Silene theoretical prediction

As discussed in Section II. A, theoretical studies predicted that phospha-silenes with silyl substituents attached to phosphorus should have planar, trigonally coordinated silicon, with the Si—P w-bonds strengthened by the hyperconjugative influence of the silyl group.16 Recently, this was proved by a single-crystal X-ray structure determination of the derivative... 

The calculated Si=C bond lengths in trans-bent silynes are distinctively shorter than Si=C bond lengths in silenes (i.e. 1.632 A and 1.714 A in HSi=CH and in H2Si=CH2, respectively, at MP2/6-31G )2970. A theoretical analysis in the framework of natural bond theory predicts for 668b and substituted derivatives bond orders for the SiC bond which are intermediate between double and triple bonds with considerable ionic contributions29711 0. 

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