V. E. Shklover

An Unusual sandwich-type nickel oxide-siloxanolate complex {[PhSiO]}6 (μ4-O)2 (μ3-O)4[Ni8(μ3-0)2](μ3-O)4(μ4-O)2 [PhSiO]6}·14n-BuOH·10H2O·2Me2CO. Synthesis and crystal structure

Abstract An X-ray crystal study of the nickel oxide-siloxanolate complex {[PhSiO] 6 (μ 4 -O) 2 (μ 3 -O) 4 [Ni 8 (μ 3 O) 2 ] (μ 3 -O) 4 (μ 4 -O) 2 [PhSiO] 6 }·14n-BuOH·10H 2 O·2MeCO (I or Ia without noncoordinating solvate molecules) having a cage structure has been carried out. The complex studied was prepared by the interaction of NiCl 2 with the product of the reaction of phenylsilsesquioxane (PhSiO 1.5 ) n with NaOH. The polynuclear cage-like centrosymmetric molecule Ia has a sandwich-type structure. The inner two-dimensional nickel oxide fragment Ni 8 o 2 (μ-O) 12 2 = Ni 8 O 8 is structurally identical to a fragment of the NiO crystal layer which is one Ni atom thick and parallel to the (111) plane. All Ni atoms have oxygen atoms in an octahedral coordination (oxide, silanolate, molecules of water, butanol and acetone). The O atoms of the nickel oxide layer have both trigonal pyramidal (μ 3 -O) and distorted tetrahedral (μ 4 -O) coordination. The nickel oxide layer is bonded by NiOSi bridges through silanolate O atoms with two outer 12-membered hexasiloxane (SiO) 6 cycles (sandwich “caps”) with an almost ideal crown conformation. Some of the butanol and H 2 O crystallosolvate molecules do not coordinate the Ni atoms being included in the cavities between Ia molecules. The NiO bond lenghts are 2.006–2.159 A, while the average SiO(Si) and SiO(Ni) bond lengths are 1.637 and 1.618 A, respectively.

Conformations of eight-membered cyclosiloxanes

Abstract Using the Cremer—Pople approach the classification and quantitative description of the conformations of eight-membered rings has been accomplished. The conformations of eight-membered cyclosiloxanes are considered and classified on the basis of available X-ray structural data.

Antiferromagnetic complexes with metal-metal bonds: IX. Synthesis and molecular structures of methylcyclopentadienylchromium(III) sulfide diamagnetic tetramer and the antiferromagnetic copper(II) bromide adduct of the tetranuclear cluster (MeC5H4)4Cr4(μ3-O)(μ3-S)3

Abstract Reaction of (MeC5H4)2Cr with HSCMe3 gave (MeC5H4)2Cr2S(SCMe3)2 (I) in the form of violet antiferromagnetic crystals ( − 2J = 478 cm−1). Pyrolysis of I in xylene and its reaction with a CuBr2 solution in THF/Et3N (1/1) leads to readily-soluble black diamagnetic crystals of (MeC5H4)4Cr4S4(II). An oxygen-containing antiferromagnetic analog of complex II, (MeC5H4)4Cr4O4(III) was isolated on oxidation of (MeC5H4)2Cr with traces of oxygen in the presence of Ar. The reaction of I with CuBr2 in the absence of Et3N yielded black-green needle-like crystals of the antiferromagnetic adduct (MeC5H4)4Cr4S3O · CuBr2(IV) (μeff at room temperature is 3.91 BM). The structures of II and IV were established by X-ray crystallography. The molecule of II contains a metallotetrahedral Cr4 skeleton (CrCr 2.822(2) A) with faces centered at the μ3-bridged S atoms (CrS 2.248(2) A). Each Cr atom is bonded to a η5-MeC5H4 (CrCaver. 2.241(9) A). In IV the tetrahedral Cr4 skeleton is distorted owing to the μ3-O bridging ligand (CrCr 2.70(1)–2.78(1) A, CrSaver. 2.25(2) A, CrO 2.07(2)–2.12(2) A) and to CuBr2 coordination to a sulfur atom (CuBr 2.23(2) A, BrCuBr 163.9(8)°, Cu···S 320 A).

Cationic dithiolene metal complexes with 5,6-dihydro-1,4-dithiin-2,3-dithiol: Highly conducting metal complex analogues of BEDT-TTF salts

Abstract A new class of highly conducting compounds (cationic dithiolene metal complexes of Ni and Au with 5,6-dihydro-1,4-dithiin-2,3-dithiol (DDDT), which are metal complex analogues of BEDT-TTF salts) has been obtained. The crystal structure of one of the representatives of this class, [Ni(DDDT) 2 ] 3 (BF 4 ) 2 , has been determined. The crystal contains stacks of [Ni(DDDT) 2 ] cations with shortened intra- and interstack S·S contacts. The conductivity of these complexes at room temperature is 1 – 50 ohm −1 cm −1 .

Synthesis and molecular structure of lanthanum tris[cyclopentadienylmolybdenotricarbonylate] tetrahydrofuranate, (THF)5La[CpMo(CO)3]3•THF

Abstract The interaction of activated La powder with [CpMo(CO) 3 ] 2 or Hg[CpMo(CO) 3 ] 2 in THF resulted in the formation of crystalline (THF) 5 La[CpMo(CO) 3 ] 3 · THF (I), which oxidized readily on exposure to air with cleavage of [CpMo(CO) 3 ) 2 . Complex I was characterized by X-ray structural analysis. The La atom is bound to three equivalent CpMo(CO) 3 fragments via almost linear carbonyl bridges, MoCOLa (MoCO 177.9(7)°). The coordination of La with the terminal CO group (LaO av 2.444(5) A) leads to elongation of the CO bond from an average value of 1.16(1) to 1.21(1) A, and to shortening of the MoC bond from an average value of 1.943(9) to 1.874(9) A, compared with the unbridged CO. The coordination of La is complemented to CN = 8 at the expense of binding of five THF molecules (LaO(THF) av = 2.580(6) A; the sixth THF molecule is crystallizable).

New class of metal BIS-dithiolene electroconducting solids: Cation complexes of metals with dddt

Abstract Electroconducting solids have been synthesized based on the M(dddt) 2 (M = Ni, Pt, Au) cation complexes, which represent a new class of bis-dithiolene chelates. Their salts are analogs to the ET salts. Crystal structures and conducting properties of [M(dddt) 2 ] π+ salts have been studied and compared with the ET salts.

Crystal and molecular structures of (O-Ge)-chelate 1-(dimethylchlorogermylmethyl)pyrrolidone-2 and 1-(dimethylchlorogermylmethyl)piperidone-2, and of (N-Ge)-chelate O-(dimethylchlorogermylmethyl)-δ-valerolactim and 2-(chlorodimethylgermylmethylthio)-pyrrolidine-1. Structural correlations between derivatives of four- and five-coordinated germanium

Abstract An X-ray study of (O-Ge)-chelate 1-(dimethylchlorogermylmethyl)pyrrolidone-2 ( 1 ), 1-(dimethylchlorogermylmethyl)piperidine-2 ( 2 ), (N-Ge)-chelate O -(dimethylchlorogermylmethyl)-δ-valerolactim ( 3 ), and 2-(chlorodimethylgermylmethylthio)pyrrolidine-1 ( 4 ) has been carried out ( R = 0.033, 0.062, 0.097 and 0.048 for 1241, 2351, 1242 and 1838 reflections, respectively). The Ge atom has a distorted trigonal-bipyramidal [3 + 2] coordination with the axial Cl and O atoms in 1 and 2 or Cl and N atoms in 3 and 4 . The axial distances are Ge-Cl 2.324(2), 2.354(2), 2.458(8) and 2.566(2) A, Ge ← O 2.311(4) and 2.194(2), Ge ← N 2.148(18) and 2.064(5) A in 1 – 4 respectively. Correlation between structural parameters of the compounds of five- and four-coordinated germanium have been considered.

Synthesis and molecular structure of the niobocene sulphide dimer

Abstract The reaction of Cp 2 NbBH 4 in benzene in the presence of Et 3 N and PhSH results in a green, crystalline, diamagnetic complex, [Cp 2 NbSPh] n (I), which probably has a polymer structure. The reaction of Cp 2 NbBH 4 under the same conditions with t-BuSH or (CpCrSCMe 3 ) 2 S yields a red, crystalline, diamagnetic complex, [Cp 2 NbS] 2 (II), whose structure was established by X-ray analysis. In II, the Nb atom belongs to the niobocene fragment, whose inclined rings (dihedral angle 47.25°) are in a staggered conformation (NbC Cp(av.) 2.452(7), CC Cp(av.) 1.40(1) A). Moreover, each Nb atom forms two equivalent short bonds, NbS (2.429(2) and 2.427(2) A), and the angles NbSNb (83.51(5)°) are coequal, as are the SNbS angles (96.49(6)°). The NbNb distance (3.2343(8) A) is evidently bond-forming. The molecule on the whole resembles C 2ν in symmetry.

Antiferromagnetic complexes with metalmetal bonds: XVIII. The influence of electronic factors on geometry of heterometallospirane clusters. Molecular structure and magnetic properties of Cp2Cr2(μ-SCMe3)(μ3-S)2M(μ3-S)2Fe2(CO)6 (M = Fe, Rh) and (MeC5H4)2Cr2(μ-SCMe3)(μ3-S)2Co(μ3-S)2Fe2(CO)6☆

Reaction of Cp2Cr2(SCMe3)2S (I) with Fe3S2(CO)9 gives the novel metallospirane cluster Cp2Cr2(μ-SCMe3)(μ3-S)2Fe(μ3-S)2Fe2(CO)6 (II). Analogous clusters with Co and Rh as central ions (III and IV respectively) have been obtained from the reaction of (MeC5H4)2Cr2(μ-SCMe3)(μ3-S)2Co(CO)2 or Cp2Cr2(μ-SCMe3)(μ3-S)2RhL2 (L = CO, L2 = COD) with Fe2(CO)6S2. The X-ray diffraction study of II (space group P1, a 9.691(4), b 12.294(3), c 14.515(5) A, α 66.25(2), β 74.89(3), γ 78.61(3)°, V 1519.8 A3, Z = 2) reveals Cr2Fe and Fe3 triangles in the Cr2FeFe2 metallospirane core at a dihedral angle of 106.8°, and the geometry of dichromium disulfide thiolate fragment remains unchanged as compared to I, III and IV (CrCr 2.689; 2.610(2); 2.598(2); 2.608(5) A in IIV, respectively). II has strong CrFe bonds (2.717(2) and 2.727(2) A, but the two bonds between the central and peripheral Fe atoms (3.018(2) and 3.032(2) A) are relatively weak. The peripheral FeFe bond (2.503(2) A) is still rather short. Formal replacement of the Fe atom in II by the Co atom in III (space group Pnam, a 14.549(2), b 14.480(2), c 14.146(2) A, V 2980.1 A3, Z = 4) results in the rupture of the FeFe bond (Fe…Fe 3.399(2) A) and formation of the two single CoFe bonds (2.554 (2) and 2.538(2) A). The dihedral angle between the planes of the metal triangles Cr2Co and CoFe2 in III is 90°. The geometry of the Rh(S)2Fe2(CO)6 moiety in the Rh-containing metall-spirane IV (space group P21/n, a 9.800(2), b 12.983(3), c 22.606(5) A, β 97.05(2)°, V 2854.3 A3, Z = 4) is not significantly different from that of the Co(S)2Fe2(CO)6 fragment in III (RhFe 2.650(4) A, Fe…Fe 3.344(4) A), the main difference involves the dihedral angle between the Cr2Rh and RhFe2 planes, which is 129.1° in IV. This difference being due to the tendency of the RhI atom to form the square planar complexes on one hand, and to decreasing the repulsion between the S atoms and the strengthening the RhCr bonds in the nonplanar ligand environment of the Rh atom on the other.

Direct evidence of the existence of organic derivatives of pentacoordinated silicon with the Si ← Cl coordinate bond. Molecular structure of chloro [1-{1,1-dimethyl-2-(4′methoxybenzoyl}hydrazonium) methyl] dimethylsilane

Abstract An X-ray study of chloro[1-{1,1-dimethyl-2-(4′methoxybenzoyl)hydrazonium} methyl]dimethylsilane (I) has been carried out ( R = 0.035 for 2800 reflections). The Si atom, which has a trigonal-bipyramidal [4 + 1] coordination with the O and Cl atoms in axial positions (Si–O 1.788(1) A, SiCl 2.624(1) A, is markedly displaced from the equatorial plane towards the oxygen atom (Δ Si 0.178 A), which confirms that there is a coordinate bond between the silicon atom and chloride ion.