Coordinatively unsaturated W(IV)-bis(pyridine) complexes, a reactive source of W(IV)

Addition of 2 equiv of a a-donor ligand (L = pyridine, 4-picoline, or quino line) to complexes of the type [W(NPh)-(eta (4)-arene)(o-(Me3SiN)(2)C6H4)] (arene = CH3CH2C6H5 (3), CH3CH2CH2C6H5 (4)) gave the W(IV)L-2 compounds, [W (NPh)(o-(Me3SiN)(2)C6H4)(C5H5N)(2)](5), [W(NPh)(o-(Me3SiN)(2)C6H4)(p-C6H7N) (2)](6), and [W(NPh)(o-(Me3SiN)(2)C6H4)(C9H7N)(2)] (7). Synthesis of compou nds 5 and 6 by Na degrees reduction of [W(NPh)(o-(Me3SiN)(2)C6H4)Cl-2] in t he presence of 3 equiv of L (L = 5, pyridine or 6, 4-picoline) is also pres ented. Compounds 5, 6, and 7 display hindered rotation of the donor ligands about the W-N bonds, resulting from a steric interaction with the Me3Si gr oups of the diamide ligand. The coordinative unsaturation of 5 and 6 has al so been explored. Compounds 5 and 6 readily react with either CO and PMe3 t o generated the six coordinate complexes [W(NPh)(o-(Me3SiN)(2)C6H4)(C5H5N)( 2)(CO)] (8a), [W(NPh)(o-(Me3SiN)(2)C6H4)(C6H7N)(2)(CO)] (8b), [W(NPh)(o-(Me 3SiN)(2)C6H4)(C5H5N)(PMe3)(2)] (10a), and [W(NPh)(o-(Me3SiN)(2)C6H4)(C6H7N) (PMe3)(2)] (10b), respectively.