The pH dependent phase transfer of an organometallic complex: synthesis, characterization, and crystal structure of a W(0) tetracarbonyl with an acidic pyridine–imine ligand

Reaction of the asymmetrical pyridine–imine ligand L (where L=benzoic acid, 3-[(2-pyridinylmethylene)amino]) with W(CO)3(EtCN)3 and CO (g) affords a W(0) tetracarbonyl in which the Schiff-base ligand coordinates in a bidentate fashion. The complex was characterized by IR, NMR, and UV–visible spectroscopy and elemental analysis. The solid-state structure of W(CO)4(L), which crystallized in the orthorhombic space group Pbca with unit cell parameters a=22.497(4) Å, b=14.112(6) Å, and c=13.675(3) Å was established by X-ray crystallography. Deprotonation of the –CO2H group on the ligand with base results in the formation of a water-soluble organometallic complex which can be partitioned between organic and aqueous phases in a biphasic system by pH adjustment.