Phosphorus gallium-carbon bonds

The deshielded 31P and 13C NMR chemical shifts observed for 41-43 ( 31P +130, 13C +76, /PC 85 Hz) are consistent with the presence of a P = C double bond and positive charge development at phosphorus these spectroscopic data are in fact very similar to those observed for the methylenephosphonium salt 40.59,6° This similarity is reinforced by the X-ray analysis of the gallium adduct 42 (Fig. 4) (i) The phosphorus and carbon atoms adopt a trigonal planar geometry, (ii) there is a twist angle between the two planes of 34.1°, and (iii) the phosphorus-carbon bond distance is rather short (1.61 A). 

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