COORDINATION, ISOMERIZATION AND DISRUPTION OF THE LIGANDS PH2PO2C(CH2)NCH=CH2(N = 0 OR 1) - X-RAY CRYSTAL AND MOLECULAR-STRUCTURE OF CHLORO(TETRAPHENYLDIPHOSPHOXANE-K2P,P')(TRIPHENYLPHOSPHINE)RHODIUM(I)-TETRAHYDROFURAN (1/1)

Reaction of Ph2PCl with CH2 = CHCO2H and CH2 = CHCH2CO2H in the presence of triethylamine produces Ph2PO2CCH = CH2 (L) and Ph2PO2CCH2CH = CH2 (L') respectively. Both are found to undergo further intermolecular reaction to produce Ph2PP(O)Ph2. Reaction of L with [RhCl(PPh3)3], 1 mol L per 1 mol Rh, produces [RhCl(PPh3)L] which reverts back to [RhCl(PPh3)3] if left in solution. The compound [RhCl(PPh3)L] contains a bidentate L ligand co-ordinated via the phosphorus atom and the double bond. A similar reaction of L' with [RhCl(PPh3)3] produces [RhCl(PPh3)(Ph2PO2CCH = CHMe)], involving metal-promoted double-bond migration in the L' ligand. Reaction of 2 mol of L per mol of rhodium produces [RhCl(PPh3)(Ph2POPPh2)] involving a metal-promoted disruption of the L ligand to bidentate tetraphenyldiphosphoxane. Reaction of [RhCl(PPh3)(Ph2POPPh2)] with TlPF6 produces [Rh(PPh3)2(Ph2POPPh2)][PF6]. However addition of TlPF6 to the reaction solution of the above 2:1 reaction of L and [RhCl(PPh3)3] results in the isolation of [Rh(PPh3)3(O2CCH2CH2PPh3)][PF6], a complex containing a triphenylphosphoniopropionate ligand, the formation of which involves a major alteration of the L ligand. Reaction, 1 mol ligand per 1 mol Rh, of L and L' with [{RhCl(C8H14)2}2] produces complexes of the form [(RhClL")2], where L" = L or L' in which the mixed anhydride ligand is co-ordinated via the phosphorus atom and the double bond. Reaction of 2 mol of L per mol of Rh with [{RhCl(C8H14)2}2] produces [RhClL2] and [(RhClL)2(Ph2POPPh2)] as its major products. The former is a five-co-ordinate complex containing two bidentate L ligands, the later a binuclear complex containing a tetraphenyldiphosphoxane bridge between the metal centres each of which has a bidentate L ligand co-ordinated to it. All L ligands in these complexes are co-ordinated via the phosphorus atom and the double bond. The complexes have been characterised by spectroscopic means and by an X-ray crystal structure of [RhCl(PPh3)(Ph2POPPh2)].thf (thf = tetrahydrofuran). The crystals are triclinic, space group P1BAR with a = 11.294(4), b = 11.475(6), c = 17.144(9) angstrom, alpha = 102.31(4), beta = 102.71(4), gamma = 74.11(4)-degrees, and Z = 2. The structure was obtained from 2329 reflections measured on an automatic diffractometer and refined to an R' value of 0.075. The RhPOP ring is essentially planar with very small angles at Rh (68.4-degrees) and O (95.4-degrees) so that the two ring phosphorus atoms are brought very close together (2.457 angstrom). Calculations confirm that, despite this short P ... P distance, there is no bonding interaction.