Synthesis, spectroscopic and structural properties of an unusual series of homoleptic phosphine oxide complexes of the alkaline earth dications

Hursthouse, Michael B., Levason, Wiliiam, Ratnani, Raju, Reid, Gillian, Stainer, Holly and Webster, Michael (2005) Synthesis, spectroscopic and structural properties of an unusual series of homoleptic phosphine oxide complexes of the alkaline earth dications. Polyhedron, 24 (1), 121-128. (doi:10.1016/j.poly.2004.10.009).

Abstract

The distorted tetrahedral [M(OPPh3)(4)](SbCl6)(2) (M = Mg, Ca, Sr) are obtained from MCl2, OPPh3 and SbCl3 in suitable solvent conditions, while Ba2+ gives [Ba(OPPh3)(5)](SbCl6)(2). The chelating o-C6H4(P(O)Ph-2)(2) gives the tris complexes [M{o-C6H4(P(O)Ph-2)(2)}(3)](SbCl6)(2), while under similar conditions the stoichiometries of the products obtained using Ph2P(O)CH2P(O)Ph-2 vary, with M; and products include the five-coordinate [Mg{Ph2P(O)CH2P(O)Ph-2}(2)(H2O)](SbCl6)(2), the distorted octahedral [M{Ph2P(O)CH2P(O)Ph-2}(3)](SbCl6)(2) (M = Ca or Sr) and the seven-coordinate [Sr{Ph2P(O)CH2P(O)Ph-2}(3)(EtOH)](SbCl6)(2). Strontium is unusual in that both six- and seven-coordinate species are evident and may be isolated depending upon the reaction conditions. These are the first reported Group 2 complexes with bidentate phosphine oxides and there are no other phosphine oxide complexes with Sr or Ba. Crystal structures are reported for {Mg(OPPh3)(4)](SbCl6) (2).CH2Cl2 [Ca{Ph2P(O)CH2P(O)Ph-2}(3)] (SbCl6)(2).2CH(2)Cl(2) and [Sr{Ph2P(O)CH2P(O)Ph-2}(3)(EtOH)](SbCl6)(2).0.45CH(2)Cl(2). The compounds isolated show significant dependence upon the charge:radius ratio of the metal and the steric bulk and rigidity of the ligand.

This record has no associated files available for download.

Contributors

Author: Gillian Reid

Download statistics