Structural Tungsten-Imido Chemistry: The Gas-Phase Structure of W(NBu^t)₂(NHBu^t)₂and the Solid-State Structures of Novel Heterobimetallic W/N/M (M = Rh, Pd, Zn) Species

Abstract

The gas-phase (electron diffraction) and solid-state (X-ray) structures of W(NBut)2(NHBut)2 (1) have been determined. In the gas phase, 1 adopts both C1 and C2 conformations in a 69:31 ratio. The solid-state structure is disordered over two equal sites, both showing approximate C2 conformation as in the gas phase; the imido and amido centers are, however, clearly distinguished. Compound 1 has been used to synthesize novel heterobimetallic derivatives W(NBut)4[Rh(COD)]2 (3) and W(NBut)4[Pd(eta3-C3H5)]2 (4) via the dilithiated intermediate Li2[W(NBut)4] (2). In both cases, the [W(NBut)4] moiety bridges the two organometallic fragments. Reaction of 1 with Me2Zn has produced [Me(tBuN)W(mu-NBut)2ZnMe(NH2But)] (5). The structures of 3, 4, and 5 have been determined. Thermal decomposition of 4 under an autogenerated pressure at 700 degrees C has formed the hitherto uncharacterized bimetallic alloy WPd2.

Bis(tert-butylimido)bis(N,O-chelate)tungsten(VI) Complexes: Probing Amidate and Pyridonate Hemilability

“… These complexes exhibit a highly distorted octahedral geometry due to the acute bite angle of the 1,3- N,O -chelated ligands (58.41(7)–60.68(9)°). All N,O -chelated ligands have similar small O–W–N angles (Table ) and are in agreement with the previously reported 1,3- N,O -chelating bite angles. , The tungsten tert -butylimido (W–N) bond distances are also consistent throughout complexes 3 – 6 and range from 1.746(2) to 1.761(2) Å, which are elongated when compared to the starting material 1 (1.708(11) Å) . This change in bond length is expected due to an increase in the coordination number .…”

“…All N,O -chelated ligands have similar small O–W–N angles (Table ) and are in agreement with the previously reported 1,3- N,O -chelating bite angles. , The tungsten tert -butylimido (W–N) bond distances are also consistent throughout complexes 3 – 6 and range from 1.746(2) to 1.761(2) Å, which are elongated when compared to the starting material 1 (1.708(11) Å) . This change in bond length is expected due to an increase in the coordination number . Similar to other reported 6-coordinate bis­( tert -butylimido)­tungsten­(VI) complexes, the W–N–C imido bond angles approach linear bond angles and range from 151.0(2)° to 176.1(2)°. − Complex 3 has a pseudo- C 2 -symmetric O - trans coordination environment of the 1,3- N,O -chelated ligands with shorter W1–O1 and W1–O2 bond lengths of 2.063(2) and 2.061(2) Å, respectively, and longer W1–N1 and W1–N2 bond lengths of 2.345(2) and 2.357(2) Å, respectively.…”

“…34,61 The tungsten tert-butylimido (W−N) bond distances are also consistent throughout complexes 3−6 and range from 1.746(2) to 1.761(2) Å, which are elongated when compared to the starting material 1 (1.708(11) Å). 62 This change in bond length is expected due to an increase in the coordination number. 62 2)°respectively).…”

“…62 This change in bond length is expected due to an increase in the coordination number. 62 2)°respectively). Although these asymmetric tert-butylimido ligands are not observed in the solution phase by NMR spectroscopy, nonequivalent imido bond angles are commonly observed in the solid state and can often result from crystal packing.…”

Electronic Structure of Two Precursors for Nanofabrication: [(CH3)3CN]2W[N(CH3)2]2 and Ti(NMe2)2(NEt2)2

“…This different behavior can be attributed to two effects: the stabilizing pπ→dπ transfer of electron density from nitrogen to vacant metal d orbitals (two-electron, two-orbital interaction) and the destabilizing repulsion between the occupied metal–nitrogen π-bonding orbitals (or σ-orbitals of the alkyl groups) and the nitrogen lone pairs (four-electron, two-orbital interaction) . The low molecular symmetry (C 1 or C 2 point group for the two conformers) of I places no restriction on orbital interactions/mixing . The amine nitrogens are further away from tungsten and from each other (the W–N bonds are 197.8 pm) compared to the imine nitrogens (the WN bonds are 177.2 pm) .…”