Abstract
In this thesis, the sterically hindered three-nitrogen donor ligand H2[N2Ndipp] (N2Ndipp = 4-methyl-2,6-(N-2,6-iPr2C6H3)2 pyridine) was chosen to synthesize low-coordinate multinuclear complexes. Treatment of Li2[N2Ndipp] with GeCl2．dioxane and SnCl2 respectively gives the dinuclear complexes M2[N2Ndipp]2 (1: M = Ge; 6: M = Sn). Upon reduction of 1 by KC8, a dinuclear germanium(I) complex K2Ge2[N2Ndipp]2 (2) is isolated and characterized, where the geometry of the Ge-Ge linkage adopts the first example of cis-bent conformation, and the Ge-Ge bond length is 2.5168(6) Å and recognized as a σ bond. After removing the K+ cation from 2 by 2 equiv of 18-crown-6 ether, the ionic compound [K(18-crown-6)]2Ge2[N2Ndipp]2 (3) was obtained, where the cis-bent geometry is maintained but the Ge-Ge bond length is slightly increased to 2.5371(11) Å by 0.02 Å. On the other hand, reduction of 6 with KC8 in the presence of 18-crown-6 ether only leads to the isolation of a mononuclear tin(II) complex [K(18-crown-6)]2{Sn[N2Ndipp]2} (7). Interestingly, reaction of 2 with GeCl2．dioxane results in the formation of a linear tetranuclear mixed-valence Ge(II)-Ge(I)-Ge(I)-Ge(II) complex (GeCl)2Ge2[N2Ndipp]2 (4), where the internal Ge(I)-Ge(I) bond length is significantly shortened to 2.4071(6) Å and the two external Ge(I)-Ge(II) bond lengths are 2.5169(7) and 2.5196(5) Å. Moreover, reaction of 2 with SnCl2 also produces a tetranuclear mixed-metal complex (SnCl)2Ge2[N2Ndipp]2 (5), which is isostructural with that of 4 and, surprisingly, the internal Ge(I)-Ge(I) bond length dramatically shrinks to 2.3735(6) Å and the two external Ge(I)-Sn(II) bonds length are 2.6807(6) and 2.6807(5) Å. In addition, mixing the deportonated bulky amidinates Li(THF)2[C(R)(N-2,6-iPr2C6H3)2] (R = H, tBu) with AlCl3 gives rise to the formation of mononuclear aluminum complex, AlCl2[C(H)(N-2,6-iPr2C6H3)2] (8a) and AlCl2[C(tBu)(N-2,6-iPr2C6H3)2] (8b). However, attempts to isolate the dinuclear Al(I)-Al(I) bonded complexes upon reduction of 8a and 8b have been unsuccessful. All the said products are fully characterized by NMR spectroscopy and elemental analysis, and their molecular structures are determined by single crystal X-ray crystallography.