Tridentate Tertiary Phosphine-Olefin Ligands. 1. Syntheses of (3-(Diphenylphosphino)propyl)(3-butenyl)phenylphosphine, Ph₂PCH₂CH₂CH₂P(Ph)CH₂CH₂CH=CH₂ (ppol), and Some Rh(I) Complexes of ppol and the X-ray Structure of RhCl(ppol)

The synthesis of (3-(diphenylphosphino)propyl)(3-butenyl)phenylphosphine, Ph2PCH2CH2CH2P(Ph)CH2CH2CH=CH2, where Ph = phenyl and where the molecule is abbreviated ppol, is described. This molecule is designed as a tridentate ligand, with cis phosphines and an olefinic portion capable of ligating. The syntheses of several Rh(I) complexes of ppol are described, including RhCl(ppol), [Rh(ppol)(PPh3)] [AsF6], [Rh(CO)(ppol)(PPh3)] [AsF6], and [Rh(CO)2(ppol)] [AsF6], These complexes have been characterized by chemical and spectroscopic means. In addition, the crystal structure of RhCl(ppol) has been determined from counter diffraction data collected at room temperature. The material crystallizes with four molecules in space group C2h5-P2/n of the monoclinic system in a cell of dimensions a = 10.474 (5) Å, b = 16.752 (10) Å, c = 13.487 (7) Å, and /3 = 95.68 (1)°. Full-matrix least-squares refinement of the 148 variables has led to a conventional R index of 0.047 for the 3569 observations. The coordination of the cis P atoms, the olefinic portion of ppol, and the Cl ligand about the central Rh atom is essentially square planar, with the olefinic portion nearly perpendicular to the basal plane. Considerable weakening of the olefin coordination as a result of the trans influence of the phosphine group is observed.