MOLECULAR-STRUCTURE OF [W(N)(O-2,6-C6H3(I)PR2)(3)](2) - A METAL-NITRIDO COMPOUND WITH A CYCLIC DIYNE STRUCTURE

The compound [W(N)(O-2,6-(C6H3Pr2)-Pr-i)(3)](2) has been studied by si ngle-crystal X-ray diffraction (triclinic, <P(1) over bar>, a = 12.880 (2) Angstrom, b = 14.103(4) Angstrom, c = 20.317(4) Angstrom, alpha = 90.63(2)degrees, beta = 90.72(2)degrees, gamma = 113.82(2)degrees, Z = 2). The structure exhibits the first example of an asymmetric, cyclic M(2)N(2) core, with bond orders that alternate between ca. 3 for the short W-N linkage (d(W-N) = 1.77 Angstrom) and ca. 1 for the longer on e (d(W-N) = 2.02 Angstrom). The H-1 NMR spectrum of the compound sugge sts that the asymmetric, cyclic structure is maintained in solution. T his structure represents the fourth distinct type identified for [W(N) (OR)(3)](x) complexes; in the present case, steric factors appear to p lay a significant role in favoring the observed structure.