Abstract
The reaction of RhCl3 center dot H2O with (Bu2P)-Bu-t(CH2)(5)(PBu2)-Bu-t afforded several complexes including [Rh-III(H)Cl{(Bu2P)-Bu-t(CH2)(2)CH(CH2)(2)(PBu2)-Bu-t}] (1). [(RhHCl2)-H-III{(Bu2P)-Bu-t(CH2)(5)(PBu2)-Bu-t}](2) (2), [(RhCl)-Cl-I{(Bu2P)-Bu-t(CH2)(2)CH=(CHCH2PBu2)-Bu-t}] (3) and [(RhCl)-Cl-I{(Bu2PCH2C)-Bu-t(O)CH=(CHCH2PBu2)-Bu-t}] (4). X-ray crystal structures of 3 and 4 showed that the C=C bond on the C-5 unit of (Bu2P)-Bu-t(CH2)(5)(PBu2)-Bu-t is bound to Rh(I) in a eta(2) configuration. In 4, the Rh atom has a trigonal pyramidal coordination geometry. The X-ray crystal structure of 2 consists of two rhodium(III) centers bridged by two (Bu2P)-Bu-t(CH2)(5)(PBu2)-Bu-t ligands with two phosphorus atoms, one from each ligand, trans to one another. The crystal structure of the rhodium oxygen adduct with 1,3-bis(di-t-butyl-phosphinomethyl)benzene [RhO2{(Bu2PCH2)-Bu-t(C6H3)(CH2Bu2P)-Bu-t}] (5) was also investigated. In this species the O-2 is eta(2) coordinated to the Rh(l) center with asymmetric Rh-O bond lengths (2.087(7) and 1.998(8) angstrom). The O-O bond distance is short (1.337(11) angstrom) with v(o-o) of 990.5 cm(-1). DFT calculations on complex 5 yielded two eta(2)-O-2 structures that differed in energy by only 0.76 kcal/mol. The lower energy one (5a) had near C-2 symmetry, and had nearly equal Rh-O bond lengths, while the higher energy structure (5b) had near C-s symmetry and generally good agreement with the experimental structure. The calculated UV-Vis and IR spectra of complex 5 are in excellent agreement with experiment. (C) 2012 Elsevier Ltd. All rights reserved.