Protonation of carbene-stabilized diphosphorus: complexation of HP2(+).

Reaction of carbene-stabilized diphosphorus, L:P-P:L (5) (L: = :C{N(2,6-Pr(i)2C6H3)CH}2) with pyridine hydrochloride yields [L:(H)P-P:L]Cl (6), a salt containing the HP2(+) cation--the elusive phosphorus analogue of the well known diazonium cation, HN2(+). In addition to reporting the synthesis and structure, the nature of (6) was further probed by DFT computations. Interestingly, carbenes may be employed to deprotonate (6), affording the starting material (5).