Spectroscopic Study of Dehydrochlorination and Exchange with D2 in WH2Cl2(PMe2Ph)4: Unexpected Stereochemical Rigidity of Dodecahedra Containing both Hydride and Chloride Ligands. Crystal and Molecular Structure of W(H)3(.eta.2-C6H4PMe2)(PMe2Ph)3

C−O Bond Homolysis in a Tungsten Alkoxide: The Mechanism of Alcohol Deoxygenation by WCl2(PMe3)4 and WH2Cl2(PMe3)4

“… The PhCH 2 OH oxidative addition appears to be reversible as H/D exchange is observed by 1 H and 2 H NMR in reactions of WD 2 Cl 2 (PMe 3 ) 4 + PhCH 2 OH and WH 2 Cl 2 (PMe 3 ) 4 + PhCH 2 OD. A similar mechanism of reversible phosphine loss anddihydrogen oxidative addition has been proposed by Caulton and co-workers to explain isotopic exchange between D 2 and the closely related WH 2 Cl 2 (PMe 2 Ph) 4 but the chloride derivatives are unstable to reductive elimination.…”

“…1 H{ 31 P} NMR shows the formation of WHDCl 2 (PMe 3 ) 4 ( 2 - d 2 ) as the reaction proceeds. Species 2 - d 1 exhibits an intrinsic upfield isotopic shift of 42 ppb in the hydride resonance vs 2 , higher than the 20 ppb shift reported for WH 2 Cl 2 (PMe 2 Ph) 4 …”

“…WH 2 Cl 2 (PMe 3 ) 4 ( 2 ) and WH 2 Cl 2 (PMePh 2 ) 4 are formed by H 2 oxidative addition, , but 4 + H 2 does not give WH 2 Cl 2 (PMePh 2 ) 4 .…”

False Minima in X-ray Structure Solutions Associated with a “Partial Polar Ambiguity”: Single Crystal X-ray and Neutron Diffraction Studies on the Eight-Coordinate Tungsten Hydride Complexes, W(PMe3)4H2X2 (X = F, Cl, Br, I) and W(PMe3)4H2F(FHF)

“…Although 8-coordinate hydride complexes of the composition W(PR 3 ) 4 H 2 X 2 have been known since the early 1980s, only the fluoro and chloro derivatives have been previously reported. Specifically, the fluoro complex W(PMe 3 ) 4 H 2 F 2 was synthesized by Green via reaction of W(PMe 3 ) 4 (η 2 -CH 2 PMe 2 )H with HF(aq) followed by treatment with KH, while the chloro analogue W(PMe 3 ) 4 H 2 Cl 2 was prepared by a variety of methods including (i) oxidative addition of H 2 to W(PMe 3 ) 4 Cl 2 , − (ii) Na(Hg) reduction of W(PMe 3 ) 3 Cl 4 in THF in the presence of excess PMe 3 under an atmosphere of H 2 , and (iii) reaction of W(PMe 3 ) 4 Cl 2 with methanol, in which case it was obtained as a mixture with W(PMe 3 ) 3 (O)Cl 2 . − As an extension of Green's method, we have found that W(PMe 3 ) 4 H 2 Cl 2 may also be prepared in high yield (ca. 80%) by the direct reaction of W(PMe 3 ) 4 (η 2 -CH 2 PMe 2 )H with aqueous hydrochloric acid (Scheme ) …”

“…The structures are, therefore, as first noted by Sharp for the chloro derivative W(PMe 3 ) 4 H 2 Cl 2 , static on the NMR time scale at room temperature. Caulton has noted that the analogue W(PMe 2 Ph) 4 H 2 Cl 2 is also stereochemically rigid on the NMR time scale at room temperature 17a. More impressively, Caulton has also reported that the trihydride W(PMe 2 Ph) 4 H 3 Cl is stereochemically rigid on the time scale of 1 day, as judged by the rate of isomerization of selectively deuterated W(PMe 2 Ph) 4 H 2 DCl 17a…”