小澤 芳樹

A novel halogen-bridged one-dimensional Ni^III–X–Ni^III compound, {[Ni^III(en)₂Cl]Cl₂}_∞ (en = C₂H₈N₂) has been synthesized by electrochemical oxidation. Single crystal X-ray crystallography revealed that a bridging halogen ion is located on the midpoint between two Ni(III) atoms with Ni–Cl 2.438 (1) Å. This is the first example for electrocrystallization of halogen-bridged 1-D metal complexes.

Reaction of the triple cubane-type cluster [(Cp^*Rh)₄Mo₄O₁₆] with MeSH gave two tetranuclear complexes of [{Cp^*Rh(μ-SMe)₃MoO}₂(μ-O)₂] and [{Cp^*Rh(μ-SMe)₃MoO}₂(μ-O)(μ-S)] which were characterized by X-ray structural analysis. The stereodynamics of the two complexes was studied by variable-temperature ¹H and ¹⁷O NMR as well as ¹³C NMR spectroscopy.

Reaction of the triple cubane-type cluster [((CPRh)-Rh-*)(4)Mo4O16] with MeSH gave two tetranuclear complexes of [{Cp*Rh(mu-SMe)(3)MoO}2(mu-O)(2)] and [{Cp*Rh-(mu-SMe)(3)MoO}(2)(mu-O)(mu-S)] which were characterized by X-ray structural analysis. The stereodynamics of the two complexes was studied by variable-temperature H-1 and O-17 NMR as well as C-13 NMR spectroscopy.

A mixed metal tetranuclear complex with two Mo^VI(μ-SMe)₃Rh^III groups, [{Cp^*Rh(μ-SMe)₃Mo(O)₂}₂(μ-O)] has been obtained from the reaction of the triple-cubane type oxide cluster [(Cp^*Rh)₄Mo₄O₁₆] with MeSH. The complex has been characterized by X-ray analysis and variable-temperature ¹H NMR spectroscopy. The latter has revealed that the complex exists as a mixture of isomers which show interconversion due to the inversion at the pyramidal sulfur center.

A heterotrimetallic sulfide cluster with an organometallic group, [Cp^*Rh{P(OEt)₃}(μ-S)₂W(μ-S)₂CuCl] (Cp^* = η⁵-C₅Me₅), was prepared stepwise by using mononuclear units of organorhodium(III), thiotungstate(VI), and chlorocopper(I). X-ray crystal structure analysis revealed that the cluster possesses a linear sequence of middle (Rh), early (W), and late (Cu) transition metal atoms with octahedral, tetrahedral, and trigonal planar coordination geometries, respectively.

Reaction of [(η3-C4H7)2Rh(CH3CN)2]PF6(η3-C4H7 = β-methallyl) with [n-Bu4N](VO3) gives a new η3-allyl cluster [n-Bu4N]2[{(η3-C4H7)2Rh}2 (V4O12)] (I) which is readily converted into a diene cluster, [n-Bu4N]2 [{(η4-C8H14)Rh}2(V4O12)] (II) (C8H14=2,5-dimethyl-1,5-hexadiene) by reacting with CO or P(OEt)3 I and II have been characterized crystallographically. © 1991 Plenum Publishing Corporation.

Reaction of [(η 3 -C 4 H 7 ) 2 Rh(CH 3 CN) 2 ]PF 6 (η 3 -C 4 H 7 = β-methallyl) with [n-Bu 4 N](VO 3 ) gives a new η 3 -allyl cluster [n-Bu 4 N] 2 [{(η 3 -C 4 H 7 ) 2 Rh} 2 (V 4 O 12 )] (I) which is readily converted into a diene cluster, [n-Bu 4 N] 2 [{(η 4 -C 8 H 14 )Rh} 2 (V 4 O 12 )] (II) (C 8 H 14 =2,5-dimethyl-1,5-hexadiene) by reacting with CO or P(OEt) 3 ;I and II have been characterized crystallographically. © 1991 Plenum Publishing Corporation.

Neutral organometallic oxide clusters [MCp*)4V6O19] (M = Rh (1), Ir (2); Cp* = eta-5-C5Me5) were synthesized by the reaction of [MCp*Cl2]2 with sodium metavanadate in high yield (1, 90%; 2, 96%). The structure has a quadruple-cubane-type framework, including the first vanadate hexamer with a V6O19 core [Hayashi, Y.; Ozawa, Y.; Isobe, K. Chem. Lett. 1989, 425]. The water suppression O-17 NMR spectrum of [(RhCp*)4V6O19] enriched with O-17 showed that a site-selective oxygen exchange with free water occurs at the bridging oxygen atoms in the cluster without any change in its skeleton in the range of pH 6-8. Cluster 1 liberates sequentially [RhCp*(H2O)3]2+ groups in acidic water of pH < 4. Treatment of this acidic aqueous solution with [IrCp*(H2O)3]2+ gave a mixture of clusters, [(RhCp*)4-n(IrCp*)nV6O19] (0 less-than-or-equal-to n less-than-or-equal-to 4) (n = 1 (3), n = 2 (4), n = 3 (5)). These clusters were separated with a silica gel column and characterized by elemental analysis and IR and H-1, C-13, and V-51 NMR spectroscopies. 3 crystallizes in the orthorhombic space group Pmmm with a = 15.169 (3) angstrom, b = 18.632 (4) angstrom, c = 11.681 (1) angstrom, Z = 2, R = 0.046, and R(w) = 0.0637 for 3432 reflections, that is, isomorphous with 1. Although the location of the RhCp* and IrCp* groups in 3 was not specified by X-ray analysis due to their disorder, the chemical shifts of V-51 NMR spectra of 3 and the other mixed organometallic clusters clearly indicated that there is a magnetic nonequivalence between the vanadium atoms adjacent to the RhCp* group and those adjacent to the IrCp* group.

(NH4)3[H6RhMo6O24].6H2O, M(r) = 1230.79, monoclinic, P2(1)/c, a = 11.435 (3), b = 11.017 (2), c = 11.789 (2) angstrom, beta = 100.02 (2)degrees, V = 1462.6 (6) angstrom3, Z = 2, D(m) = 2.83, D(x) = 2.79 Mg m-3, lambda(Mo K-alpha) = 0.71069 angstrom, mu = 3.08 mm-1, F(000) = 1176, T = 296 K, final R = 0.042 for 2248 observed reflections with \F0\ > 3.0-sigma(\F0\). The [H6RhMo6O24]3- polyanion, which has approximate D3d symmetry, is isostructural to [H6Cr(III)Mo6O24]3-. The RhO6 octahedron located on an inversion center is trigonally distorted with the Rh-O distances in the range 2.019 (5)-2.030 (5) angstrom. The Mo-O distances are in the range 1.701 (7)-2.298 (5) angstrom.

Novel transition metal sulfide cluster [(η⁵–C₅Me₅)MWO(μ–S₂)(μ–S)₂]₂ (M = Rh, Ir) was synthesized and the crystal structure of iridium complex was analyzed. The cluster consists of two fused double incomplete-cubane frameworks made of tungsten(VI) and iridium(III) atoms. There are no metal–metal direct interactions within the cluster core in spite of short W–Ir contact of 2.816(1) Å.

Reaction of [Cp^*RhCl₂]₂ (Cp^* = η⁵-C₅Me₅) with NaSMe in H₂O–MeOH (1:1 by volume) gave [Cp^*Rh(μ-SMe)₃RhCp^*]Cl·2H₂O which was converted to [Cp^*Rh(μ-SMe)₃RhCp^*]₂[W₃S₉] by treatment with WS₄^2−. In the presence of MoO₃ the reaction led to formation of [Cp^*RhCl(μ-SMe)₂RhCp^*Cl]. X-Ray structure analyses revealed that [Cp^*Rh(μ-SMe)₃RhCp^*]₂[W₃S₉] has three μ₂-bridged SMe ligands and that [Cp^*RhCl(μ-SMe)₂RhCp^*Cl] has a syn-planar conformation with two μ₂-bridged SMe ligands.

The organometallic oxide clusters [(MCp^*)₄V₆O₁₉] (M = Rh, Ir; Cp^* = C₅Me₅) were prepared and characterized by elemental analyses, SIMS as well as IR and NMR (¹H, ¹³C, ¹⁷O, ⁵¹V) spectroscopy. Single crystal X-ray analysis showed that [(RhCp^*)₄V₆O₁₉]·4CH₃CN·H₂O contains the vanadate hexamer core (V₆O₁₉). The rhodium cluster displays site selective oxygen exchange with free water at the bridging oxygen atoms.

Photochemical reaction of 2,3-dichloro-1,4-naphthoquinone with 1,1-diphenylcyclopropane gave a spirofuran adduct as the sole photoproduct.

A novel dodecamolybdodiarsenate(III) salt [(CH₃)₄N]₄Na₂[As₂Mo₁₂O₄₂]·6H₂O is synthesized and its crystal structure is determined. The trivalent As heteroatoms with an unshared electron pair are bonded to three O atoms with the distances of 1.79 Å to form AsO₃ trigonal pyramids. The polyanion molecule has no symmetry elements, consisting of twelve distorted MoO₆ octahedra.

A novel heteropolytungstate salt [(CH₃)₄N]₆[H₃BiW₁₈O₆₀] is prepared and its crystal structure is determined : monoclinic, P2₁/c, a=13.986(7) Å, b=15,134(2), c=23.250(8), β=115.32(3)°, Z=2. The anion has the same framework as that found in 18-tungstoarsenate(III)(AsW₁₈O₆₀). The Bi atom is coordinated by three O atoms and is on the apex of BiO₃ trigonal pyramid.