Heterotrinuclear Complexes of the Platinum Group Metals with 2,2′‐Biimidazole as a Bridging Ligand

Abstract

AbstractThe novel trinuclear complexes [(Pt{C6H3(CH2NMe22,6)2})2(μ‐Hbiim)2Os(O=PPh3)2](NO3)(SO3CF3)2 [C6H3(CH2NMe2‐2,6)2 = pincer ligand, H2biim = 2,2′‐biimidazole] and [(PdL)2(μ‐biim)2Os(O=PPh3)2](NO3)3 (L = cod, 1,5‐cyclooctadiene or L = en, ethylene‐1,2‐diamine) were prepared by the reaction of the mononuclear complex [Os(H2biim)2(O=PPh3)2](NO3)3 with [Pt{C6H3(CH2NMe2‐2,6)2}](SO3CF3), or with PdL(NO3)2 (L = cod or L = en), in the presence of a base. The exchange reaction between [Os(Hbiim)2(O=PPh3)2](NO3)3 and [Me2NH2][RhCl4(NHMe2)] led to the formation of [Os(Hbiim)2(O=PPh3)2][RhCl4(NHMe2)]. The solid‐state structures of [Os(Hbiim)2(O=PPh3)2][RhCl4(NHMe2)] and [(Pt{C6H3(CH2NMe2‐2,6)2})2(μ‐Hbiim)2Os(O=PPh3)2](NO3)(SO3CF3)2·4H2O were determined by single‐crystal X‐ray diffraction. The crystals of [Os(Hbiim)2(O=PPh3)2][RhCl4(NHMe2)] are triclinic with a space group P$\bar 1$ , with a = 10.4293(5), b = 10.6365(6), c = 13.0287(7) Å, β = 91.6840(10), γ = 109.8540(10)°, V = 1316.14(12) Å3, Z = 1. The crystals of the complex [(Pt{C6H3(CH2NMe2‐2,6)2})2(μHbiim)2Os(O=PPh3)2](NO3)(SO3CF3)2·4H2O are triclinic with a space group P$\bar 1$ , with a = 12.604(3), b = 13.471(3), c = 14.347(3) Å, β =77.530(5), γ = 66.613(4)°, V = 2005.6(7) Å3, Z = 1. Deprotonation of 2,2′‐biimidazole in the mononuclear osmium complex, followed by coordination to an additional transition metal fragment leads to a modification of the ligand field and a variation of the redox properties of the OsIII center. [{Pd(cod)}2(μ‐biim)2Os(O=PPh3)2](NO3)3 shows significant catalytic activity towards hydrogenation of terminal and cyclic alkenes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)