Synthesis and crystal structures of binuclear iridium and rhodium complexes with symmetrical and unsymmetrical bulky siloxide bridges

New binuclear complexes with siloxide bridges: two unsymmetrical [{Rh(cod)}2(μ-OSiMe3)(μ-OSi(OSiMe3)3)] (1) and [{Ir(cod)}2(μ-OSiMe3)(μ-OSi(OSiMe3)3)] (2) and symmetrical iridium complex [{Ir(cod)(μ-OSi(OSiMe3)3)}2] (3) have been synthesized and characterized. The complexes 1 and 2 are highly isostructural, they both crystallize in triclinic space group P1¯, have very similar unit-cell parameters (1: a = 10.4098(7) Å, b = 12.0886(9) Å, c = 16.2361(11) Å, α = 77.547(6)°, β = 85.007(6)°, γ = 79.955(6)°, 2: a = 10.4302(7) Å, b = 12.0346(9) Å, c = 16.2029(11) Å, α = 77.478(6)°, β = 85.217(6)°, γ = 79.877(6)°), while the symmetrically bridged complex 3 crystallizes in non-centrosymmetric monoclinic space group Pn with a = 15.2148(12) Å, b = 10.0059(8) Å, c = 16.9994(12) Å, β = 98.478(6)°. All three complexes have roof-shaped bis-square planar geometry, with roof angles of about 120°. The cod ligands are close to the lowest energy boat C2 conformations.

The article presents synthesis and structural studies of two isostructural rhodium and iridium complexes such as [{Rh(cod)}2(μ-OSiMe3)(μ-OSi(OSiMe3)3)] (1) and [{Ir(cod)}2(μ-OSiMe3)(μ-OSi(OSiMe3)3)] (2) obtained by sequential reaction of appropriate TM chloride precursors ([{M(μ-Cl)(cod)}2], M = Rh, Ir) with different bulky sodium siloxides as well as iridium complex with two identical hindered bridging siloxide ligands: [{Ir(cod)(μ-OSi(OSiMe3)3)}2] (3).Figure optionsDownload as PowerPoint slide