Volume 50, Issue 5

Single crystals of AgCdVO 4 have been prepared in closed silver tubes using V 2 O 5 as a flux. The light-orange crystals show orthorhombic symmetry, space group D 16 2h -Pnma, a = 9.786(2), b = 6.994(1), c = 5.439(1) Å, Z = 4. The hitherto unknown AgCdVO 4 is related to the Olivine structure but isotypic to Ag 2 CrO 4 and NaCd 4 (VO 4 ) 3 respectively. The differences in crystal chemistry between the Olivine type, NaCd 4 (VO 4 ) 3 and AgCdVO 4 are discussed.

Single crystals of the hitherto unknown compound CuSbMo 2 O 8 were prepared by recrystallization from melts in closed copper tubes and investigated by X-ray diffractometer technique. CuSbMo 2 O 8 crystallizes in a new structure type with monoclinic symmetry, space group C 6 2h - I12/a1, a = 5.554(2), b = 4.916(1), c = 21.519(4) Å, β = 93.42(3)°, Z = 4. The crystal structure shows Sb III in a one-sided coordination by four oxygen. Molybdenum shows the rare octahedral coordination by oxygen. MoO 6 and CuO 6 octahedra form triple layers stacked and connected by Sb ions along [001].

[Cs 4 (dibenzo-18-crown-6) 3 ](S 6 ) 2 ·2CH 3 CN has been prepared from dibenzo-18-crown-6, Cs 2 CO 3 and suifur in acetonitrile saturated with H 2 S. The title compound crystallizes in space group P 1̄ (lattice dimensions: a = 10,507(7) Å, b = 11,504(6) Å, c = 17,792(9) Å, α = 97,86(4)°, β = 105,86(4)°, γ = 101,48(5)°) with one formula unit. The crystallographic units are built of stacks of three crown ether molecules and two hexasulfide chains with the cations located between them. The conformation of the hexasulfide chains is all-cis.

The mixed valence compound Ga 1.93 V 0.97 S 4 has been prepared and characterized by X-ray powder methods. The compound crystallizes in an α-FeGa 2 S 4 structure. The lattice parameters of the hexagonal cell are a = 363.6 and c = 1207.1 pm. The structure has been refined by Rietveld methods.

Di-n-butyltin dimethylphosphinate has been synthesized by the reaction of (n-Bu) 2 Sn(OCOCH 3 ) 2 with HO 2 PMe 2 in benzene. The ractions of (n-Bu) 2 Sn(OCOCH 3 ) 2 with MePhPOCl and Ph 2 POCl in toluene have been used to prepare (n-Bu) 2 Sn(O 2 PMePh) 2 and (n-Bu) 2 Sn(O 2 PPh 2 ) 2 respectively. On the basis of vibrational spectra and physical properties it is conclu ded that the title compounds are polymerized and the ligands function as O-P-O bridges between the tin atoms. The n-butyl groups are in trans position in the resulting octahedral environment around tin. Loss of n-butyl radicals and of the diorganophosphinate group from tin represent the main fragmentation processes in the El mass spectra of (n-Bu) 2 Sn(O 2 PRR′) 2 (RR′=Me 2 , MePh, Ph 2 ). The mass spectra show Sn(O 2 PRR′) + as the base peak.

Cyclopentadienyl nickel complexes [(C 5 H 2 tBu 3 -1,2,4)Ni(M-CO)] 2 (1) and [(C 5 HiPr 4 )Ni(μ-CO)] 2 (2) have been synthesized from nickel tetracarbonyl and the corresponding lithium cyclopentadienide, and [(C 5 iPr 5 )Ni(μ-CO)] 2 (3) has been obtained in high yield from nickel tetracarbonyl and the free pentaisopropylcyclopentadienyl radical. The crystal structure of 1 shows a complex on a crystallographic mirror plane with a bent Ni-C-Ni-C core whereas the crystal structure of 2 exhibits two independent planar molecules possessing crystallographic inversion symmetry.

Pale bluish-green single crystals of the new compound CuTb 2 [B 8 O 16 ] have been obtained by a B 2 O 3 flux technique. They crystallize in an unknown structure type. X-ray investigations on single crystals led to the space group C 5 2h -P2 1 /c (Nr. 14) with lattice parameters a = 1024.6(1); b = 834.93(6); c = 622.87(6) pm , β = 90.45(2)°; Z = 2. The structure contains 1 ∞ [B 8 O 16 ] 8- chains isolated from each other, which include tri- and tetracoordinated boron. The chains consist of alternating twelve- and eight-membered rings of boron and oxygen connected by BO 4 units. Tb 3+ is octacoordinated and Cu 2+ is hexacoordinated in elongated octahedra by oxygen. The relation to the crystal structures of Tb[B 3 O 6 ] and CuTb[B 5 O 10 ] is pointed out.

Single crystals of the compounds CuM[B 5 O 10 ] (M = Tm 3+ (I), Lu 3+ (II) have been obtained by a B 2 O 3 flux technique. Their structures are isotypic with CuTb[B 5 O 10 ]. X-ray investigations on single crystals led to the space group C 21 2v -Iba2 (Nr. 45); I: a = 622,0(2) pm; b = 844,7(1) pm; c = 1266,3(4) pm; Z = 4 and II: a = 618.4(1) pm; b = 845,9(2) pm; c = 1260,9(4) pm; Z = 4. The structure contains 1 ∞ [B 5 O 10 ] 5- chains that include twelve membered rings of boron and oxygen. Each ring consists of two tetrahedral BO 4 and two planar B 2 O 5 groups and is connected with neighboring rings via the BO 4 units. M 3+ (M = Tm 3+ , Lu3 + ) is eight-coordinated, while Cu 2+ is hexa-coordinated by oxygen.

By reduction of [B 6 H 3 (NO)B 6 H 5 ] 3- with Fe 2+ in aqueous alkaline solution [B 6 H 3 (NH 2 )B 6 H 3 ] 3- is formed. It reacts as a Brönsted base and becomes protonated in neutral medium to give the mono anion [B 6 H 6 (NH 2 )B 6 H 6 ] - . The crystal structure of the salt [As(C 6 H 3 ) 4 ][B 6 H 6 (NH 2 )B 6 H 6 ] has been determined by single crystal X-ray diffraction analysis; triclinic space group P1̄ with a = 8.284(2), b = 12.619(2), c = 15.5 4 3 (3 )Å and α = 69.193(13)°; β = 88.59(2)°, γ = 87.24(2)°. The 11 B NMR spectrum is consistent with mono hetero substituted octahedral B 6 cages with local C 4v symmetry. The IR and Raman spectra exhibit characteristic N-H , B-H and B 6 vibrations.

By reduction of [B 6 H 5 (NO 2 )] 2- with aluminium powder in aqueous alkaline solution the orange μ-dinitrogen-bis(pentahydro-closo-hexaborate)(2-), [B 6 H 5 (NN)B 6 H 5 ] 2- , is formed, which can be precipitated with tetraphenylarsonium ions. The crystal structure of [As(C 6 H 5 ) 4 ] 2 [B 6 H 5 (NN)B 6 H 5 ] has been determined by single crystal X-ray diffraction analy­sis; tetragonal, space group P4/n with a = 12.6610(12), c = 14.6790(11) Å. The B 6 cages are slightly compressed (2%) in the direction of the connecting linear N 2 bridge with bond lengths N-N of 1.129 and B-N of 1.421 Å. The 11 B NMR spectrum exhibits signals at -27.0 (ipso-B), +1.26 (equatorial-B), +3.54 ppm (antipodal-B atoms). The NN stretching vibration is observed in the Raman spectra as a very strong line at 2065 cm -1 .

Lithium tetrahydrogen cyclopentaphosphide. LiH 4 P 5 (I). has been obtained by metalation of P 2 H 4 at -78 °C with either n-BuLi or LiPH 2 in polar solvents. Upon suitable performance of the reaction, compound I can be isolated at low temperature as a lemon-yellow solvent adduct. The structure as the monolithium salt of (PH) 5 was confirmed by a complete analysis of the 31 P{ 1 H}-NMR spectrum. On warming above -35 °C, disproportionation occurs yield­ing Li 2 HP 7 . P 2 H 4 . and PH 3 . The reaction with n-BuLi produces the open-chain phosphides LiH 4 P 3 . LiH 3 P 2 , and LiPH 2 . The NMR parameters of LiH 3 P 2 and LiH 4 P 3 are reported. Reac­tion of 1 with P 2 H 4 gives rise to the bicyclic and polycyclic phosphides LiH 4 P 7 , LiH 5 P 8 and Li 2 H 2 P 14 , respectively.

The adduct formation between 2-trimethylstannyl-pyridine (1) and triethylborane, leading to 2a, and 9-borabicyclo[3.3.1]nonane, leading to 2b, was studied by 1 H, 11 B, 13 C, 15 N and 119 Sn NMR in solution. Changes in the magnitude of the coupling constants J( 119 Sn, 13 C), with respect to the data for I, were analysed. The absolute signs have been determined [all coupling constants n J( 119 SnZ 3 C) to methyl and pyridine carbon atoms in 1 to 3 possess a negative sign and the same is true for n J( 119 Sn, 1 H) of the pyridine hydrogen atoms] by various two-dimensional NMR experiments, and attributed to the influence of the lone pair of electrons at the nitrogen atom in 1. The NMR spectroscopic results for the 1,4-dihydro- 4a,1,4-azastannabora-naphthalene derivative 3, in which structural fragments are present analogous to those in the borane adducts 2, correspond to those for 1 and 2a,b. The molecu­lar structure of 3 has been determined by X-ray analysis [orthorhombic; P2 1 2 1 2 1 , a = 713.9(2), b - 1566.0(2), c = 1578.4(2) pm]. Solid-state 13 C and 119 Sn CP/MAS NMR spectra prove that the molecular structures of 3 in the solid state and in solution are very similar.

The complex [(TMEDA)Ni(μ-H,μ-CO)Ni (TMEDA)]X 1a (TMEDA: N,N,N',N'-Tetramethylethylenediamine, X: Monoanions of cis-cyclohex-4-ene- or cyclohexane-dicarboxylic acid) could be isolated as the product of a stepwise reaction in THF solution of Ni(COD) 2 , TMEDA and cis-cyclohex-4-ene-dicarboxylic-anhydride in the presence of a small amount of water. Similar results are obtained with cyclohexane-dicarboxylic-anhydride. NMR- and IR-spectroscopic measurements and the single crystal X-Ray diffraction analysis of 1a have established the structure: Both a hydride- and a carbonyl bridge are linking two (TMEDA)Ni fragments in the cationic part. The Ni(I) centers are connected by a Ni-Ni-bond . The compounds are the first (TMEDA)Ni(I) complexes and the first binuclear hydrido-carbonylcomplexes which are stable without further bridging and π-acceptor ligands. They contain hydrido and protic hydrogen in the same compound.

The reaction of the series of methyl/phenylchlorosilanes Me 2 PhSiCl, MePh 2 SiCl and Ph 3 SiCl with CHBr 3 /n-BuLi to give the corresponding bromo-di(silyl)methanes has been investigated. The selectivity of the reaction proved to be strongly influenced by the number of phenyl groups bound to silicon. As already established for Me 3 SiCl, Si-C coupling readily occurs with Me 2 PhSiCl to give (Me 2 PhSi) 2 CHBr (1) in good yields, whereas MePh 2 SiCl affords (MePh 2 Si) 2 CHBr (2) in lower yields. The molecular structures of 2 and the by-product (MePh 2 Si) 2 CBr 2 have been determ ined by single crystal X-ray diffraction. In the case of the fully arylated species, Ph 3 SiCl, only the monosilylated compound (Ph-Si)CH 2 Br (3) is generated. (HMe 2 Si) 2 CHBr (5) can be obtained starting from 1 by treatment with triflic acid to give (CF 3 SO 3 Me 2 Si) 2 CHBr (4), followed by reduction of 4 with LiAlH 4 in diethyl ether. In situ metalation of 5 with n-BuLi affords (HMe 2 ) 2 CHLi, which reacts instantaneously with a second equivalent of 5 to give the halogen-free dimer [(HMe 2 Si) 2 CH]SiMe 2 CH 2 SiMe 2 H (6).

Me 3 CSiHal 3 react with LiOCMe 3 to give Me 3 CO(Me 3 C)SiHal 2 (HaI = F (1), Cl (3)). The aminofluorosilane, Me 3 CO(Me 3 C)SiFNH 2 (2), is formed in the reaction of 1 with LiNH 2 . The diaminosilane Me 3 CO(Me 3 C)Si(NH 2 ) 2 (4) is obtained from the reaction of 2 with ammonia. 4 reacts with LiC 4 H 9 to give the lithium derivative Me 3 CO(Me 3 C)Si(NHLi)NH 2 (5). In a molar ratio 1:1 the reaction of 5 and 1 leads to the formation of the 1-amino-3-fluoro-disilazane Me 3 CO(Me 3 C)SiF- NH - SiNH 2 (CMe 3 )OCMe 3 (6) and in a molar ratio 2:1 to the four-membered silicon nitrogen ring [Me 3 CO(M e 3 C)Si-NH] 2 (7). The crystal structure of 7 was determined.

[SnCl 4 (Ph 2 PCH 2 -CH 2 PPh 2 )] CH 2 Cl 2 has been characterized by a crystal structure determ ination. Space group P2 1 /c, Z = 4, 5565 observed unique reflections with I > 2 σ(I), R = 0.043. Lattice dimensions at -70 °C: a = 1141.4(6), b = 2178.3(11), c = 1399.1(7) pm, β = 108.96(3)°. The complex forms monomeric molecules with the 1.2-bis(diphenylphosphino)ethane as chelating ligand. Bond lengths (average): Sn - P 266.7 pm, Sn - Cl 241.8 pm.