SOLVENT DEPENDENCE OF THE REACTION OF (ETA(5)-C(5)ME(5))IR(CO)(2) WITH ARYLDIAZONIUM IONS - SYNTHESIS AND CHARACTERIZATION OF MONOIRIDIUM AND DIIRIDIUM CARBONYL-COMPLEXES INCLUDING THE X-RAY STRUCTURES OF R(CO))(2)(1-ETA(1)-1,2-ETA(2)-P-C(6)H(4)OME)][BF4] AND -C(5)ME(5))(CO)(2)IR-IR(CO)(CL)(ETA(5)-CSME)][BF4]

Reaction of CpIr(CO)(2) (3, Cp* = eta(5)-C(5)Me(5)) with [N2Ar][BF4] (Ar = p-C(6)H(4)OMe) in acetone at -78 degrees C affords the nitrogen extrusion product [CpIr(CO)(2)(Ar)][BF4] (5), but in dichloromethane it yields a dinuclear product [Cp(Co)(2)Ir-Ir(Cl)(CO)Cp*][BF4] (6). B y carrying out this very reaction in ethanol solution, a nitrogen-reta ined product [CpIr(CO)(OEt)(NHNAr)][BF4] (7) is obtained, containing an aryldiazene ligand. Deprotonation of 7 gives quantitatively the neu tral doubly-bent aryldiazenido complex CpIr(CO)(OEt)(N2Ar) (8). The I R nu(CO) absorptions measured for the dinuclear compound 6 indicate no bridging carbonyl, but a C-13 NMR study in solution shows that 6 is s tereochemically nonrigid at ambient temperature; its three carbonyl li gands are all involved in a fast exchange process, and this process is frozen at -86 degrees C. Exchange of the CO groups via a terminal-bri dging-terminal process accompanied by rotation about the Ir-Ir axis is suggested. The molecular structure of 6 in the solid state has been e stablished by single crystal X-ray crystallographic analysis and is co nsistent with the solution spectra. By reaction of [N2Ar][BF4] with th e dinuclear complex [CpIr(CO)](2) (4) in acetone, the complex r(CO)}( 2)(1-eta(1)-1,2-eta(2)-p-C(6)H(4)OMe)][BF4] (9) with a rare sigma,pi-b ridging aryl group has been obtained and crystallized. The molecular s tructure containing an asymmetric bridging aryl group is established f or 9 in the solid state by a single crystal X-ray crystallographic ana lysis. However, the identical H-1 NMR features observed at ambient tem perature and -90 degrees C in solution (i.e., a singlet resonance for the two Cp ligands and a symmetric AA'BB' pattern for the p-C(6)H(4)O Me) indicate a static or time-averaged symmetrical molecular geometry for 9. Compound 6 crystallizes in the monoclinic space group P2(1)/c w ith a = 10.583(2) Angstrom, b = 14.256(3) Angstrom, c = 16.818(4) Angs trom, beta = 95.91 (2)degrees, V = 2523.9 Angstrom(3), and Z = 4. Refi nement yielded R(F) = 0.027 and R(wF) = 0.033 for 3299 observed reflec tions (I-o greater than or equal to 2.5 sigma(I-o)) of 4427 unique ref lections. Compound 9 crystallizes in the monoclinic space group P2(1)/ n with a = 11.695(2) Angstrom, b = 19.911(3) Angstrom, c = 12.539(2) A ngstrom, beta = 96.54(1)degrees, V= 2900.8 Angstrom(3), and Z = 4. Ref inement yielded R(F) = 0.025 and R(wF) = 0.035 for 3444 observed refle ctions (I-o greater than or equal to 2.5 sigma(I-o)) of 4526 unique re flections.