Mono and binuclear rhodium dicarbonyl complexes containing the hydridotris(3-p-chlorophenylpyrazol-l-yl)borate ligand (TpPhCl).: X-ray structures of the binuclear complex [(OC)2Rh(μ:κ2,κ1-Tp PhCl)Rh(Cl)(CO)2] and of three isomers of [Rh(κ2-T pPhCl)(CO)2]

Two Rh-dicarbonyl complexes [Rh(kappa(2)-Tp(PhCl))(CO)(2)] (1) and [(OC)(2)Rh(mu:kappa(2),kappa(1) -Tp(PhCl))Rh(Cl)(CO)(2)] (2) have been synthesized and structurally characterized by IR and NMR spectroscopies and X-ray crystallography. Three isomeric forms have been isolated for 1, which showed different environment on the Rh centre related with the uncoordinated third pyrazolyl arm. So, it was rotated to the equatorial position in 1-A, but occupied the axial position in 1-B and 1-B' with different orientation. As a consequence, two square-planar coordination geometries (one with the third pyrazolyl ring over the square-plane (SP1) and the other inverted with the free pyrazolyl arm away from the square-plane (SP2)) and one square pyramidal geometry (SPy) have been established for 1-B, 1-A and 1-B', respectively. The X-ray structure of 2 indicates a bridging coordination of the Tp(PhCl) ligand, being kappa(2) to the [Rh(CO)(2)] fragment and kappa(1) to the [Rh(Cl)(CO)(2)] group. (C) 2003 Elsevier Ltd. All rights reserved.