title: Bis[1,3-bis-(2,4,6-trimethyl-phen-yl)-2,3-dihydro-1H-imidazol-2-yl-idene]dinitros-yl(tetra-hydro-borato-κH,H')tungsten(0).
abstract: In the title paramagnetic 19-electron neutral complex, [W(BH(4))(C(21)H(24)N(2))(2)(NO)(2)], the W(0) atom is coordinated by two 1,3-bis-(2,4,6-trimethyl-phen-yl)imidazol-2-yl-idene (IMes) carbene ligands, two NO groups and two H atoms of an η(2)-tetra-hydro-borate ligand. Depending on the number of coordination sites (n) assigned to the BH(4) (-) ligand, the coordination geometry of the W atom may either be described as approximately trigonal-bipyramidal (n = 1) or as very distorted octa-hedral with the bridging H atoms filling two coordination positions (n = 2). In the latter case, the coplanar NO groups and bridging H atoms (r.m.s. deviation = 0.032 Å) form one octa-hedral plane, with mutually trans-oriented carbene ligands. In the crystal, mol-ecules are connected via C-H⋯O inter-actions.
authors.affiliation: Institute of Inorganic Chemistry, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland.
authors.forename: Javier
authors.initials: J
authors.lastname: Fraga-Hernández
authors.forename: Olivier
authors.initials: O
authors.lastname: Blacque
authors.forename: Heinz
authors.initials: H
authors.lastname: Berke