Synthesis, characterization, and x-ray crystal structures of W(VI) alkyl complexes with chelating diamide and imido co-ligands

The complex W(NPh)Cl-2[o-(NSiMe3)(2)C6H4] 3 was synthesized from PhN=WCl4 . OEt2 and N,N'-(Li-2[o-(NSiMe3)(2)C6H4] and reacts with Lewis bases to form the adducts W(NPh)Cl-2[o-(NSiMe3)(2)C6H4](L) (L = PMe3, THF, 3-picoline, (BuNC)-Bu-t, MeCN) 4a-e. Crystals of 4a are triclinic, space group P (1) over bar, with a = 9.562(1), b = 10.277(1), c = 14.920(2) Angstrom, alpha = 82.15(1), beta = 80.18(1), gamma = 80.41(1)degrees, and Z = 2. The structure was solved by the heavy atom method and refined to R = 0.0408 for 4224 observed (I > 2 sigma(I)) reflections. The dialkyl complexes W(NPh)R-2[o-(NSiMe3)(2)C6H4] (R = Me, Et, CH2Ph, CH2CMe3, CH2CMe2Ph) 5-9 are formed through subsequent reactions of 3 with the corresponding Grignard reagent. Crystals of complex 5 are monoclinic, space group P2(1)/n, with a = 10.3545(2), b = 17.9669(1), c = 13.3168(1) Angstrom, beta = 103.826(1)degrees, and Z = 4. The structure of complex 5 was solved by direct methods in SHELXTLS and refined to R = 0.0247 for 4572 observed reflections. Compound 5 has a square pyramidal geometry in which the imido ligand occupies the apical position and reacts with PMe3 to form the adduct W(NPh)Me-2[o-(NSiMe3)(2)C6H4](PMe3) 5a. Crystals of complex 5a are monoclinic, space group C2/m, with a = 13.5336(1), b = 14.3291(1), c = 15.3785(1) Angstrom, beta = 110.365(1)degrees, and Z = 4. The structure of compound 5a was solved by direct methods in SHELXTLS and refined to R = 0.0272 for 3057 observed reflections. Crystals of the bis-neopentyl complex 8 are monoclinic, space group P2(1)/n, with a = 10.6992(4), b = 18.3144(7), c = 16.0726(6) Angstrom, beta = 92.032(1)degrees, and Z = 4. The structure of 8 was solved by direct methods in SHELXTLS and refined to R = 0.0261 for 5881 observed reflections. Complex 8 has a trigonal bipyramidal geometry with both neopentyl groups and one amido nitrogen in the equatorial plane.