Steric Control of Coordination Geometry in Titanium-Imido Complexes of N,N′-bis(arylimino)acenaphthylene Ligands
摘要:
Titanium complexes of N,N'-bis(arylimino)acenaphthylene (BIAN) alpha-diimine ligands with varied steric profiles have been prepared. Coordination of the BIAN ligand derivatives to TiCl4 afforded the adducts (dpp-BIAN)TiCl4 (1a), (tmp-BIAN)-TiCl4 (1b), and (dmp-BIAN) TiCl4 (1c) (dpp = 2,6-diisopropylphenyl; tmp = 2,4,6-trimethylphenyl; dmp = 3,5-dimethylphenyl). While the least sterically crowded complex 1c is robust toward loss of the diimine ligand, the dpp-BIAN and tmp-BIAN ligands are readily displaced by pyridine from the more crowded derivatives 1a and 1b, respectively. The crowded profiles engendered by the tmp-BIAN and dpp-BIAN ligands result in the formation of five-coordinate titanium-imide complexes, (dpp-BIAN)TiCl2(=(NBu)-Bu-t) (2a) and (tmp-BIAN)TiCl2(=(NBu)-Bu-t) (2b), upon addition of (BuNH2)-Bu-t to solutions of 1a or 1b, respectively. Single-crystal X-ray diffraction studies reveal a square pyramidal coordination environment with an apical imide ligand and a short Ti-N distance, consistent with a Ti-N triple bond. Conversely, the less crowded dmp-BIAN ligand affords a six-coordinate titanium imido complex, (dmp-BIAN)TiCl2(=(NBu)-Bu-t)((NH2Bu)-Bu-t) (4), upon treatment of 1c with (BuNH2)-Bu-t. Surprisingly the imido ligand is coordinated trans to one arm of the diimine. This six coordinate species is fluxional in solution, and exchange and variable temperature H-1 NMR experiments suggest dissociation of the coordinated (BuNH2)-Bu-t ligand to generate a five-coordinate imido intermediate analogous to 2a and 2b.
TiN and ZnSiN2 nanoparticles are obtained via a novel pyridine‐based synthesisroute. This one‐pot liquid‐phaseroute strictly avoids all oxygen sources (including starting materials, surface functionalization, solvents), which is highly relevant in regard of the material purity and material properties. Colloidally stable suspensions of crystalline, small‐sized TiN (5.4±0.4 nm) and ZnSiN2 (5.2±1.1 nm)
TiN 和 ZnSiN 2纳米粒子是通过一种新型的基于吡啶的合成路线获得的。这种一锅液相路线严格避免了所有氧源(包括起始材料、表面功能化、溶剂),这与材料纯度和材料性能高度相关。可以从液相中立即获得小尺寸结晶 TiN (5.4±0.4 nm) 和 ZnSiN 2 (5.2±1.1 nm) 的胶体稳定悬浮液。元素分析和电子能量损失光谱证实了化合物的纯度,特别是不存在氧。所制备的 ZnSiN 2在室温下就显示出淡黄色发射(500-700 nm),其最大值在 570 nm。
The chemical reactivity of tris-(triphenylphosphine)chloroplatinum(II) undecachlorotrititanate, [(C6H5P]3PtCl+Ti3Cl−11
作者:S. Wongnawa、E.P. Schram
DOI:10.1016/s0020-1693(00)89370-6
日期:1979.1
Dolenko; Poleshchuk; Gostevskii, Russian Journal of Coordination Chemistry, 1999, vol. 25, # 10, p. 744 - 747