Correlation among alkoxide .fwdarw. tungsten .pi.-bonding, spin state, and reactivity in W(OCH2CF3)2Cl2(PMe2Ph)2

The reaction of WCl 4 (PMe 2 Ph) 2 with 2 equiv of TlOCH 2 CF 3 gives W(OR f ) 2 Cl 2 (PMe 2 Ph) 2 , which is shown by solution spectroscopic and solid-state (X-ray diffraction) methods to have a trans,cis,cis stereochemistry. The resulting ligand field leaves the two d electrons spin-paired in a single orbital, which enhances O→W π-donation and tends to increase the metal valence electron count to (or near) 18. The electron configuration leaves the molecule surprisingly unreactive toward PMe 2 Ph, H 2 , H 2 O, and even O 2