Centre for Catalysis Research and Innovation and Department of Chemistry, University of Ottawa, Ottawa, Ontario, K1N 6N5.
Dalton Trans. 2010 Feb 7;39(5):1266-72. doi: 10.1039/b920047a. Epub 2009 Nov 24.
Attempted coordination of "Ga(I)I" with two new sterically bulky, aryl substituted bis(imino)pyridine ligands lead to Ga(III) species [2,6-{ArN=CPh}(2)(NC(5)H(3))]GaI(2)(+)GaI(4)(-) (Ar = 2,5-(t)Bu(2)C(6)H(3), 2,6-(i)Pr(2)C(6)H(3) = Dipp) arising from thermodynamically favorable disproportionation reactions. Examination of these reactions lead to isolation of a neutral radical species [2,6-{DippN=CPh}(2)(NC(5)H(3))]GaI(2). Both EPR spectroscopy and DFT calculations on this compound indicate that the unpaired electron is localized in a di(imino)pyridine pi* orbital of an anionic ligand with nearly zero contribution from the Ga or I centers. Reaction of {2,5-(t)Bu(2)C(6)H(3)N=CPh}(2)(NC(5)H(3)) with AlCl(3) yielded an analogous Al(iii) product, [{2,5-(t)Bu(2)C(6)H(3)N=CPh}(2)(NC(5)H(3))]AlCl(2)(+)AlCl(4)(-).
试图用两个新的空间位阻大的芳基取代双（亚氨基）吡啶配体来协调“Ga(I)I”，导致 Ga(III)物种 [2,6-{ArN=CPh}(2)(NC(5)H(3))]GaI(2)(+)GaI(4)(-)（Ar = 2,5-(t)Bu(2)C(6)H(3, 2,6-(i)Pr(2)C(6)H(3) = Dipp) 出现，这是热力学有利的歧化反应的结果。对这些反应的研究导致分离出中性自由基物种 [2,6-{DippN=CPh}(2)(NC(5)H(3))]GaI(2)。该化合物的电子顺磁共振波谱和密度泛函理论计算表明，未成对电子定域在阴离子配体的二（亚氨基）吡啶 pi*轨道中，几乎没有来自 Ga 或 I 中心的贡献。{2,5-(t)Bu(2)C(6)H(3)N=CPh}(2)(NC(5)H(3))与 AlCl(3)反应生成类似的 Al(iii)产物 [{2,5-(t)Bu(2)C(6)H(3)N=CPh}(2)(NC(5)H(3))]AlCl(2)(+)AlCl(4)(-)。
