Cationic complexes of rhodium(I) and iridium(I) with methyl- and phenylbis(dimethoxyphosphino)amine

Article abstract of DOI:10.1021/om00094a031

The ligand PhN(P(OMe)₂)₂ (L₂) reacts with [Rh(COD)(acetone)_x]ClO₄ to form [Rh(COD)(L₂)]ClO₄, [Rh(L₂)₂]ClO₄, and [Rh₂(L₂)₄(μ-L₂)](ClO ₄)₂ depending on the metal/ligand ratio used. By contrast MeN(P(OMe)₂)₂ (L₂′) only forms [Rh₂(L₂′)₂(μ-L ₂′)₂]²⁺ which was isolated as PF₆^-, BPh₄^-, ClO₄^-, and F₃CSO₃^- salts. Other rhodium complexes of the latter ligand that were synthesized include [Rh(L₂′)(DPPE)]ClO₄, [Rh(L)(L₂′)(DPPE)]ClO₄ (L = CO, P(OMe)₃), and [Rh₂(L₂′)₂(μ-L ₂″)₂](ClO₄)₂ (L₂″ = 2,5-bis(diphenylphosphino)furan). The iridium analogue of the latter was also prepared as were several iridium complexes of MeN(P(OMe)₂)₂ including [Ir(L₂′)(PPh₃)₂]ClO₄, [Ir(L₂′)₂(PPh₃)]ClO₄, [Ir(CO)(L₂′)(PPh₃)₂]ClO₄, [Ir(L₂′)₃]ClO₄, and [Ir(L₂′)(BDPPF)]ClO₄. The last appears to form five-coordinate adducts with O₂ and dimethyl acetylenedicarboxylate. With the exception of these last two, all the five-coordinate complexes prepared are proposed to adopt fluxional trigonal-bipyramidal structures. [Ir(CO)(L₂′)(PPh₃)₂]ClO₄ crystallizes in the monoclinic system with space group P2₁/c, a = 16.067 (2) A?², b = 14.421 (2) A?, c = 1.9574 (4) A?, β = 102.49 (1)°, and Z = 4. Full-matrix least-squares refinement of 341 variables using 5462 data (I > 3σ(I)) led to final values of R and R_w of 0.037 and 0.048, respectively. The perchlorate ion is partially disordered. The complex adopts a distorted trigonal-bipyramidal structure with an equatorial carbonyl ligand. [Rh₂(L₂′)₄](F₃CSO ₃)₂ crystallizes in the monoclinic system with space group P2₁/c, a = 22.676 (4) A?, b = 19.079 (4) A?, c = 12.236 (7) A?, β = 97.12 (3)°, and Z = 4. Full-matrix least-squares refinement of 523 variables using 6097 data (I > 3σ(I)) led to final values of R and R_w of 0.055 and 0.083, respectively. One anion is severely disordered. The dimer cation contains two distorted square-planar rhodium atoms bridged by two MeN(P(OMe)₂)₂ ligands situated cis to one another. The coordination sphere of each metal is completed by a second ligand which chelates resulting in a basket-shaped species.