Synthesis, characterization, and reactivity of heterodinuclear RuM (M = Cu(I), Ag(I), Au(I), Rh(I), and Ir(I)) and heterotrinuclear RuAg2 and RuRhAg compounds derived from the metal-complex ligand bis(pyrazolato)(p-cymene)(pyrazole)ruthenium(II)

Article abstract of DOI:10.1021/om00004a068

The reaction of the mononuclear ruthenium p-cymene pyrazolate complex [(η⁶-p-cymene)-Ru(pz)₂(Hpz)] (1) (p-cymene = p-isopropylmethylbenzene; Hpz = pyrazole, C₃H₄N₂) with the halide triphenylphosphine complexes [MCl(PPh₃)]_x and KOH led to the corresponding heterodinuclear compounds [(η⁶-p-cymene)Ru(pz)₃M(PPh₃)] (M = Cu (2), Ag (3), Au (4)). In solution, complexes 2-4 showed a dynamic behavior consisting of exchange between terminal and bridging pyrazolate groups accompanied by dissociation of the phosphine ligand. Complex 3 reacted with AgBF₄ and PPh₃ to yield the heterotrinuclear RuAg₂ complex [(η⁶-p-cymene)Ru(μ-pz)₃{Ag(PPh₃)} ₂]BF₄ (5) which was also fluxional. Heterodinuclear derivatives of formula [(η⁶-p-cymene)(pz)Ru(μ-pz)₂ML₂] (M = Rh; L₂ = 1,5-cyclooctadiene (COD) (6), (CO)₂ (7). M = Ir; L₂ = (CO)₂ (8)) have been prepared by treating complex 1 with the appropriate [M(acac)L₂] (acac = acetylacetonate) compounds. The carbonyl complexes 7 and 8 reacted with mono- or diphosphines, rendering [(η⁶-p-cymene)(pz)Ru(μ-pz)₂ML₂] (M = Rh; L₂ = CO, PPh₃ (9), CO, P(OMe)₃ (10), CO, bis(diphenylphosphino)methane (dppm) (11), dppm (14), 1,2-bis(diphenylphosphino)ethane (dppe) (15), cis-1,2-bis(diphenylphosphino)ethylene (dppen) (16), (R)-(+)-1,2-bis(diphenylphosphino)propane (R-prophos) (17a,b). M = Ir; L₂ = CO, PPh₃ (12), CO, dppm (13), dppe (18)). Protonation of 6-9 and 12 with HBF₄ afforded the corresponding cationic complexes [(η⁶-p-cymene)(Hpz)Ru(μ-pz)₂ML₂]BF ₄ (M = Rh; L₂ = COD (19), (CO)₂ (20), CO, PPh₃ (21). M = Ir; L₂ = (CO)₂ (22), CO, PPh₃ (23)). The molecular structure of complex 22 has been determined by X-ray diffraction methods. Crystals are monoclinic, space group P2₁/c, with cell parameters a = 7.9909(6) A?, b = 17.0590(9) A?, c = 19.083(2) A?, β = 93.94(1)°, and Z = 4. The molecule exhibits two bridging pyrazolate groups between the metals. No direct intermetallic interaction is observed, the Ru?Ir distance being 3.6770(6) A?. In the solid state, a clear hydrogen bond is present between one fluorine atom of the tetrafluoroborate anion and the pyrazole ligand. The heterotrinuclear RuRhAg cationic derivatives [(η⁶-p-cymene)Ru{(μ-pz)Ag(PPh₃)}{(μ-pz) ₂RhL₂}]BF₄ (L₂ = COD (24), CO, PPh₃ (25)) have been prepared on the addition of equimolar amounts of AgBF₄ and PPh₃ to complexes 6 and 9, respectively.