Recent studies on metal and metalloid bis(trimethylsilyl)methyls and the transformation of the bis(trimethylsilyl)methyl into the azaallyl and β-diketinimato ligands |
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Authors: | Michael F Lappert Dian-Sheng Liu |
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Institution: | School of Chemistry and Molecular Sciences, University of Sussex, Brighton BN1 9QJ, UK |
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Abstract: | Recent results (post-1990) on the synthesis and structures of bis(trimethylsilyl)methyls M(CHR2)m (R = SiMe3) of metals and metalloids M are described, including those of the crystalline lipophilic Na(μ-CHR2)]∞, Rb(μ-CHR2)(PMDETA)]2, K4(CHR2)4(PMDETA)2, Mg(CHR2)(μ-CHR2)]∞, P(CHR2)2 (gaseous) and P2(CHR2)4, Yb(CHR2)2(OEt2)2] and {Yb(CR3)(μ-OEt)(OEt2)}2]; earlier information on other M(CHR2)m complexes and some of their adducts is tabulated. Treatment of M(CHR2) (M = Li or K) with four different nitriles gave the X-ray-characterized azaallyls or β-diketinimates
,
and
(LL′ = N(R)C(tBu)CHR, L′L′ = N(R)C(Ph)C(H)C(Ph)NR, LL″ = N(R)C(Ph)NC(H)C(Ph)CHR, R = SiMe3 and Ar = C6H3Me2-2,5). The two lithium reagents were convenient sources of other metal azaallyls or β-diketinimates, including those of K, Co(II), Zr(IV), Sn(IV), Yb(II), Hf(IV) and U(VI)/U(III). Complexes having one or more of the bulky ligands LL′]?, L′L′]?, LL]?, LL″]?, L″L ]?, LL ]? and {N(R)C(tBu)CH}2C6H4-2]2? are described and characterized (LL = N(H)C(Ph)C(H)C(Ph)NH, L″L = N(R)C(tBu)C(H)C(Ph)NR, LL = N(R)C(tBu)CHPh). Among the features of interest are (i) the contrasting tetrahedral or square-planar geometry for
and
, respectively, and (ii) olefin-polymerization catalytic activity of some of the zirconium(IV) chlorides. |
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Keywords: | Silicon Alkali metals Lanthanides Bis(trimethylsilyl)methyls Crystal structures Azaallyls β-Diketinimates |
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