Observation of a Chloride-Bridged P–P Bond in the Phosphorus Cation [L(Cl)P(μ-Cl)P(Cl)L]+ (L = NHC)

A bridging chloride anion between two electrophilic phosphorus centers was observed for the first time in the molecular structure of the novel P–P bonded cation [LDipp2P2Cl3]+ (2+; LDipp = 1,3-bis­(2,6-diisopropylphenyl)­imidazol-2-ylidene). Cation 2+ is prepared by the reduction of the monophosphorus species [LDippPCl2]+ (1+) with sodium. DFT calculations, AIM and mechanochemical (compliance constants) analyses are used to examine the bonding situation of this unusual species. The monochloro-substituted cation [LDipp2P2Cl]+ (3+) was likewise observed as a reduction product of 1+.