Synthesis of (1-Adamantylimido)vanadium(V)-alkyl Complexes Containing a Chelate Alkoxo(imino)pyridine Ligand, and Reactions with Alcohols (ROH) That Proceed via Intermediates Formed by Coordination of ROH

An (1-adamantylimido)vanadium(V)-dialkyl complex containing a chelate alkoxo(imino)pyridine ligand, V(NAd)(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>2</sub>(L) [<b>2</b>, Ad = 1-adamantyl, L = 6-OC(Me)<sub>2</sub>-2-{(2,6-<sup><i>i</i></sup>Pr<sub>2</sub>C<sub>6</sub>H<sub>3</sub>)NCMe}-C<sub>5</sub>H<sub>3</sub>N], has been prepared, and some reactions with (CF<sub>3</sub>)<sub>2</sub>(CH<sub>3</sub>)COH, (CF<sub>3</sub>)<sub>2</sub>CHOH, 2,6-Me<sub>2</sub>C<sub>6</sub>H<sub>3</sub>OH, and 2,6-Me<sub>2</sub>C<sub>6</sub>H<sub>3</sub>SH in C<sub>6</sub>D<sub>6</sub> have been explored. Two alkyl groups in <b>2</b> take a <i>trans</i> form, as determined by the dichloride analogue V(NAd)Cl<sub>2</sub>(L) (<b>1</b>), and no reaction took place or afforded a negligible amount of the product even if the C<sub>6</sub>D<sub>6</sub> solution containing <b>2</b> and PMe<sub>3</sub> (13 equiv) or NHC [2.1 equiv, NHC = 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene] was heated at 80 °C for 72 h. The reaction of <b>2</b> with (CF<sub>3</sub>)<sub>2</sub>CHOH and (CF<sub>3</sub>)<sub>2</sub>(CH<sub>3</sub>)COH at 25 °C afforded intermediates V(NAd)(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>2</sub>(L)[ROH] [R = CH(CF<sub>3</sub>)<sub>2</sub>, C(CF<sub>3</sub>)<sub>2</sub>(CH<sub>3</sub>)], and the resultant species were converted to the original complex <b>2</b> if the mixed solutions were placed <i>in vacuo</i> (to remove volatiles). The reactions with ROH upon heating or by stirring for longer hours afforded the monoalkyl-alkoxo species V(NAd)(CH<sub>2</sub>SiMe<sub>3</sub>)(L)(OR) [R = CH(CF<sub>3</sub>)<sub>2</sub> (<b>4</b>), C(CF<sub>3</sub>)<sub>2</sub>(CH<sub>3</sub>) (<b>5</b>)]; complex <b>4</b> determined by X-ray crystallography has a distorted tetrahedral geometry around vanadium. It has thus been proposed that reactions of the dialkyl complex <b>2</b> with ROH proceeded via pentacoordinated intermediates formed by coordination of ROH, accompanied by dissociation of two neutral nitrogen donors in the chelate ligand.