2-(Diphenylphosphinoyl)propanoate complexes: Crystal structure of tris[2-(diphenylphosphinoyl)propanoato]vanadium(III)

2-(Diphenylphosphinoyl)propanoic acid (Hdpop) has been prepared by a simple one-step procedure. The anion behaves as a versatile bidentate ligand, which co-ordinates to cations of V-III, Cr-III and Fe-III to give octahedral tris(chelate) complexes of the type M(dpop)(3), to Sn-IV to give SnR(3)(dpop) and SnR(2)(dpop)(2) (R = Me or Ph), and to Mo-VI to give cis-[MoO2(dpop)(2)]. The derivative Tl(dpop),on the other hand, appears to de coordinated through the carboxylate group only. The a-hydrogen of the dpop ligands of the molybdenum and thallium complexes undergo a slow and reversible hydrogen-deuterium exchange reaction with deuterio-methanol, and the mechanism of this process is discussed. The structure of V(dpop)(3) . H2O . CH2Cl2, a rare example of a tris(dioxygen) chelate complex of vanadium(III), has been determined by single-crystal X-ray methods. There are two pairs of optical antipodes, Lambda(R,R,R) and Delta(S,S,S), in the unit cell. The arrangement of donors about the metal is facial, with all the six-membered chelate rings adopting boat conformations. All the O-V-O bond angles are close to 90 degrees, and the V-O(P) bond lengths averaging 2.023(2) Angstrom, are slightly longer than those of V-O(C) at 1.979(2) Angstrom.