SYNTHESIS AND STRUCTURE OF [BI-2(N(T)BU)(4)]LI-2(2)CENTER-DOT-2THF - A BIMETALLIC CUBANE FRAGMENT CONTAINING A [BI-2(N(T)BU)(4)](2-) ANION

摘要

The imido-Bi complex [Bi-2(N(t)Bu)(4)]Li-2 . 2THF (1) has been prepared by the in situ reaction of [(Me(2)N)Bi(mu-N(t)Bu)](2) with [(t)BuNHLi] in toluene/THF solution. The complex has been characterised by elemental analysis, solid-state IR spectroscopy, H-1 NMR spectroscopy in solution, and by a low-temperature (153 K) X-ray diffraction study. The complex crystallises in the monoclinic space group P2(1), with cell dimensions a = 11.158(2), b = 16.777(3), c = 17.239(3) Angstrom, beta = 92.45(3)degrees, V = 3224.2(10) Angstrom(3) and Z = 4. Molecules of 1 consist of discrete [Bi2Li2N4] cubane units in the solid state. Further association of these units into a structure akin to the previously characterised complex [Sb-2(NCy)(4)]Li-2(4) (2), consisting of a cage of two interlocked 'broken cubes', is prevented by Lewis base solvation of Li. Solution NMR and cryoscopic studies of 2 show that the complex is involved in a dissociative equilibrium in which separate cubane units, similar to those identified in 1, are formed. [References: 39]