Complexes of electropositive metals with a hemilabile ether phosphine. Crystal structures of [TiCl4L], [FeL2(O3SCF3)2] and [Mo(CO)3L2][L = PhCH2P(CH2CH2OEt)2]
Abstract
New complexes containing some early transition metals with benzylbis(2-ethoxyethyl)phosphine (L) have been prepared. Reaction of this potentially hemilabile terdentate ligand with TiCl4 afforded [TiCl4L]1. The crystal structure shows the metal to have a distorted-octahedral geometry, where the ligand acts as a P,O-bonding chelate. Reaction of 1 with AgBF4 and AgO3SCF3 afforded yellow oils which could not be fully characterised, but are tentatively assigned as [TiCl3L][BF4] and [TiCl3L][O3SCF3] respectively. The reaction of [Cr(MeCN)3(CO)3] with L resulted in the formation of [Cr(CO)4L2]2 in poor yield. This complex can be prepared in high yield by the reaction of [Cr(MeCN)2(CO)4] with L. The reaction of [M(CO)3(C6H3Me3-2,4,6)](M = Mo or W) with L gave the complex fac-[Mo(CO)3L2]3 and [M(CO)4L2](M = Mo 4 or W 5) depending upon reaction conditions. The crystal structure of 3 shows the metal to have a distorted-octahedral geometry, where one L bonds as a P,O chelate and the other as a P-donor. 31P-{1H} NMR spectroscopy indicates this complex to be fluxional in solution, where the two ligands readily interchange at high temperatures. The iron(II) complex [FeL2(O3SCF3)2]6 was prepared by the reaction of L and FeCl2·4H2O with AgO3SCF3. Its crystal structure shows the metal to have a distorted-octahedral geometry with trans ligands (through phosphorus and oxygen) and trans-co-ordinating triflates.