Diazaallyls of group 4 metals based on trans-1,2-diaminocyclohexane
作者:Edward J. Crust、Ian J. Munslow、Peter Scott
DOI:10.1016/j.jorganchem.2005.04.019
日期:2005.7
Amination of 1-bromo-2-methylpyridine with trans-1,2-diaminocyclohexane gives the corresponding bis(aminopyridine) H-V. Conversion of the same diamine to the N,N'-bis(amino-4,4-dimethylthiazoline) H2L2 is also completed in three steps. The analogous aminooxazoline is however inaccessible, although the aminocyclohexane analogue is prepared readily. The proligand FIX forms bis(aminopyridinato) alkyl complexes of the type [(ZrLR2)-R-1] (R = CH2Ph, CH2But). The molecular structure of the neopentyl complex shows that the chiral backbone leads to a puckering of the N4Zr coordination sphere, which contrasts with the related cyclohexyl-bridged Schiff-base complexes which are essentially planar. [ZrL2(CH2But)(2)]- the first aminothiazolinato complex - is formed similarly. A comparison of the structures of [ZrL1(CH2But)(2)] and [ZrL2(CH2But)(2)] indicates that the latter has a fully delocalised N-C-N system, rather similar to a bis(amidinate). Reaction of H2L2 with [Ti(NMe2)(4)] gives [TiL2(NMe2)(2)] which appears to be C-2-symmetric like the above complexes according to NMR spectra, but has one uncoordinated thiazoline unit in the solid state. This is a result of increased ring strain at the smaller titanium metal centre. (c) 2005 Elsevier B.V. All rights reserved.