Phosphoryl pseudohalides

All X3PO molecules have a pyramidal PX3 group, with the oxygen atom occupying the fourth position to complete a distorted tetrahedron. The P—O bond lengths are about 1.55 A, consistent with the existence of double bonds. Several mixed phosphoryl halides, phosphoryl pseudohalides, as well as X3PS and X3PSe compounds are also known. All of these compounds are prone to ready hydrolysis. 

The corresponding phosphoryl and thiophos-phoryl pseudohalides are also known, i.e. P0(NC0)3, PS(NC0)3, etc. Preparations are by standard procedures such as those on the diagram for PCI3 (p. 497). As indicated there, P(CN)3 has also been made it is a highly reactive white crystalline solid mp 203° which reacts violently with water to give mainly phosphorous acid and HCN. 

Table 12.4 Some phosphoryl and thiophosphoryl halides and pseudohalides...

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