IR spectroscopic investigation into tungsten oxotetrafluoride complexes with phosphoryl-containing ligands

Infrared spectroscopic method was used to study tungsten oxotetrafluoride complexing in acetonitrile solutions with some of phosphoryl-containing compounds: triphenylphosphate (TPP), tributylphosphate (TBP), triethylphosphate (TEP), triphenylphosphineoxide (TPPO), tributylphosphineoxide (TBPO), trioctylphosphineoxide (TOPO), triamylphosphineoxide (TAPO) and hexamethylphosphorus triamide (HMPA). The formation of WOF4OPR3 compounds, in which a molecular ligand is coordinated to a central ion through an O atom of the phosphoryl group and is located in trans-position relative to a multiplybound oxygen atom, was established. It is shown that with an increase in the OPR3 basicity the frequency of valence vibrations of the W=0 and W-F bonds in the complex infrared spectra increases. The relationship between the Δν (W=0) and Δν(W-F) values, and the Kabachnik constants of R3PO was found. The trans-activity series of phosphoryl-containing ligands was established on the basis of infrared spectroscopy data: TAPO > TBPO approximately HMPA > TOPO > TPPO > TBP > TEP > TPP