous silica materials. We start with a discussion of the synthesis, formation mechanism and functionalization of these materials. We then give an introduction to single molecule microscopy and show how this technique can be used to gain deeper insights into some defining properties of porous silica, such as pore structure, host-guest interactions and diffusion dynamics. We also provide examples from the literature demonstrating how fluorescence microscopy is used for elucidating important aspects of porous silica materials and heterogeneous catalysis, e. g. diffusion properties, reactivity, morphology, intergrowth, accessibility, and catalyst deactivation. Finally, a short outlook on the scope of porous silica hosts in drug delivery applications is given Graphical Abstract Review. Fluorescence Microscopy Studies of Porous Silica Materials

The reactivity of the N-heterocyclic carbene (NHC) 1,3-bis(2,6-diisopropylphenyl)imidazol-2- ylidene towards dichlorosilane H 2 SiCl 2 , bis(trifluoromethanesulfonato)silane H 2 Si(OTf) 2 (OTf = OSO 2 CF 3 ), and silyl trifluoromethanesulfonate H 3 SiOTf has been investigated. It turned out that the coordination of the NHC ligand can occur stepwise to form the three neutral compounds (NHC)SiH 2 Cl 2 (1), (NHC)2SiH 2 Cl 2 (2), (NHC)SiH 2 (OTf) 2 (3), as well as the two ion pairs [(NHC)SiH 3 ] + (OTf-) (4) and [(NHC) 2 SiH 3 ] + (OTf - ) (5); the latter represent the first NHC adducts of the parent silylium cation (H 3 Si + ). The multinuclear NMR and IR spectroscopic data of the products reflect the characteristics of four-, five-, and six-coordinate silane complexes. All new compounds were structurally characterized by single-crystal X-ray diffraction analyses Graphical Abstract Coordination of N-Heterocyclic Carbene to H 2 SiX 2 (X = Cl, OTf) and H 3 SiOTf (OTf = OSO 2 CF 3 ): Synthesis of Donor-stabilized Parent Silylium Salts with Four- and Five-coordinate Silicon Atoms

The adduct of (3-MeC 6 H 4 ) 3 B 3 O 3 with an N-heterocyclic carbene (NHC=1,3-diethyl-4,5- dimethylimidazol-2-ylidene) was prepared by reacting 2.5 equiv. of 3-methylphenylboronic acid with 1 equiv. of the NHC. This reaction shows a novel carbene-facilitated condensation of substituted phenylboronic acid monomers. The structure of the compound (3-MeC 6 H 4 ) 3 B 3 O 3 (NHC) (1) has been characterized by 1H NMR spectroscopy, elemental analysis, and single-crystal X-ray diffraction studies Graphical Abstract N-Heterocyclic Carbene-facilated Condensation of 3-Methylphenylboronic Acid to the Boroxine

Two methylene-bridged bis(imidazolium) salts [H 4 L 1 ](PF 6 ) 2 and [H 4 L 2 ](PF 6 ) 2 with appended amide groups have been synthesized which, after deprotonation, may serve as potentially tetradentate ligands providing two bis(imidazole-2-ylidene) and two amide donors. Using [H 4 L 1 ](PF 6 ) 2 , a square-planar nickel(II) complex [NiL 1 ] and a six-coordinate bis(ligand) iron(II) complex [Fe(HL 1 ) 2 ] have been isolated and structurally characterized. Their low-spin states have been confirmed spectroscopically, and their redox properties have been studied by cyclic voltammetry. Oxidations are metal-centered to give Ni III and Fe III species, respectively Graphical Abstract Nickel(II) and Iron(II) Complexes with Tetradentate NHC/Amide Hybrid Ligands

Gold complex [AuCl(NHC)] (NHC=N,N0-dipropylbenzimidazolin-2-ylidene) 1 undergoes facile substitution reactions at the gold(I) center. Treatment of 1 with anionic phenylacetylide or thiophenolate led to the neutral gold complexes 2 and 3, respectively. The cationic gold complexes [Au(NHC)(pyridine)](BF 4 ) [4]BF 4 and [Au 2 (NHC) 2 (4,4'-bipyridine)](BF 4 ) 2 [5](BF 4 ) 2 were obtained via abstraction of the chloro ligand from 1 and reaction with the appropriate amine. Reaction of 1 with AgBF 4 in the presence of PPh 3 instead of an amine led to an inseparable product mixture of the mixed NHC=PPh 3 complex [6]BF 4 , the dicarbene complex [Au(NHC) 2 ]BF 4 , [7]BF 4 , and [Au(PPh 3 ) 2 ]BF 4 , [8]BF 4 . Crystals of 2 and [6]BF 4 were obtained, and X-ray diffraction structure analyses revealed that the gold(I) atoms are coordinated in a linear fashion by the NHC and the co-ligand Graphical Abstract Ligand Exchange at a Gold(I) Carbene Complex

The reaction between (tht)AuCl (tht = tetrahydrothiophene) and KCN leads to gold(I) cyanide. This can be treated with liquid amines or azaaromatics L to give crystalline molecular complexes LAuCN, the first complexes of the type (amine)cyanogold(I): L = cyclohexylamine, isobutylamine, isopropylamine, diethylamine, morpholine, piperidine, pyrrolidine, 2,4-lutidine, 3,5-lutidine, and 4- picoline. The cyclohexylamine complex was also obtained as the adduct LauCN L and the pyrrolidine complex in the ionic form [L 2 Au]+ [Au(CN) 2 ] - . Two polymorphs of the 3,5-lutidine complex were obtained. Ethylenediamine gave the 2:1 complex L(AuCN) 2 . Several of the structures were difficult to refine because of pseudosymmetry (e. g. polar axes). The packing diagrams were analyzed in terms of Au-Au contacts and NH .... N hydrogen bonds. As proof of the principle that the method is also suitable for other ligands, the complex with t-butyldiisopropylphosphane was synthesized and structurally characterized Graphical Abstract Aminkomplexe des Goldes, Teil 7: Pseudosymmetrie bei Aminkomplexen des Gold(I)-cyanids [1] / Amine Complexes of Gold, Part 7: Pseudosymmetry in Amine Complexes of Gold(I) Cyanide

Two cyclic alkyl(aryl)boranes, a 1-bora-indane derivative 1, and a tricyclic derivative 4, containing the boron atom in a six-membered ring, were structurally characterized by NMR techniques in solution. The solid-state structure of the 1-bora-indane 1 was determined by X-ray crystallography. The reactivity of these cyclic alkyl(aryl)boranes towards monoalkynyltin compounds, Me 3 Sn-C≡C-Me and Me 3 Sn-C C-Fc (Fc=ferrocenyl), was studied using multinuclear magnetic resonance methods ( 1 H, 11 B, 13 C, 119 Sn NMR). Novel alkenylboranes were formed by 1,1-carboboration reactions. This process involves an expansion of both five- and six-membered rings. Insertion into the respective B-C(aryl) bond was preferred with high selectivity. In the case of the six-membered ring in 4, the ring expansion to seven-membered rings proved to be readily reversible, and the thermodynamically stable reaction products were formed by ring contraction and concomitant transfer of the exocyclic B- n Pr group Graphical Abstract Cyclic Alkyl(aryl)boranes for 1,1-Carboboration of Monoalkynyltin Compounds

Treatment of sterically highly shielded terminal alkynes, H-C≡C-aryl, with dialkylaluminium and dialkylgallium hydrides, R 2 E-H, afforded by hydrogen release dimeric dialkylelement alkynides with a four-membered E 2 C 2 heterocycle independent of the bulk of the aryl groups. A rare example of a monomeric alkynylaluminium compound was only obtained with very bulky CH(SiMe 3 ) 2 groups attached to the metal atoms and by salt elimination reaction. The steric shielding by the bulky aryl groups did not prevent condensation reactions. Hydroalumination of 1-(trimethylsilyl)-2-(2,6- dimethylphenyl)ethyne using Me 2 Al-H resulted in a divinyl compound by elimination of trimethylaluminium Graphical Abstract Hydroalumination versus Deprotonation of Alkynes with Sterically Demanding Substituents

The metathesis reaction of strontium diiodide [(thf) 5 SrI 2 ] with K[N(Ph)iPr] in THF yields [(thf) 4 Sr{N(Ph)iPr} 2 ] (1). Ligand exchange reactions with 1,2-dimethoxyethane (DME), tetramethylethylenediamine (TMEDA), and pentamethyldiethylenetriamine (PMDETA) allow the isolation of the corresponding adducts [(dme) 2 Sr{N(Ph)iPr} 2 ] (2), [(tmeda)(thf)Sr{N(Ph)iPr} 2 ] (3) and [(pmdeta)Sr{N(Ph)iPr} 2 ] (4), respectively. Magnesiation of N-isopropylaniline with dibutylmagnesium in THF leads to the formation of [(thf) 2 Mg{N(Ph)iPr} 2 ] (5). A similar reaction in TMEDA gives nearly insoluble crystalline [(tmeda)Mg{N(Ph)iPr} 2 ] (7), whereas the mother liquor contains heteroleptic [(tmeda)(nBu)Mg{N(Ph)iPr}] (6). Magnesiation of N-isopropylaniline in 2,2,5,5-tetramethyltetrahydrofuran (Me 4 thf) yields [(M e 4thf)Mg{N(Ph)iPr} 2 ] (8) with a threecoordinate metal center. In hydrocarbons this complex loses the bulky ether base, and the solvent-free dimer [Mg{N(Ph)iPr} 2 ] 2 (9) can be isolated. Reaction of this complex with 1,2- dimethoxyethane or metalation of N-isopropylaniline with dibutylmagnesium in DME yield the dme adduct, [(dme)Mg{N(Ph)iPr} 2 ] (10). The crystal structures show that the nitrogen atoms of the magnesium-bound N-isopropylanilide ions are in planar environments whereas strontium-bound N-isopropylanilide ions show rather short contacts between the alkaline earth metal and the ipsocarbon atoms of the phenyl groups leading to a pyramidalization of the coordination of the nitrogen atoms Graphical Abstract Synthesis and Characterization of Strontium Bis(N-isopropylanilide) and Comparison with the Lighter Magnesium and Calcium Congeners

The principal structural characteristics of softwood (spruce) were replicated in CaCO 3 and CaO on various levels of hierarchy from the macroscopic to the submicron scale. Positive replicas were obtained by infiltrating pretreated softwood templates with a Ca(OCOOCH 3 ) 2 precursor solution which hydrolyzed into CaCO 3 nanoparticles. They reproduce the hierarchical porous structure of the wood template. Calcination at temperatures from 350 to 900 °C yields calcite as the main polymorph. Mechanical stability of the replica is optimized when the specimen is calcined at 900 °C Graphical Abstract Preparation of CaCO 3 and CaO Replicas Retaining the Hierarchical Structure of SpruceWood

The nucleophilic carbene 1,3-diisopropyl-4,5-dimethyl-2,3-dihydroimidazol-2-ylidene (7) captures nitrous oxide under formation of both syn- (8) and anti-1,3-diisopropyl-4,5-imidazolium diazotate (9). The syn-isomer is the thermodynamically more stable form. As shown by X-ray crystallography, the two isomers are statistically distributed in the crystalline state Graphical Abstract The 1 : 1 Adduct of 1,3-Diisopropyl-4,5-dimethyl-2,3-dihydroimidazol-2- ylidene and Nitrous Oxide

Recrystallization of silver pentacyanocyclopentadienide Ag[C 5 (CN) 5 ] from N,N-dimethylformamide (DMF) gives the polymeric 1:1 complex [Ag{C 5 (CN) 5 }(DMF)] (1). The Ag + cation is coordinated by three N atoms of three different [C 5 (CN) 5 ] - anions and two O atoms of two DMF molecules. Each [C 5 (CN) 5 ] - is coordinated via three neighboring CN groups to three different Ag + ions, while each DMF molecule bridges two Ag + ions via its O atom. Treatment of NiCl2 6H 2 O, CoCl 2 6H 2 O or ZnCl 2 with Ag[C 5 (CN) 5 ] in DMF gives the DMF complexes [M(DMF) 6 ][C 5 (CN) 5 ] 2 (M=Ni, 2; Co, 3; Zn, 4). The complexes 2 and 3 were characterized by X-ray diffraction and show octahedral [M(DMF) 6 ] 2+ cations with O-coordinated DMF molecules. The [C 5 (CN) 5 ]- anions show ideal pentagonal symmetry Graphical Abstract Coordination Chemistry of Polynitriles, I. Syntheses and Crystal Structures of [Ag(PCC)(DMF)], [Ni(DMF) 6 ](PCC) 2 and [Co(DMF) 6 ](PCC) 2 (PCC = [C 5 (CN) 5 ] - , DMF = N,N-Dimethylformamide) [1]

As a siderophore analog, the tripodal tris(benzene-o-dithiol)-functionalized ligand H 6 -5, has been synthesized in four steps including the reaction of 1,3,5-(triaminomethyl)-2,4,6-triethylbenzene and 2,3-bis(isopropylmercapto)benzoyl chloride followed by removal of the S-protecting groups. Reaction of compound H 6 -5 with [Ti(OPr) 4 ] in the presence of (NEt 4 )Cl leads to the formation of complex (NEt 4 ) 2 [Ti(5)] featuring three bidentate benzene-o-dithiolato donors from one ligand coordinated to the metal center. An X-ray diffraction structure analysis with crystals of (NEt 4 ) 2 [Ti(5)] DMF has shown that the coordination geometry at the metal center is best described as distorted trigonalprismatic with a twist angle of ϕ av = 18:5°. Graphical Abstract Synthesis and Coordination Chemistry of a Tris(benzene-o-dithiolato)- functionalized Ligand as a Siderophore Analog

The synthesis and characterization including the crystal structure of the dinuclear palladium( II) complex [(k-S,S’)-{N(SPPh 2 ) 2 }Pd(m-{k 2 -S'',S'''})-{N(SPPh 2 ) 2 }PdCl 2 ] (1) are reported. Compound 1 was obtained from the reaction of [PdCl 2 (COD)] (COD=1,5-cyclooctadiene) and HN(SPPh 2 ) 2 in a 1:1 molar ratio in CH 2 Cl 2 . The {N(SPPh 2 ) 2 } - ligands act both as bridging and/or terminally chelating units Graphical Abstract A Dinuclear Palladium(II) Complex of the {N(SPPh 2 ) 2 } - Ligand – Synthesis and Structure

Reaction of equimolar amounts of [Bi(OtBu) 3 ] and [Cp 2 ReH] yields [Cp 2 Re-Bi(OtBu) 2 ], 1, when the reaction time is kept short. Treatment of [Bi{OCH(CF 3 ) 2 } 3 (thf)] 2 with four equivalents of [Cp 2 ReH] leads to the heterotrinuclear complex [(Cp 2 Re) 2 Bi{OCH(CF 3 ) 2 }], 4, with two Re- Bi bonds. A complex with a Bi-Fe bond was obtained in the reaction between [Cp(CO) 2 Fe] 2 and [Bi(OAc)3]: [Cp(CO) 2 Fe-Bi(OAc) 2 ], 5, was formed and found to crystallize as a dimer. The structures of 1 and 4 were also investigated Graphical Abstract Heterometallic Complexes with Rhenium- and Iron-Bismuth Bonds

A water-soluble, crystalline Au 9 cluster compound stabilized with sodium (m-sulfonatophenyl) diphenylphosphine (TPPMSNa) was obtained during the NaBH 4 reduction of [Au(TPPMSNa)Cl] H 2 O in ethanol. Characterization by optical extinction spectroscopy, singlecrystal X-ray diffraction in combination with energy dispersive X-ray diffraction led to the preliminary formula Na (8-x) [Au 9 (TPPMS)8]Cl(3-x) nH 2 O (0 ≤ x ≤ 3, n ≈ 16) with the cluster core in crown conformation. 31 P{ 1 H} nuclear magnetic resonance spectroscopy revealed one singlet at 57:3 ppm. This is the first example where gold clusters stabilized by TPPMSNa formed crystals which where suitable for core structure determination Graphical Abstract Isolation, Optical Properties and Core Structure of a Water-soluble, Phosphine-stabilized [Au 9 ] 3+ Cluster

The new copper chalcogenide cluster [Cu 40 Se 16 (S-C 6 H 4 -CN) 8 (dppm)8] (1) with nitrile groups in the organic ligand shell has been synthesized and characterized by single-crystal X-ray diffraction and IR spectroscopy. The arrangement of the chalcogen atoms in 1 is similar to a close packing and is best described as two parallel layers with an ab stacking sequence. The resulting structure is a rare example of a disc-like cluster molecule Graphical Abstract [Cu 40 Se 16 (S-C 6 H 4 -CN) 8 (dppm) 8 ]: A Disc-like Copper Cluster with a Nitrile-functionalized Ligand Shell

The compounds Ca(Fe 1-x Nix) 2 As 2 with the tetragonal ThCr 2 Si 2 -type structure (space group I4=mmm) show a continuous transition of the interlayer As-As distances from a non-bonding state in CaFe 2 As 2 (d As-As =313 pm) to single-bonded As 2 dimers in CaNi 2 As 2 (d As-As =260 pm). Magnetic measurements have revealed weak ferromagnetism which develops near the composition Ca(Fe 0:5 Ni 0:5 ) 2 As 2 , while the compounds with lower and higher nickel concentrations are both Pauli-paramagnetic. DFT band structure calculations have shown that the As 2 dimer formation is a consequence of weaker metal-metal bonding in the MAs 4/4 layers (M=Fe 1-x Ni x ) of the Ni-rich compounds, and depends not on depopulation or shift of As-As σ antibonding states as previously suggested. Our results also show that the ferromagnetism of Ca(Fe 0:5 Ni 0:5 ) 2 As 2 and related compounds like SrCo 2 (Ge 0:5 P 0:5 ) 2 is not as recently suggested induced by dimer breaking, but arises from the high density of states generated by the transition metal 3d bands near the Fermi level without contribution from dimers Graphical Abstract Ferromagnetism and the Formation of Interlayer As2 Dimers in Ca(Fe 1-x Ni x )2As 2

Ionic compounds containing the polyoxomolybdate anion [Mo 6 O 19 ] 2 - and [(n-C 4 H 9 ) 4 P] + (tetrabutylphosphonium), [(n-C 4 H 9 ) 3 P(n-C 14 H 29 )] + (tributyl (tetradecyl)phosphonium), [Bmim] + (1- butyl-3-methylimidazolium) and [Dbmim]+ (1,2-dimethyl-3-butylimidazolium) cations were prepared and characterized, including the determination of three of the solid state structures by singlecrystal X-ray diffraction. These compounds were applied as catalysts for the epoxidation of olefins with urea hydrogen peroxide (UHP) as oxidant in the ionic liquid [Bmim]PF 6 . Additionally, the oxidation of sulfides to sulfoxides with hydrogen peroxide (H 2 O 2 ) in several solvents was investigated. The polyoxomolybdate catalysts showed a good performance for epoxidation of olefins as well as for oxidation of sulfides. Furthermore, the catalysts can be recycled several times in oxidation reactions. We present this methodology for the oxidation reaction in a simple, economically, technically, and environmentally benign manner Graphical Abstract Oxidation Reactions Catalyzed by Polyoxomolybdate Salts

A series of air- and water-stable imidazolium perrhenate-based room-temperature ionic liquids [(RT)ILs] of the type [Cnmim][ReO 4 ] (Cnmim = 1-C n H 2n+1 -3-methylimidazolium, n = 2, 4, 5, 6, 8, 10, 12) have been synthesized and characterized by 1 H and 13 C NMR spectroscopy, IR spectroscopy, electrospray ionization mass spectrometry (ESI-MS), and elemental analysis (EA). The effect of the variation of the alkyl chain length on physical properties such as melting point, thermal stability, density, and conductivity was examined Graphical Abstract Synthesis and Characterization of Imidazolium Perrhenate Ionic Liquids

The new compound [Mn(dien)2][Mn(dien)SbS 4 ] 2 (dien=diethylenetriamine) was synthesized under solvothermal conditions. It crystallizes in the non-centrosymmetric monoclinic space group P2 1 with a=7.5736(5), b=19.1081(16), c=13.1174(11) Å, b =90:022(9) , V =1898.3(3) Å 3 , and Z =2. The crystal structure is composed of one [Mn(dien) 2 ] 2+ cation and an anionic chain composed of [SbS 4 ] 3- anions and [Mn(dien) 2 ] 2+ cations. The [SbS 4 ] 3- anions connect [Mn(dien) 2 ] 2+ ions in a μ 2 -fashion to form an undulated {[Mn(dien)SbS 4 ]} -2 chain running along [001]. The Mn 2+ ions in the chain are in a rare distorted rectangular pyramidal coordination environment with 3 N and 1 S atom forming the base and one S atom being located at the apex of the pyramid. The anionic chains and the cations alternate along [010]. Several relatively strong intra- and inter-chain N-H-S bonding interactions are observed. From the Raman spectrum the reduction of the ideal T d symmetry of the [SbS 4 ] 3- anions is obvious because more resonances occur than expected for the undistorted geometry Graphical Abstract Infinite Anionic Chains Formed by Alternating Bidentately Acting [SbS4] 3- Anions and [Mn(dien)] 2+ Complexes in the Compound [Mn(dien) 2 ][Mn(dien)SbS 4 ] 2

Two new silver vanadate arsenates, Ag 2 VAsO 6 and Ag 6 V 2 As 2 O 13 , have been prepared applying high oxygen pressure syntheses in stainless-steel autoclaves. Ag 2 VAsO 6 crystallizes in space group P1 with unit cell parameters a=639.1(1), b=646.1(1), c=706.6(1) pm, α =116.105(3), ß =91.759(4), γ = 90:067(4)°, and Z =2 (R 1 =0.058, 3935 independent reflections). The structure consists of AsO 4 tetrahedra and VO 6 octahedra which are linked to form two-dimensional 2 ¥ [VAsO 6 ] 2- polyanions, separated by silver cations. Ag 6 V 2 As 2 O 13 (C2=c, a=1895.9(2), b=536.40(6), c=1308:5(2) pm, ß =113:578(2)°, Z =4; R 1 =0.030, 2571 independent reflections) displays as primary building units AsO 4 tetrahedra and VO 5 trigonal bipyramids which are condensed by sharing edges to one-dimensional 1 ¥ [V 2 As 2 O 13 ] 6- ladder-like strands, set apart by the silver cations. These heteropolyanions are without precedent Graphical Abstract Novel Polyanionic Topologies in Ag 2 VAsO 6 and Ag 6 V 2 As 2 O 13

The lanthanoid(III) bromide ortho-oxomolybdates(VI) LnBr[MoO 4 ] (Ln = Pr, Nd, Sm, Gd - Lu) crystallize triclinically in the space group P1 (a=686 - 689, b=713 - 741, c=1066 - 1121 pm, a =103 - 106, b =107 - 108, g = 92 - 95°) with Z =4. The crystal structure contains two crystallographically distinguishable Ln 3+ cations, each one with a coordination number of seven plus one. (Ln1) 3+ is surrounded by three bromide and four plus one oxide anions, while for (Ln2) 3+ just one bromide and six plus one oxide anions belong to the coordination sphere. Considering the smallest lanthanoids, however, the distances to the farthest anions increase so much that their contribution to the coordination spheres becomes negligible in both cases. The polyhedra around (Ln1) 3+ are connected to each other via common edges, which consist of two crystallographically identical Br - anions (Br1). Furthermore, the common structure of the LnBr[MoO 4 ] series contains two crystallographically different, discrete [MoO 4 ] 2- ortho-oxomolybdate(VI) tetrahedra. Two plus one oxygen atoms of each [(Mo1)O 4 ] 2- unit are used to interconnect the polyhedra around (Ln1) 3+ and (Ln2) 3+ together with one Br - anion (Br2). The connection between two polyhedra around (Ln2) 3+ is generated exclusively by two plus one oxygen atoms of two [(Mo2)O 4 ] 2- anions. The complete structural arrangement can be considered as a bundle of primitively packed 1 ¥ {LnBr[MoO 4 ]} chains with two alternating motifs of linkage, which are running parallel along [012]. Graphical Abstract Syntheses and Crystal Structures of the Bromide-derivatized Lanthanoid(III) Ortho-Oxomolybdates(VI) LnBr[MoO 4 ] (Ln = Pr, Nd, Sm, Gd– Lu)

Small single crystals of the Sm5Ge4-type (space group Pnma) germanides RE 2 Nb 3 Ge 4 (RE = Sc, Y, Gd-Er, Lu) and Sc 2 Ta 3 Ge 4 were synthesized by arc-melting of the respective elements. The samples were characterized by powder and single-crystal X-ray diffraction. In all structures, except for Sc 2.04 Nb 2.96 Ge 4 and Sc 2.19 Ta 2.81 Ge 4 , the rare earth and niobium atoms show full ordering on the three crystallographically independent samarium sites of the Sm 5 Ge 4 type. Two sites with coordination number 6 are occupied by niobium, while the slightly larger site with coordination number 7 is filled with the rare earth element. Small homogeneity ranges with RE=Nb and RE=Ta mixing can be expected for all compounds. The ordered substitution of two rare earth sites by niobium or tantalum has drastic effects on the coordination number and chemical bonding. This was studied for the pair Y 5 Ge 4 /Y 2 Nb 3 Ge 4 . Electronic structure calculations show larger charge transfer from yttrium to germanium for Y 5 Ge 4 , contrary to Y 2 Nb 3 Ge 4 which shows stronger covalent bonding due to the presence of Nb replacing Y at two sites Graphical Abstract Single-crystal Data of Ternary Germanides RE 2 Nb 3 Ge 4 (RE = Sc, Y, Gd–Er, Lu) and Sc 2 Ta 3 Ge 4 with Ordered Sm 5 Ge 4 -type Structure

The rare-earth fluoride borates RE 4 B 4 O 11 F 2 ( RE = Pr, Nd) were obtained in a Walker-type multianvil device from the corresponding rare-earth oxides and fluorides, and boron oxide. Pr 4 B 4 O 11 F 2 was obtained under high-pressure/high-temperature conditions of 8.5 GPa=1150°C, and Nd 4 B 4 O 11 F 2 at 8 GPa and 1300°C. The single-crystal structure determinations revealed that both compounds are isotypic to RE 4 B 4 O 11 F 2 ( RE = Eu, Gd, Dy), crystallizing in the space group C 2= c ( Z = 4) with the parameters a = 1397.3(3), b = 472.78(9), c = 1400.2(3) pm, β = 91:1(1)°, V = 0.9248(3) nm3, R 1 = 0.0444, and wR 2 = 0.0539 (all data) for Pr 4 B 4 O 11 F 2 , and a = 1389.1(3), b = 471.2(1), c = 1394.4(3) pm, β = 91:1(1)°, V = 0.9125(3) nm 3 , R 1 = 0.0286, and wR 2 = 0.0601 (all data) for Nd 4 B 4 O 11 F 2 . The structure type of Gd 4 B 4 O 11 F 2 contains BO 4 tetrahedra as well as BO 3 groups connected via common corners. Here, we report about the crystallographic characterization of both compounds in comparison to the isotypic phases and discuss their IR spectra. Graphical Abstract RE 4 B 4 O 11 F 2 (RE = Pr, Nd): Two New Rare-earth Fluoride Borates Isotypic to Gd 4 B 4 O 11 F 2

Reactions of cadmium(II) thio- and selenocyanate with 4-acetylpyridine in different molar ratios and in different solvents always lead to the formation of compounds of composition Cd(NCS)2(4- acetylpyridine) 2 (Cd1-I) and Cd(NCSe) 2 (4-acetylpyridine)2 (Cd2). Both compounds are isotypic and crystallize in the monoclinic space group C2/c. In their crystal structures the Cd cations are coordinated by two N-bonded 4-acetylpyridine ligands as well as two N- and two S/Se-bonded thio- or selenocyanato anions within a slightly distorted octahedral geometry. The Cd cations are linked into chains by pairwise μ-1,3-coordinating thio- or selenocyanato anions. In one reaction single crystals of a second polymorphic modification of composition Cd(NCS) 2 (4-acetylpyridine) 2 (Cd1-II) were obtained by accident. This modification crystallizes monoclinically in space group P2 1 /c, exhibits the same topology of the coordination network as in Cd1-I and Cd2 but a different arrangement of the chains in the crystal. Similar investigations with Zn(II) have revealed that only one compound of composition Zn(NCS) 2 (4-acetylpyridine)2 can be prepared that crystallizes in the triclinic space group P1. Its structure consists of discrete complexes in which the Zn(II) cations are tetrahedrally coordinated. A corresponding selenocyanato coordination compound could not be prepared Graphical Abstract Synthesis, Crystal Structures and Polymorphism of New Cadmium and Zinc Thio- and Selenocyanato Coordination Compounds with 4-Acetylpyridine as N-Donor Ligand

Novel Sn(IV) complexes with the guanidine-quinoline hybrid ligand DMEGqu are reported. With SnCl 4 , SnBr 4 , Me 2 SnCl 2 , Me 2 SnBr 2 , and the 3,5-di-tert-butyl-catecholate coligand complexes with different donor sets were synthesized. Four of these tin compounds have been modelled by density functional theory. Additionally, a tetranuclear Sn(IV) oxocluster with a novel structure motif, a distorted hetero-adamantane with bridging oxido and hydroxido ligands, is presented Graphical Abstract Novel Tin(IV) Complexes with the Hybrid Guanidine Ligand DMEGqu

Bis(dimesitylphosphanyl)butadiyne (14) reacts with B(C 6 F 5 ) 3 by a 1,1-carboboration sequence. The selective attack at a single phosphanyl-alkyne moiety is observed. First a phosphirenium-borate zwitterion 15 is formed at r. t. Thermolysis (80 °C) results in the E-selective formation of the 1,1- carboboration product, the frustrated Lewis pair (FLP) E-16, which upon heating to 160 °C eventually undergoes isomerization followed by an internal nucleophilic aromatic substitution reaction to give the product 17 featuring a -B(F)(C 6 F 5 ) 2 substituent at the five-membered P-heterocycle. Finally, the FLP E-16 was reacted with n-butylisocyanide to yield the five-membered heterocyclic product 18, formed by P,B addition to the isonitrile carbon atom. Compounds 14, 15, 17, and 18 were characterized by X-ray crystal structure analyses Graphical Abstract Facile 1,1-Carboboration Reaction of a Diarylphosphino-substituted Conjugated Diyne with Tris(pentafluorophenyl)borane

The close genetic relationship of the mushrooms Retiboletus griseus and R. nigerrimus is supported by the occurrence of the orange-yellow retiboletic acid, resp. its methyl ester, in both species. The structures of these highly substituted pulvinic acid derivatives have been elucidated by spectroscopic investigations. R. nigerrimus also contains two N-protocatechuyl-L-phenylalaninol derivatives, nigerrimin A and B, the first reported occurrence of such compounds in nature. Their configuration was established by the synthesis of nigerrimin B Graphical Abstract New Pulvinic Acid and Phenylalaninol Derivatives from the Mushrooms Retiboletus griseus and R. nigerrimus

A brightly red fluorescent 1-hydroxyperylene bisimide was prepared by a nucleophilic aromatic displacement reaction. The deprotonation of the hydroxy group shifts the absorption and the strong fluorescence into the NIR. A selected medium promotes an ESPT mechanism and induces a large Stokes’ shift of nearly 200 nm in the NIR Graphical Abstract NIR Absorption of Perylene Dyes and Fluorescence with Large Stokes’ Shift by Simple Deprotonation

The solid-state structure of chlorido[2-(N,N,N',N'-tetramethylamidinio)ethynido]silver (3), obtained by C(sp)-metalation of N,N,N',N'-tetramethyl-propiolamidinium chloride with silver(I) oxide, has been determined by X-ray diffraction analysis. A comparison of bond lengths in the propiolamidinium moiety with those of the two genuine propiolamidinium salts 4 and 5, as well as with data for the isolated N,N,N',N'-tetramethyl-propiolamidinium cation obtained by quantum-chemical calculations, has been made. It can be concluded that complex 3 is better described as a (tetramethylamidinio) ethynyl than as a 3,3-bis(dimethylamino)allenylidene silver complex Graphical Abstract Molecular and Crystal Structure of Chlorido[2-(N,N,N',N'- tetramethylamidinio)ethynido]silver

The nucleophile-specific parameters N and s N , as defined by the linear free energy relationship log k = s N (N+E) (J. Am. Chem. Soc. 2001, 123, 9500 - 9512), were determined for five imines 1a-e by studying the kinetics of their reactions with benzhydrylium ions in dichloromethane solution at 20 °C. These parameters allowed us to include representative Schiff bases into our comprehensive nucleophilicity scale and compare their reactivities with those of other N-nucleophiles Graphical Abstract Nucleophilic Reactivities of Schiff Bases

Interaction of 6-amino-1-ethyl-4-oxoquinoline-3-carboxylic ester (7) with chloral hydrate and hydroxylamine hydrochloride gave the corresponding isonitroso-acetamido derivative 8 which, upon treatment with concentrated sulfuric acid, was converted regioselectively into 1,2,9-trioxopyrrolo[ 3,2- f ]quinoline-8-carboxylic acid (3). This novel tricyclic system was isolated in good yield as a stable hydrate 3H. Structural assignments of the new compounds are based on microanalytical and spectral (MS and NMR) data Graphical Abstract Synthesis of 6-Ethyl-1,2,9-trioxopyrrolo[3,2-f ]quinoline-8-carboxylic Acid

The first macrocycle incorporating two ruthenium sandwich complexes has been synthesised. Key step is a cyclodimerisation by double etherification of a p-chlorophenylalanine-derived [RuCp*] + complex. Silica-based cation exchange chromatography allowed the separation of dicationic diastereomers. Assignment of the relative configurations was possible by X-ray structure determination. Partial demetalation in acetonitrile proceeded in high yield by irradiation in the presence of biphenyl Graphical Abstract Synthesis of a 30-Membered Macrocycle Incorporating Two Ruthenium Sandwich Complexes

Nitrogen-rich polymers were synthesized by radical polymerization using the reaction of 5- aminotetrazole with methacryloyl chloride and acryloyl chloride, respectively. The nitrogen content of poly(methacrylamidotetrazole) and poly(acrylamidotetrazole), as well as the energetic character of these compounds was increased by nitration of the amido moiety. The products remained however insensitive and had a very good thermal stability. All substances were characterized by using vibrational spectroscopy (IR), mass spectrometry, elemental analysis, as well as multinuclear NMR spectroscopy. Additionally, the impact and friction sensitivities were determined by BAM standards, and also the sensitivity against electrostatic discharge was studied. The energetic properties were investigated by bomb-calorimetric measurements and calculations with the EXPLO5 software, and the thermal stability was investigated by differential scanning calorimetry. All compounds are thermally highly stable materials. The high stability of the polymers towards impact and friction and the good energetic character makes these polymers promising candidates for applications as environmentally friendly nitrogen-rich polymers Graphical Abstract Novel Insensitive Energetic Nitrogen-rich Polymers Based on Tetrazoles

The molecular structures and relative ratios of the two conformers (anti and gauche) of HCCCH 2 ONO 2 detected in the gas phase at room temperature have been determined by electron diffraction. The results are discussed on the basis of quantum chemical calculations. The molecular structures of (NO 2 ) 3 CCH 2 C≡CCH 2 C(NO 2 ) 3 and (NO 2 ) 3 CCH 3 have been determined by X-ray diffraction. A 109 Ag NMR study was performed for silver trinitromethanide Ag[C(NO 2 ) 3 ] in various polar solvents. Graphical Abstract Structures of Energetic Acetylene Derivatives HC≡CCH 2 ONO 2 , (NO 2 ) 3 CCH 2 C≡CCH 2 C(NO 2 ) 3 and Trinitroethane, (NO 2 ) 3 CCH 3

Treatment of solutions of Na 4 Sn 4 in liquid ammonia with CuMes (Mes=mesityl) and 18-crown-6 afforded crystals of the composition Na 4 [Sn 4 ] (NH 3 ) 13 . The structure features anionic units {Na 7 [Sn 4 ] 2 } and separate Na cations, both fully solvated by ammonia molecules Graphical Abstract First Incorporation of the Tetrahedral [Sn 4 ] 4- Cluster into a Discrete Solvate Na 4 [Sn 4 ] (NH 3 ) 13 from Solutions of Na 4 Sn 4 in Liquid Ammonia

The reaction of 2,2,2-nitrilotriacetic acid with phosphorus pentachloride furnished 2,2,2-nitrilotriacetyl chloride (1), a useful chemical intermediate for various further reactions. The compound has been fully characterized by multinuclear NMR spectroscopy, vibrational analysis (IR and Raman), mass spectrometry and elemental analysis. Furthermore, the crystal structure of 1 has been determined and discussed thoroughly, showing a NC 3 unit with an unusual, nearly planar configuration Graphical Abstract Synthesis and Structure of 2,2,2- Nitrilotriacetyl Chloride with a Flat NC3 Pyramide

Two isomers of the [Co(tren)(D-Glc1A1,2H- 2 -K 2 O 1,2 )] + (1) chelate are formed in equal parts in the reaction of [Co(tren)Cl 2 ]Cl and sodium gluconate. In contrast, the gluconate’s 2-amino-2-deoxy derivative glucosaminate formed a single isomer of [Co(tren)(D-Glc1A2N1H- 1 -k 2 N,O 2 )] 2+ (2). Crystals of the OC-6-34 isomer of 1, [1a]PF 6 H 2 O, showed the support of the metal-binding site by intramolecular hydrogen bonds. Due to the inertness of the cobalt(III) chelates, spectroscopy on redissolved crystals of [1a]PF 6 H 2 O allowed the separation of the two 13C NMR signal sets of the isomeric mixture. In a DFT approach, a small energy difference explained the formation of two isomers in the case of the gluconate. A larger difference was obtained for the glucosaminate, in line with the known rules for the stereospecific amino acid-Co(tren) chelation Graphical Abstract Cobalt(III)-Binding of Gluconate and 2-Amino-2-Deoxy-Gluconate

The synthesis and structural characterization of the complex [Ru 2 (μ-Cl)(μ-P t Bu 2 )(μ-dppa)(CO) 4 ] (4, dppa = Ph 2 PN(H)PPh 2 ) are reported. The title compound and two other related complexes were obtained in high yields by the reaction of the coordinatively unsaturated species [Ru 2 (μ-H)(μ-P t Bu 2 )(μ-PˆP)(CO) 4 ] (PˆP = dppa, 3; PˆP =Ph2PN(Ph)PPh 2 , 5; PˆP =Ph 2 PN(CH 2 Ph)PPh 2 , 6) with carbon tetrachloride. Single crystals of 4 grown from dichloromethane-acetone have been analyzed by X-ray crystallography Graphical Abstract Activation of C–Cl Bonds: Synthesis and Structural Characterization of [Ru 2 (μ-Cl)(μ-PtBu 2 )(μ- Ph 2 PN(H)PPh 2 )(CO) 4 ]

The first base-stabilized iodoborylene platinum complex was prepared through the addition of 4-picoline (4-Pic) to a suspension of an iodo-bridged binuclear iodoboryl complex. An X-ray structure determination of the title compound has characterized the molecular structure as cis-[Pt{BI(4- Pic)}I 2 (PCy 3 )]. The bond lengths lie in the expected range for neutral, base-stabilized borylene complexes. The strong trans influence of the borylene moiety is reflected in the longer Pt-1 distance for the iodo ligand opposite the borylene, compared to that opposite the phosphine ligand Graphical Abstract A Base-stabilized Iodoborylene Complex of Platinum(II)