Coordinatively and Electronically Unsaturated Tungsten(0) Carbonyl Complexes Stabilized by pi-Donating Amido Ligands

Novel, coordinatively and electronically unsaturated tungsten tricarbonyl dianions of 2-aminophenol and 1,2-diaminobenzene have been synthesized from the reaction of photogenerated W(CO)(5)THF and [Et(4)N][OC(6)H(4)NH(2)] with subsequent deprotonation by [Et(4)N][OH] accompanied by facile CO dissociation, and the reaction of W(CO)(5)THF and 2 equiv of [Et(4)N][NHC(6)H(4)NH(2)], respectively. These air-sensitive derivatives have been fully characterized both in solution (nu(CO) and (13)C NMR) and in the solid-state (X-ray crystallography). These metal dianions which have formally 16e(-) configurations are stabilized by pi-donation from the amido groups of the chelating ligands, as evident from short W-N bond distances. Both solution (nu(CO) and (13)C NMR) and solid-state (W-N vs W-O bond distances) data on these derivatives indicate the amido ligand to be a better pi-donor than the oxo ligand. Complex 2 crystallized in the monoclinic space group P2(1)/n with a = 14.499(5) Å, b = 14.708(5) Å, c = 15.137(4) Å, beta = 114.13(2) degrees, V = 2946(2) Å(3), and d(calc) = 1.433 g/cm(3), for Z = 4. Complex 3 crystallized in the triclinic space group P&onemacr; with a = 11.479(6) Å, b = 11.786(8) Å, c = 13.148(7) Å, alpha = 102.41(5) degrees, beta = 91.27(4) degrees, gamma = 99.96(5) degrees, V = 1708(2) Å(3), and d(calc) = 1.444 g/cm(3), for Z = 2.