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Issue 10, 1996
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Two different co-ordination modes of hydrazide ligands in silicon and germanium compounds


The compounds SiCl4 and GeCl4 reacted with Me2NNMeLi in hexane to form dichlorobis(trimethylhydrazido)-silane, SiCl2(NMeNMe2)21 and tetrakis(trimethylhydrazido)germane, Ge(NMeNMe2)42 in 51 and 50% yield, respectively. The liquid 1(m.p. 6 °C) and solid 2(m.p. 73 °C) decompose at temperatures greater than 100 and 140 °C, respectively. Both compounds can be slowly vaporised at ambient temperature in high vacuum. They have been characterised by spectroscopic techniques including NMR (1H, 13C, 29Si), IR, mass and high-resolution mass spectrometry. Evidence for higher co-ordination of the silicon atom occurs from the 29Si chemical shift (δ–44.0). The crystal structure of 1 shows the Nβ atoms of the hydrazide ligands interacting with the silicon atom resulting in a 4 + 2 co-ordination, whereas no Nβ⋯ Ge interactions are detectable in the structure of 2. While the geometry at the Nα atom in 1 is completely planar, that of the corresponding atom in 2 is slightly pyramidal. Ab initio calculations have been carried out for the model systems SiCl2(N2H3)21a, GeCl2(N2H3)21b(both C2v), and Si(N2H3)42a and Ge(N2H3)42b(both S4) up to the MP2/6-31G* level of theory. The results lead to the prediction that the germanium compound analogous to 1 should have Nβ⋯ Ge interactions which are even stronger than the Nβ⋯ Si ones in 1.

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Article type: Paper
DOI: 10.1039/DT9960002095
Citation: J. Chem. Soc., Dalton Trans., 1996,0, 2095-2100

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    Two different co-ordination modes of hydrazide ligands in silicon and germanium compounds

    N. W. Mitzel, B. A. Smart, A. J. Blake, S. Parsons and D. W. H. Rankin, J. Chem. Soc., Dalton Trans., 1996, 0, 2095
    DOI: 10.1039/DT9960002095

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