PARAMAGNETIC MONONUCLEAR RHODIUM(II) ORGANOMETALLIC COMPLEXES - X-RAY STRUCTURE OF [RH(C6CL5)2(P(OPH)3)2]

The anionic complexes [NBu4] [Rh(C6Cl5)2(L2)] [L2: 1,5-cyclooctadiene (cod), 1; {P(OPh)3}2, 2; (CO)2,3; (CO)(PPh3),4], obtained from the arylation of [{Rh(mu-Cl)(L2)}2] with LiC6Cl5, serve as precursors to a number of rhodium(II) complexes via oxidation and substitution reactions. The oxidation of 1 and 2 with chlorine gives the neutral rhodium(II) compounds [Rh(C6Cl5)2-(L2)] [L2 = cod, {P(OPh)3}2]. Substitution of cod in [Rh(C6Cl5)2(cod)] by neutral ligands, such as P(OMe)3, PPh3, pyridine (py), 1,2-bis(diphenylphosphino)ethane (dpe), and bis(diphenyl-phosphino)methane (dpm), renders five new neutral rhodium(II) monomer complexes. The compounds have been studied and characterized by IR, NMR, MS, EPR, and CV, and [Rh-(C6Cl5)2{P(OPh)3}2] (6) has been structurally characterized by an X-ray diffraction study. Compound 6 crystallizes in the triclinic space group P1BAR with a = 9.8718(9) angstrom, b = 11.6830(13) angstrom, c = 12.1366(12) angstrom, alpha = 95.465(6)-degrees, beta = 105.824(4)-degrees, gamma = 112.738(5)-degrees, V = 1209.9(2) angstrom3, Z = 1 and R = 0.041 for 3889 observed reflections. This Rh(II) complex exhibits a centrosymmetric square-planar coordination with a trans arrangement of the ligands.