Synthesis, structure, and solution dynamics of indenyl rhodium complexes containing bulky phosphine ligands: molecular structures of (eta(5)-1-CH3-C9H6)Rh(eta(2)-C2H4)(PCy3) (Cy = cyclohexyl) and (eta(5)-1-CH3-C9H6)Rh(dcpe) (dcpe = Cy2PCH2CH2PCy2)

Reactions of (eta(5)-1-CH3-C9H6)Rh(eta(2)-C2H4)(2) with PCy3 (Cy = cyclohex yl) acid 1,2-bis(dicyclohexylphosphino)ethane (dcpe = Cy2PCH2CH2PCy2) gave complexes (eta(5)-1-CH3-C9H6)Rh(eta(2)-C2H4)(PCy3) (1) and (eta(5)-1-CH3-C9 H6)Rh(dcpe) (2), respectively, in high yields. Complexes 1 and 2 were chara cterized by x-ray diffraction studies and by multinuclear NMR spectroscopy. Variable temperature P-31{H-1} NMR spectra allowed for evaluation of energ y barriers associated with indenyl ring rotation. While 1 and 2 displayed s imilar degrees of slip-fold distortion with respect to bonding of the inden yl ligand to the RhL2 fragment, a lower energy barrier to ring rotation was calculated for the mixed ethylene-phosphine complex 1. Yellow crystals of 1 are orthorhombic, Pbca with 16 molecules per unit cell of dimensions a = 11.341(3), b = 32.915(10), and c = 29.413(9) Angstrom. Yellow crystals of 2 are triclinic, PT with two molecules per unit cell dimensions a = 9.327(3) , b = 10.117(3), c = 18.934(6) Angstrom, alpha = 104.28(2)degrees beta = 10 1.34(2)degrees and gamma = 92.99(2)degrees.