Band 56, Heft 11

The crystalline phase of triphenyl phosphite P(OC 6 H 5 ) 3 was investigated by means of 31 P solid-state NMR and X-ray diffraction in a temperature range between 170 K and its melting point (T m = 293 K). ID MAS NMR spectra exhibit one sharp central resonance indicating only one crystallographically unique molecule in the unit cell. A theoretical analysis concerning the shape of 2D exchange spectra for 1 = 1 /2 nuclei is presented. It is shown that if the exchange is caused by radio-frequency driven spin-diffusion, this technique allows to discriminate rotational symmetry elements in crystalline solids. Used on crystalline triphenyl phosphite, 3-fold symmetry could be revealed clearly. Structure determination based on X-ray single crystal diffraction data collected at 191 K shows that triphenyl phosphite crystallises in hexagonal metric with space group R3̅(wR 2 = 8.3%, Z = 18) and one molecule in the asymmetric unit. This result is in excellent agreement with the NMR spectroscopic data. The lattice parameters at 200 K were determined to a = 37.887(1) and c = 5.7567(2) Å (V = 7156(1) Å 3 ) by refining an X- ray powder-diffraction pattern. The structure of triphenylphosphite can be described as a close rod packing. The rods are formed by ecliptically arranged triphenylphosphite molecules. Due to the 3-fold rotoinversion axis the orientation of molecules in neighboured rods is antiparallel.

The reactions of t BuN = VCl 2 · DME with LiX (X = NH t Bu, NR 2 , OSiPh 3 , SR, Alkyl, Cp) have been studied. LiNH t Bu and LiCH 3 furnish the binuclear diamagnetic tert-butylimido-vanadium( IV) compounds [(μ-N t Bu) 2 V 2 X 4 ]; in all other cases only the vanadium(V) compounds t BuN=VX 3 and t BuN=VCpCl 2 formed by disproportionation reactions of vanadium(IV) can be isolated. The syntheses of various mononuclear amido tert-butylimido-vanadium(V) complexes as well as of the binuclear complexes [μ-N t Bu) 2 V 2 (N t Bu) 2 Cl 2 ] and [(μ-0)V 2 (N t Bu) 2 Cp 2 Cl 2 ] are also described. All compounds obtained have been characterized by 51 V NMR spectroscopy. t BuN=V(OMe) 3 was investigated by X-ray diffraction analysis; the molecular structure has been found to be that of a binuclear vanadium(V) complex with two bridging methoxo ligands.

In the 1-azonia-acenaphthene salts 6b and 9, the N + -C peri bond is modestly elongated. While no clear-cut influence of the peri-stress is obvious, incorporation of C peri in a triarylmethyl structure has a bond-lengthening effect. However, the stretching forces are insufficient to restore the ideal geometry of the naphthalene skeleton.

[Co(NH 3 ) 6 ]ClCO 3 crystallizes in the cubic space group P2 1 3(No. 198)witha = 1000,5(2)pm, V EZ = 1001,4(3) · 10 6 pm 3 , Z = 4. Structural features are discrete [Co(NH 3 ) 6 ] 3+ , CO 3 2- and Cl - ions, connected by N-H···O and N-H···Cl bonds. The site symmetry of the carbonate group is C 3 , but vibrational spectroscopy shows that the CO 3 2- group is planar with local symmetry D 3h .

[Cu 3 (L) 3 ].3(C1O 4 ) (LH = l,3-diaminopropan-2-ol) was synthesized and its crystal structure determined. It crystallizes in the triclinic space group P1̅ with a = 10.504(2), b = 10.856(2), c = 12.519(2) Å, a = 74.41(1), ß = 70.60(1), γ = 63.60(1)°, V = 1193.6(3) Å 3 , Z = 2. The structure consists of trimeric [Cu 3 (L) 3 ] +3 units and three perchlorate anions in the asymmetric unit. In the compound three copper(II) ions are linked by 1,3-diamino-2-propanol molecules in such a way that an almost equilateral triangle is formed. The coordination spheres of the three copper(II) ions are slightly different from each other. The coordination geometry of Cu1 is a distorted square pyramid, and that of Cu2 is almost square planar while that of Cu3 is tetrahedrally distorted square planar. The copper(II) centers are separated by average 3.481(2) Å and antiferromagnetically coupled (-J = 100 cm -1 ), which follows from temperature- dependent magnetic susceptibility measurements in the temperature range 4.4 to 299 K. The average Cu-O-Cu angle is 128.1(1)° in the super-exchange pathway. As the temperature is increased, the magnetic moment rises from 1.41 μ B at 4.4 K to 2.22 μ B at 299 K. In the X (T ) curve no characteristic maximum was observed. The magnetic super-exchange interaction for the title compound is due to the effective overlap of the magnetic orbitals (d x²-y² ) with orbitals of bridging alkoxide oxygen atoms

[Cu 2 (L 3 )(3,5-prz)] (L 3 = 1,3-bis(2-hydroxy-4-methoxybenzylideneamino)-propan-2-ol) (3) was synthesized and its crystal structure determined. The compound consists of discrete binuclear units, in which copper atoms are linked by the alkoxide oxygen atom of the ligand and the pyrazolate nitrogen atoms. Variable-temperature magnetic susceptibility measurements for a powdered sample of the complex were carried out in the temperature range 4.4 - 308 K and analysed to obtain values of the parameter J in the exchange Hamiltonian H = -2JS 1 -S 2 . Recently, the dicopper(II) complexes [Cu 2 (L 1 )(3,5-prz)] (L 1 = 1,3-bis(2-hydroxy-1-napthylideneamino)- propan-2-ol) (1) and [Cu 2 (L 2 )(3,5-prz)], (L 2 = 1,3-bis(2-hydroxy-5-chlorosalicylideneamino)- propan-2-ol) (2) were reported. These compounds show antiferromagnetic behaviour (-2J: 444 cm -1 for 1 164 cm -1 for 2, and 472 cm -1 for 3). The strength of the super-exchange interaction (-2J) of 2 is much less than that of 1 and 3, a result which is difficult to explain in terms of structural factors on the basis of widely accepted criteria. The differences in the magnetic behaviour have been rationalized in terms of the bridging ligand orbital complementary / countercomplementary concept.

The thermal catalytic hydrosilylation of 1,3-butadiene (1), trans-2-methyl-1,3-pentadiene (2), 2,3-dimethyl-1,3-butadiene (3), and isoprene (4), with triethylsilane were studied in the presence of M(CO) 3 (o-xylene) (M = Cr, Mo, W) complexes in polar and nonpolar solvents such as tetrahydrofuran, hexane and toluene. Mo(CO) 3 (o-xylene) was found to be the only active catalyst for the hydrosilylation of 3 with triethylsilane, which gave 1-triethylsilyl-2,3-dimethyl- 2-butene (3a). as hydrosilylated product in tetrahydrofuran. The product was identified by means of 1 H and 13 C-NMR and GLC. The same catalyst, Mo(CO) 3 (o-xylene), decomposed to Mo(CO) 6 without giving hydrosilylated products of 1, 2 and 4 in tetrahydrofuran. M(CO) 3 (o-xylene) (M = Cr, Mo, W) complexes were found to be stable for about 6 h in hexane and toluene, and showed no catalytic activity for the hydrosilylation of 1, 2, 3 and 4.

The title compounds were prepared by arc-melting cold-pressed pellets of the elemental components. They crystallize with a tetragonal structure already reported for CeCr 2 Si 2 C. It was refined from single-crystal X-ray data of PrCr 2 S 2 C: P4/mmm, a - 402.2( 1) pm, c = 535.2(1) pm, Z = 1, R = 0.012 for 252 structure factors and 10 variable parameters. Magnetic susceptibility measurements with a SQUID magnetometer indicate Pauli paramagnetism for YCr 2 Si 2 C, while CeC 2 Si 2 C shows mixed valent behavior. The carbon atoms in the structure of these compounds are isolated from each other. The silicon atoms form pairs with a Si-Si distance of 245.3 pm, somewhat greater than the single-bond distance of 235.2 pm in elemental silicon. Together with the chromium atoms, the silicon pairs and carbon atoms form a three-dimensionally infinite polyanion, which has some similarity with the polyanions found in several related tetragonal structures, e.g., the structures of ThCr 2 Si 2 and LuNi 2 B 2 C.

Orthorhombic single crystals of CsCu 3 Dy 2 S 5 (a = 397.54(4), b = 1414.8(1), c = 1685.7(2) pm) and CsCu 3 Er 2 S 5 (a = 394.82(4), b= 1410.9(1), c = 1667.2(2) pm; both Cmcm, Z = 4) are obtained as by-products (pale yellow or pink transparent needles) in attempts to synthesize CuMS 2 (M = Dy and Er) through the oxidation of elemental copper, dysprosium and erbium, respectively, with sulfur (molar ratios: 1:1:2 ) in the presence of equimolar amounts of cesium chloride (CsCl) as fluxing agent at 900 °C within fourteen days from torch-sealed evacuated silica tubes. Their crystal structure contains octahedral [MS 6 ] 9- units (d(M-S) = 269 - 282 pm) which share edges and vertices to form layers 2 ∞ {(M 2 S 5 ) 4- } parallel (010). These are three-dimensionally interconnected along [010] by two crystallographically different Cu + cations in tetrahedral coordination of S 2- anions (d(Cu-S) = 227 - 269 pm) according to 3 ∞ {(Cu 3 M 2 S 5 ) - }. Thereby a likewise layered substructure 2 ∞ {(Cu 3 S 5 ) 7- } is formed parallel (010) by edge- and vertexlinking of all [CuS 4 ] 7- tetrahedra. Large channels within the 3 ∞ {(Cu 3 M 2 S 5 ) - } network spread along [100] and suit well to take up the highly coordinated Cs + cations, which are surrounded by eight plus one S 2- anions at distances between 340 and 358 pm (8x) with the ninth ligand 420 - 421 pm apart in the shape of (2+1)-fold capped trigonal prisms.

Lewis acid-base adducts between simple phosphines have been structurally characterized for the first time in the form of (Me 3 P)PBr 3 (1) and (Me 3 P)PBr 2 Bz′ (2; Bz′ = 3,5-dimethylbenzyl). On the basis of its solid-state structure the bonding situation in 1 may be described as intermediate between a neutral donor-acceptor complex containing hypervalent phosphorus(III) and an ion pair, according to the resonance formulae Me 3 P → PBr 3 ↔ [Me 3 P-PBr 2 ] + Br - . The weak (incomplete) bond formation to the third bromine atom clearly reflects the reluctance of trivalent phosphorus to accommodate more than four electron pairs in its valence shell. (Crystal data for 1: monoclinic P2 1 /n, a = 7.142(3), b = 16.844(2), c = 8.139(4) Å, ß = 106.24(2)°, Z = 4). As a result of the inferior acceptor properties of PBr 2 Bz′ as compared to PBr 3 , 2 has more ion pair character [Me 3 P-PBrBz′] + Br - than 1. (Crystal data for 2: orthorhombic P 2 1 2 1 2 1, a = 7.063(2), b = 8.578(2), c = 25.158(4) Å, Z = 4). Both compounds have short P-P bonds (1: 2.264(2); 2: 2.236(2) Å). The results are compared with previous IR/Raman and NMR investigations on 1 : 1 and 2 : 1 adducts between organophosphines (as donors) and phosphorus trihalides (as acceptors).

Lewis acid-base adducts between NMe 3 , tmeda (N ,N ,N′ ,N′-tetramethylethylenediamine), and 1.4-dimethylpiperazine as donors and PBr 3 as acceptor have been prepared and structurally characterized. NMe 3 and tmeda form 1:1 adducts (Me 3 N)PBr 3 (1) and (tmeda)PBr 3 (2), respectively, while 1,4-dimethylpiperazine adds 2 molecules of PBr 3 leading to [(1,4-dimethylpiperazine)( PBr 3 ) 2 ] (3). Adduct 2 is found in two modifications 2a and 2b with different crystal and molecular structures. (Crystal data of 1: monoclinic P2 1 /n, a = 5.983(3), b = 10.821(2), c = 13.877(5) Å, ß = 99.70(2)°, Z = 4. 2a: monoclinic P2 1 /c, a = 7.891(1), b = 12.826(1), c = 12.218(2) Å ,ß = 102.162(6)°, Z = 4. 2b: monoclinic P2 1 /n, a = 11.687(2), b = 8.375(1), c = 12.668(1) Å, ß = 102.74(1)°, Z = 4. 3: monoclinic P2 1 /c, a = 6.383(3), b = 16.36(3), c = 8.407(3) Å , ß = 101.49(2)°, Z= 2). The molecular structures of 1 and 2 indicate a partially ionic character with a strongly bonded amine and one (1 ) or two (2 ) weakly bonded bromine atoms. In 2 the donor tmeda is bonded through both nitrogen atoms to one phosphorus atom. In 3 the 1,4-dimethylpiperazine ring is in chair conformation, the methyl and PBr 3 substituents being in equatorial and axial positions, respectively. Due to axial-axial repulsion the N-P donor-acceptor bonds are long while the P-Br bonds are rather uniform in length.

Aryl formates 4a-u, 6 , 8 , 10, 12, 14, 16, 18, 20, 22, 24, 26 are prepared by formylation of hydroxyarenes 3a-u, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25 with N,N-diformylacetamide (1) or triformamide (2), respectively, in fairly good yields. The reactions can be catalyzed by sodium diformamide or praseodymium(III) triflate. The thiolformate 28 was obtained analogously from 1-thionaphthol (27).

The aromatic hydroxyaldehydes 3a-3g, 5a-5f, 8 , 10 can be prepared by the action of BCl 3 , BBr 3 or trifluoromethanesulfonic acid, on the aryl formates 1a-1f, 4a-e, 7, 9 via Fries rearrangement. BBr 3 is more effective than BCl 3 . The activating ability of BBr 3 can be improved by addition of FeCl 3 . Rearrangements which are induced by trifluoromethanesulfonic acid can give rise to the formations of regioisomers, which might be different from the products formed when the reaction is performed with Lewis acids. The yields of the aldehydes are lowered by subsequent condensation reactions. This view was confirmed by the isolation of a condensation product, which was characterized as a dibenzo[a,j]xanthene derivative 6 by crystal structure analysis. For the Fries rearrangement of formyl groups a new mechanism is proposed. 2-Hydroxy-1-naphthaldehyde 5c can be obtained in good yield from formic acid, BBr 3 , and 2 -naphthol.

The moisture-sensitive title compounds were obtained in good yields by treating the corresponding silver salts AgN(SO 2 R) 2 with the thiocarbamoyl chloride Me 2 NC(S)Cl in acetonitrile. In the NMR solution spectra of the novel thioureas, as recorded at room temperature for 13 C and up to 120 °C for 1 H, the Me 2 N group invariably gives rise to two distinct resonances, reflecting unusually high barriers to rotation about the C(S)-NMe 2 bond. The crystal structure of the ditosyl compound (triclinic, space group P1̅, X-ray diffraction at -130 °C) contains two independent molecules A and B, in which the bond lengths and angles are nearly identical, whereas the conformations exhibit pronounced discrepancies. The amide N and thiocarbonyl C atoms have trigonal-planar environments, but the S -N -S planes are strikingly rotated into approximately perpendicular orientations relative to the planar C 2 N-C(S)-N moieties. Other remarkable features of the molecular structures are the exceedingly long C(S)-NS 2 bonds [mean: 145.4(3) pm] and the concomitantly short C -S and C(S)-NC 2 bonds [mean values: 164.8(2), 132.6(3) pm]. The packing is governed by a three-dimensional system of weak hydrogen bonds and may be viewed as a self-clathrate, in which (B) 2 dimers constructed from C-H···S=C interactions are inserted as guest species into parallel tunnels between (A) ∞ tapes based upon short C-H···O=S contacts.

The (silylethynyl)- and the (tolylethinyl)-hydrazines 1a and 1b react with aryl isocyanates 2a-e and arylsulfonyl isocyanates 2f,g to form the corresponding substituted 3-arylimino-(or arylsulfonylimino-) 1,1,2-trimethyl-5-oxopyrazolidinium-4-ides 3a-h. The silyl group in the 4-position can be replaced by a hydrogen atom (formation of 6a-e). Heating of 6d in toluene induced the unequivocal transformation of the betaine to an isomer, the spectrocopic data of which are in concordance with those of the 4-quinolone derivative 7. Aroyl isocyanates 8 react in a [4+2]cycloaddition with la to furnish the 1,3-oxazin-4-ones 9a and b. The stannylated ynehydrazine 1c adds the cumulenic system of an aryl isocyanate (2d) across the C sp -Sn single bond, and trimethylstannyl .N-(p-chlorophenyl)-3-(trimethylhydrazino)propiolimidate 10 is isolated. With two molecules of 2d the hydantoin derivative 11 is formed.

The molecular nickel complexes trans-diazido-tetrakis(pyrazole)nickel(II) and trans-diazido- tetrakis(3-methylpyrazole)nickel(II) feature terminal monohapto-bound azide ligands. The pyrazole (pyr) ring planes are aligned along the N azide -Ni-N azide axis by intramolecular N-H···N azide bonds. The crystal packing is controlled by π-stacking between both pyrazole rings and azide ligands, N-H···N azide hydrogen bonds, and intermolecular N-H-π pyr and C-H···N/π azide interactions.

Various fluorosubstituted benzoylchlorides 1a-c are transformed into the corresponding acylpyridinium triflates 2a-c by one equivalent of the reagent pair 4-dimethyl-aminopyridine/ trimethylsilyltriflate (DMAP/TMSOTf). Due to the combined electrostatic and mesomeric effect of the acylpyridinium function, fluorine substituents in o- and p-positions can be subsequently substituted with a pyridinio group by additional equivalents of DMAP/ TMSOTf via an S N Ar mechanism. Whereas the p-substitution product can be isolated as the highly electrophilic dication salt 3b, the corresponding mono- and bis-orthosubstituted polycation salts 3a and 3c are transformed under the reaction conditions to the 7-azoniafluorenone derivatives 4a,c by a novel cyclo-acylation. Structural and electrochemical data of these compounds are presented.

The complexes cis-[Pd(PMSA) 2 Cl 2 ] cis-[Pt(PMSA) 2 X 2 ], trans-[Pt(PMSA) 2 I 2 ] and [Pt(PMSA) 4 ]Cl 2 (PMSA = N-3-pyridinylmethanesulfonamide; X = Cl, Br, I) have been synthesized and characterized by elemental analysis, molar electric conductivity, IR and 1 H NMR spectra. A detailed assignment of the IR spectra (4000-150 cm -1 ) of the complexes, supported by an approximate normal coordinate analysis, has been performed. The complexes are of square-planar type and the PMSA ligand is coordinated via the pyridine nitrogen atom.

A facile approach to cis- and trans-2-(l-hydroxymethyl)vinyl-1-vinylcyclohexan-1-ols and to the corresponding cyclopentane, cycloheptane, and cyclooctane derivatives has been developed, starting from cycloalkanones involving the key steps of Rupe and Claisen orthoester rearrangements. The formation of intervening products could be explained by allylic strain and π-stacking, respectively.

The dicationic 2,2-biimidazolyl derivative 5 has been obtained from the imidazolium salt 3 and the carbene 4 in good yield. The presence of the carbene 4 and its unstable dimer 7 were detected by NMR in the reduction product of 5 with potassium. The crystal structure of 5·H 2 O is reported.

The solid state reaction of KCl, NbCl 5 and Nb powder at 760 °C yielded black crystals of KNb 6 Cl 15 . The structure of the compound has been determined using single-crystal X-ray methods. KNb 6 Cl 15 crystallizes in the orthorhombic space group Pmma (no. 51) with lattice constants a = 1780.1(2), b = 1341.4(1), and c = 925.5(1) pm, Z = 4, and R1 = 0.039 for all 2727 observed reflections. [(Nb 6 Cl 12 i )Cl 6/2 a-a ] - anions in the structure are linked via two Cl a-a bridges to form one set of linear and one set of kinked chains along the crystallographic c and a directions. Four remaining Cl a-a bridges interconnect both sets of chains to a three-dimensional network. The potassium occupancy on a 4k site was refined to a value of 0.384(3) consistent with the formula K 0.77 Nb 6 Cl 15- . Ternäre Niobchloride des Formeltyps ANb 6 Cl 15 wurden bereits verschiedentlich beschrieben. Verbindungen mit A = Li [1] und Na [2] kristallisieren kubisch (Ia3̅d) mit identischen Schweratomstrukturen. Die Alkalimetall-Ionen Li (KZ = 4) und Na (KZ = 6 ) besetzen in den Strukturen ANb 6 Cl 15 aber unterschiedliche Splitlagen und sind dynamisch fehlgeordnet. Die Vertreter mit A = In und TI [3] kristallisieren orthorhombisch (Pmma). Ihre Kationen befinden sich in zweifach überdachten, würfelförmigen Cl-Umgebungen (KZ = 10). Die Kenntnis des Formeltyps ANb 6 Cl 15 mit schweren Alkalimetallen ist noch unvollständig. Einkristallstrukturuntersuchungen für A = Rb, Cs ergaben Kationenfehlordnungen [4, 5]. Für die Verbindung KNb 6 Cl 15 wurde eine Einkristallstrukturbestimmung durchgeführt (Tab. 1). Die Verbindung kristallisiert orthorhombisch in der Raumgruppe Pmma (Nr. 51) mit den Gitterkonstanten a = 1780,1(2), b = 1341,4(1) und c = 925,5(1) pm mit Z = 4 und ist isotyp zu den Inund TI-Verbindungen. Die Besetzung der K-Position (4k-Lage, mx-Punktsymmetrie) wurde zu 0,384(3) verfeinert, was der Zusammensetzung K 0.77 Nb 6 Cl 15 entspricht (Tab. 2) # . Die Nb-Nb-Abstände in KNb 6 Cl 15 liegen zwischen 291,47(6) und 296,45(7) pm, die Bindungslängen Nb-Cl I betragen 243,3(1) - 247,18(9) und die Nb-Cl a -Abstände 258,7(2) - 271,40(9) pm.

New intermetallic cadmium compounds RE 2 Rh 2 Cd (RE= La, Ce, Pr, Nd, Sm) were synthesized from the elements in sealed tantalum tubes in a high-frequency furnace. They were characterized through X-ray powder data: Mo 2 FeB 2 type, space group P4/mbm, Z = 2. Single crystal data of the cerium compound (a = 762.8(1), c = 377.8(1) pm, wR2 = 0.0662, 199 F 2 values, and 13 variable parameters) revealed small defects on the rhodium position leading to the composition Ce 2 Rh 186(3) Cd for the investigated crystal. According to the course of the cell volumes Ce 2 Rh 2 Cd may be classified as a mixedvalent compound. The Ce 2 Rh 2 Cd structure is an intergrowth of slightly distorted AlB 2 and CsCl related slabs of compositions CeRh 2 and CeCd. Within the CeRh 2 slab short Ce-Rh contacts (284-300 pm) are indicative of strong Ce-Rh bonding. The Rh-Rh distance within the AlB 2 related slab is 289 pm.