Volume 71, Issue 10 - Special Issue: Dedicated to Professor Gerhard Erker on the occasion of his 70th birthday

Cu II and Au III chlorido complexes bearing the bis(NHC) carbazolide pincer ligand (bimca) were synthesized by transmetallation from the respective lithium complex [Li(bimca)] (NHC=N-heterocyclic carbene). In the case of copper, two different molecular structures were obtained depending on the copper source. With Cu(II) chloride the paramagnetic mononuclear [Cu(bimca)Cl] complex is formed and has been characterized by EPR spectroscopy and X-ray structure analysis, while copper(I) chloride leads under oxidation to a dinuclear structure in which two cationic [Cu II (bimca)] moieties are bridged by one chlorido ligand. The positive charge is compensated by the [CuCl 2 ] − counter ion, as proven by X-ray structure analysis. Transmetallation of [Li(bimca)] with AuCl 3 leads to the [Au(bimca)Cl] + complex with a tetrachloridoaurate counter ion.

Dimeric anilidolithium (ArHNLi·Et 2 O) 2 (Ar=2,6- i Pr 2 C 6 H 3 ) reacted with zirconium tetrachloride in THF to give the heterometallic zirconium–lithium complex [(Et 2 O) 2 Li(μ-Cl) 2 (ArHN)(ArN=)Zr(μ-Cl)] 2 ( C1 ) and with titanium tetrachloride in toluene to give the titanium complex [(ArN=)TiCl 2 ·(Et 2 O) 2 ] ( C2 ) each in good isolated yields. Their molecular structures in the solid state were confirmed by X-ray diffraction analysis. Upon activation with methylaluminoxane, both arylimido zirconium and titanium complexes exhibited good catalytic activities toward ethylene polymerization.

The europium(III) complex 1 -Cl 3 ( S,S -2,2′-(((1,10-phenanthroline-2,9-diyl)bis(methanylylidene))bis(azanylylidene))bis(3-methylbutanamide)europiumtrichloride) undergoes, only in the presence of the amino acid tryptophan, a change of emission at 615 nm. In the presence of few equivalents of tryptophan, emission of the europium complex is enhanced while it disappears upon addition of large amounts. This behavior can be assigned to displacement of the sensitizing phenanthroline ligand of 1 -Cl 2 •Trp in the latter case.

In presence of 2,2,6,6-tetramethylpiperidinium ([ TMPH ] + ) chlorotris(pentafluorophenyl)borate ([ TMPH ] + [ClB(C 6 F 5 ) 3 ] − , 3 ), phenylacetylene undergoes an unusual cyclotrimerization-rearrangement leading to tris(pentafluorophenyl)(3,4,5-triphenylphenyl)borate anion ( 1 ) as a minor product which can be isolated and purified in a form of salts [ 1·(TMPH) n ·Cl ( n –1) ] ( n =3 or 5). A variable temperature and concentration NMR spectroscopy study of 3 in CDCl 3 unambiguously demonstrated its ability to liberate free B(C 6 F 5 ) 3 , which initiates cyclotrimerization and guides rearrangements towards formation of the tetraarylborate anion 1 . For the previously studied “spectator” reaction between phenylacetylene and B(C 6 F 5 ) 3 in CDCl 3 , 1 H, 19 F, and 11 B NMR-spectral evidence of the (C 6 F 5 ) 3 B − –C(H)=C + Ph zwitterionic intermediate of the 1,1-carboboration reaction has been demonstrated. The crystal structures of [ 1·(TMPH) 3 ·Cl 2 ], the salt 3 , and a 1:1 adduct of 1,3,5-tris(4-fluorophenyl)benzene and 2,4,6-tris(pentafluorophenyl)-1,3,5,2,4,6-trioxatriborinane ( 2 ) have been established by X-ray diffraction analysis.

Treatment of the Al/P-based frustrated Lewis pair (FLP) Mes 2 P–C(Al t Bu 2 )=C(H)-Ph ( 1 ) with benzophenone afforded the simple 1:1 adduct ( 4 ) with a O=CPh 2 molecule coordinated to the aluminum atom by an Al←O donor-acceptor bond. Steric repulsion may prevent an interaction between the electrophilic carbonyl carbon atom and the Lewis-basic phosphorus atom. 4 is unstable in solution at room temperature, the coordination to aluminium increases the polarisation of the carbonyl group and favours its reduction. As suggested by quantum chemical calculations, a C–H bond of a t Bu group approaches the electrophilic center and facilitates β-hydride elimination with the release of isobutene and the formation of an Al–OCHPh 2 ligation. An intact O=CPh 2 molecule completes the coordination sphere of the metal atom ( 5 ). The second t Bu group at aluminium reacts similarly by the selective formation of an Al(OCHPh 2 ) 2 moiety ( 6 ). The thermodynamics of adduct formation and the mechanism of the hydride shift have been evaluated by quantum chemical DFT calculations.

The synthesis and structure of [Ag(9-methyl-6-furylpurine)(NO 3 )] n are reported. The title compound represents a rare example of a purine derivative metalated at all three endocyclic nitrogen atoms. It forms a two-dimensional coordination polymer comprising 14-membered trinuclear metallacycles. Density functional theory calculations helped to understand the metal-binding behavior of the 6-furylpurine moiety by showing the silver(I)-binding affinities of all three nitrogen donor atoms to be essentially identical under aqueous conditions.

The morphan system (2-azabicyclo[3.3.1]nonane) as a substructure of morphine is of major interest in medicinal chemistry. Herein, the synthesis of morphan derivatives with additional substituents at the propano bridge is reported. In order to avoid the isolation of the smelly and volatile nitrile 6 and the very polar primary amine 9 , an efficient one-pot, three-step sequential transformation of the mesylate 5 into amides 10 was developed. The key step of the synthesis was the stereoselective intramolecular opening of the epoxides 11a – d leading to the exo -configured 8-hydroxymorphans 12a – d . The configuration of the exo -configured hydroxymorphan 12d bearing the κ- and σ-pharmacophoric 3,4-dichlorophenylacetyl moiety was inverted by oxidation and stereoselective reduction. An X-ray crystal structure analysis of the benzamide 12c confirmed the relative configuration of the hydroxymorphans 12a – d and 14d .

The monoclinic intermediate-valent gallide CeCoGa decomposes under high-pressure (HP) (9.5 GPa) high-temperature (HT) (1470 K) conditions into the Laves phases CeCo 0.58 Ga 1.42 (MgCu 2 type), CeCo 0.72 Ga 1.28 (MgZn 2 type; major product phase), and CeCo 2 (MgCu 2 type). The structures of the ternary Laves phases were refined from single crystal X-ray diffractometer data: Fd 3̅ m , a =778.3(1) pm, wR 2=0.0310, 63 F 2 values, five variables for CeCo 0.58(3) Ga 1.42(3) and P 6 3 / mmc , a =547.24(5), c =858.76(7) pm, wR 2=0.1009, 195 F 2 values, 13 variables for CeCo 0.72(1) Ga 1.28(1) . Partial substitution of cobalt by gallium leads to a significant increase of the distances within the tetrahedral network: 253 pm Co–Co in CeCo 2 as compared to 275 pm in CeCo 0.58(3) Ga 1.42(3) and 265–277 pm in CeCo 0.72(1) Ga 1.28(1) . The crystal chemical consequences are briefly discussed.

Reaction of 2-chloro- N -(methoxymethyl)benzimidazole 1 with zerovalent group 10 metal complexes in the presence of an additional proton source yielded, via an oxidative addition of the C2–Cl bond, complexes with a protic NH,NR-substituted (R=methoxymethyl) benzimidazolin-2-ylidene ligand. The oxidative addition of 1 to Ni 0 and Pd 0 complexes proceeded with the exclusive formation of the trans -configured complexes trans -[ 2 ]BF 4 and trans -[ 3 ]BF 4 , respectively. Contrary to this observation, the reaction of 1 with a more substitution inert Pt 0 complex leads, depending on the reaction temperature, to a mixture of cis-/trans -[ 4 ]BF 4 or exclusively to trans -[ 4 ]BF 4 . The molecular structures of all three trans -configured complexes were determined.

Herein we present a study of the influence of the ancillary ligand on the photophysical properties of Pt(II) complexes with a symmetric tridentate luminophore. Starting from a previously used bulky triphenylphosphane (PPh 3 ) as the monodentate ancillary ligand, progressively smaller ancillary ligands were introduced, namely a PPh 2 Me and a PPhMe 2 and finally compared with a planar 4-amylpyridine. We observed that the emission wavelength of the monomer was not influenced by the monodentate ligand, and that excimer formation only occurs for the fully planar complex. Surprisingly, intermolecular deactivation pathways can be largely suppressed even with the smallest phosphane. This knowledge is important for the design and realization of triplet emitters for optoelectronic devices.