Facile addition of E-H bonds to a dicarbondiphosphide

Charge transfer at P atoms in an N-heterocyclic carbene stabilized 6π-electron aromatic dicarbondiphosphide 1 has been observed upon interaction with a variety of small molecule substrates that feature a polar E-H bond (E = C, N, and O). As a result, these P atoms exhibit fleeting nucleophilicity and electrophilicity behaving as potential independent active sites, which effect the spontaneous addition of E-H bonds leading to a series of unsymmetrical 1,3-diphosphetane frameworks bearing P-C (2), P-N (6 and 7), and P-O bonds (8b, 8c, and 9). In addition, 1,3-diphosphetanium salts have been achieved when X-type substituents are weakly coordinating (i.e. [(CN)2CH]- (3), I- (4), and [(PhOH)2PhO]- (10)). The mechanisms of such transformations are investigated using density functional theory calculations.