NB2W4O194- AND P3O93- COMPLEXES OF (CYCLOOCTADIENE)IRIDIUM(I) - SYNTHESIS, STRUCTURE, AND STABILITY OF TETRA-N-BUTYLAMMONIUM SALTS OF ([(C8H12)IR]5(NB2W4O19)2)3-, ([(C8H12)IR]2H(NB2W4O19)2)5-, AND [(C8H12)IR(P3O9)]2-

Stoichiometric reaction of [(C8H12)Ir(NCCH3)2]PF6 with Nb2W4O19[(n-C4H9)4N]4 in CH2Cl2 yields crystalline {[(C8H12)Ir]5- (Nb2W4O19)2}[(n-C4H9)4N]3 (1). IR and 13C{H} NMR spectroscopy indicate that the anion of 1 is isostructural with the (norbornadiene)rhodium(I) complex |[(C7H8)Rh]5(Nb2W4O19)2}3− (anion of 2) and contains two octahedral Nb2W4O194− ions linked together in a face-to-face fashion by five four-coordinate (C8H12)Ir+ units. Reaction of compound 1 with Nb2W4O19[(n-C4H9)4N]4 and CH3COOH in CH3CN yields {[(C8H12)Ir]2H(Nb2W4O19)2}[(n-C4H9)4N]5 (3) [a = 16.618 (4) Å, b = 16.548 (4) Å, c = 30.729 (6) Å, α = 87.02 (2)°, β = 94.57 (2)°, γ = 114.20 (2)°, triclinic; [formula omitted]]. According to single-crystal diffraction and 17O NMR spectroscopic studies, the anion of 3 contains two Nb2W4O194− ions linked together in an edge-to-edge fashion by two four-coordinate (C8H12)Ir+ units and one proton. The trimetaphosphate complex [(C8H|2)Ir(P3O9)][(n-C4H9)4N]2 4 [a = 11.324 (2) Å, b = 13.288 (2) Å, c = 34.035 (5) Å, β = 101.24 (1)°, monoclinic; [formula omitted]] is prepared from [(C8H12)Ir(NC-CH3)2]PF6 and P3O9[(n-C4H9)4N]3. A single-crystal X-ray diffraction study of compound 4 revealed the presence of discrete [(C8H12)1r(P3O9)]2− anions in which the iridium center is square-pyramidally coordinated, with the two cyclooctadiene olefinic units occupying basal sites and three trimetaphosphate oxygens spanning the remaining basal and apical sites. Addition of 250 equiv of CD3CN/equiv of Ir to CD3NO2 solutions of 1, 3, and 4, all 3.5 mM in Ir, completely decomposes the anion of 1, partially decomposes the anion of 3, but leaves the anion of 4 intact, according to 1H NMR spectroscopic data. © 1990, American Chemical Society. All rights reserved.