Oxidative Addition of Nitrosobenzene Fragments across the Triply Bonded Ditungsten Hexa-tert-butoxide Molecule. The Preparation and Structure of 2(μ-O)(μ-OCMe3)2

Article abstract of DOI:10.1021/ja00323a026

W2(OCMe3)6 reacts with nitrobenzene in toluene at 45 deg C over a period of 12 h to give 2(μ-O)(μ-OCMe3)2 in 55-60 percent yield.The molecule consists of face-sharing octahedra with two tert-butoxide units and an oxygen atom as the bridging groups.The tungsten-to-tungsten distance is 3.059 (0( Amgstroem.The W-O distances for μ-O are 1.937 (4) and 1.937 (4) Angstroem, while the W-O distances for the oxygen atoms of the bridging tert-butoxide groups are W(1)-O(6) = 2.078 (4) Angstroem, W(2)-O(6) = 2.269 Angstroem and W(1)-O(7) = 2.264 (4) Angstroem, W(2)-O(7) = 2.092 (4) Angstroem.The W-N distances are 1.737 (5) Angstroem, and 1.738 (5) Angstroem, and the W-N-C angles have an average value of 164.7 <3> deg.The compoud crystallizes in space group C2/c with a = 27.57 (1) Angstroem, b = 18.09 (1) Angstroem, c = 18.36 (1) Angstroem, β = 115.97 deg, V = 8231 (8) Angstroem³, and Z = 8.The tungsten atoms have formal oxidation numbers of VI and no W-W bond exists, the relatively short W-W separation being attributable to the presence of bridging ligands and the role of the ligated oxygen and nitrogen atoms in reducing the effective charge on the metal atoms through extensive ? donation.From the bond lengths and angles it is concluded that the W-N bonds have an order of ca. 2.5, wich includes about one-half of a N -> W ? donor bond over and above the basic W=N double bond.The oxygen atoms, especially those of the terminal alkoxy ligands, also contribute significant ? density to the metal atoms.