Synthesis and Spectroscopic and Magnetic Properties of a Unique Diamagnetic Binuclear µ-Vanadium(IV) Complex. Crystal Structure of [(tpa)V0^-0)V0(tpa)](CI04)2 (tpa = Tris(2-pyridylmethyl)amine)

The title compound, [Ba4{/z3-OTi(C3H70)4}4(C3H7-OH)3], is a BaTiO3 molecular precursor. The structure is based on a Ban tetrahedral cluster with all faces capped by OTi(Oipr)4 groups. Two of the faces are symmetrically capped (three #2-0 atoms) and two are unsymmetrically capped (two /z2-O atoms and one ~3-O atom). CommentThe thermal transformation of organometallic compounds is of interest in the sol-gel production of ceramics. Two areas of current interest are the formation of ferroelectric ceramics, e.g. BaTiO3, and hightemperature superconductors, e.g. YBa2Cu3OT. Sol-gel

Reaction of 1,3-dicyanotetrafluorobenzene with 2 equiv of (trimethylsilyl)iminophosphoranes gave the disubstituted derivatives 4,6-(CN)(2)C(6)F(2)-1,3-AB: 1, A = B = (N=PPh(3)); 2, A = B = (N=PPh(2)Me); and 3, A = (N=PPh(3)), B = (N=PPh(2)Me). Monosubstituted compounds of the type 2,4-(CN)(2)C(6)F(3)-1-A; notably 4, A = (N=PPh(3)), and 5, A = (N=PPh(2)Me), were readily obtained by reaction of 1 molar equiv of the silylated iminophosphorane with the cyanofluoro aromatic. Substitution of the fluorine para to the CN group(s) occurs in all cases. Reactions of 1,2- and 1,4-dicyanotetrafluorobenzene with (trimethylsilyl)iminophosphoranes gave only monosubstituted derivatives 3,4-(CN)(2)C(6)F(3)-1-A (6, A = (N=PPh(3)), and 7, A = (N=PPh(2)Me)) and 2,5-(CN)(2)C(6)F(3)-1-A (8, A = (N=PPh(3)), and 9, A = (N=PPh(2)Me)), respectively, as the result of electronic deactivation of the second substitutional point. 1, 4,6-(CN)(2)C(6)F(2)-1,3-(N=PPh(3)), 2, 4,6-(CN)(2)C(6)F(2)-1,3-(N=PPh(2)Me)(2), and 3, 4,6-(CN)(2)C(6)F(2)-1-(N=PPh(3))-3-(N=PPh(2)Me) have been structurally characterized. For 1 (at 21 degrees C), monoclinic, C2/(c) (No. 15), a = 15.289(2) Å, b = 10.196(1) Å, c = 23.491(6) Å, beta = 91.63(2) degrees, V = 3660(2) Å(3), and Z = 4. The P=N bond length is 1.579(2) Å and the P(V)-N-C(phenyl) angle is 134.0(2) degrees. For 2, (at 21 degrees C) monoclinic, C2/(c) (No. 15), a = 18.694(2) Å, b = 8.576(1) Å, c = 40.084(4) Å, beta = 94.00(1) degrees, V = 6411(2) Å(3), and Z = 8. The P(1)=N(1) bond length is 1.570(4) Å, the P(2)=N(2) bond length is 1.589(3) Å, the P(1)-N(1)-C(14) angle is 131.6(3) degrees, and the P(2)-N(2)-C(16) angle is 131.3(3) degrees. For 3, (at -80 degrees C) monoclinic, P2(1)/c (No. 14), a = 9.210(1) Å, b = 18.113(2) Å, c = 20.015(2) Å, beta = 100.07(1) degrees, V = 3287(2) Å(3), and Z = 4. The P(1)=N(1) bond length (PPh(3) group) is 1.567(4) Å, the P(2)=N(2) bond length (PPh(2)Me group) is 1.581(5) Å, the P(1)-N(1)-C(1) angle is 140.4(4) degrees, and the P(2)-N(2)-C(3) angle is 129.4(4) degrees. These new multifunctional chelating ligands readily react with [Rh(cod)Cl](2) and AgClO(4) to give cationic Rh(I) complexes in which the imine and/or the nitrile groups are coordinated to the Rh center.

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