Synthesis of azaphosphiridine complexes 3a-e was achieved via thermal group transfer reaction using 2H-azaphosphirene complex 1 and N-methyl C-aryl imines 2a-e (i) or via reaction of transient Li/Cl phosphinidenoid complex 5 (prepared from dichloro(organo)phosphane complex 4) using 2a-c (ii), respectively. Reaction of complexes 3a,d and trifluoromethane sulfonic acid in the presence of dimethyl cyanamide led to a highly bond- and regioselective ring expansion yielding 1,3,4sigma3lambda3-diazaphosphol-2-ene complexes 8a,d after deprotonation with NEt3. 31P NMR reaction monitoring revealed that protonation of complex 3a yields the azaphosphiridinium complex 6a, unambiguously identified by NMR spectroscopy at low temperature. All isolated products were characterized by multinuclear NMR spectroscopy, IR and UV/Vis (for 3a,d, 6a, 8a,d), MS and single-crystal X-ray crystallography in the cases of complexes 3b-d, 8a and 8d. DFT studies on the reaction mechanism and compliance constants of the model complex of 6a are presented.
Keywords: Density functional calculations / Electron transfer / Single electron transfer reactions / Radical ions / HSAB parametersThe reaction of 3-ferrocenyl-substituted 2H-azaphosphirene complexes 1a-c in the presence of substoichiometric amounts of ferrocenium hexafluorophosphate yields 3,5-diferrocenylsubstituted 2H-1,4,2-diazaphosphole complexes 3a-c and difluoro(organo)phosphane complexes 4a-c. The reaction of 1a,c and [FcH]PF 6 with cyanoferrocene yields 3a,c in a straightforward way. The molecular structures of 3a,c were unambiguously identified by multinuclear NMR spectroscopic experiments, mass spectrometry, and single-crystal Xray diffraction studies. DFT calculations on model complexes
Reaction of C-ferrocenyl-substituted aminocarbene tungsten complex 1 with [bis(trimethylsilyl)methylene]chlorophosphane (2) and triethylamine yielded 2H-azaphosphirene complex 3 in good yield. Reaction of complex 3 with aryl nitriles 4a-c, N-piperidinonitrile (4d), and acetonitrile (4e) in the presence of ferrocenium hexafluorophosphate yielded regioselectively 2H-1,4,2-diazaphosphole complexes 5a-e through single-electron-transfer-induced ring expansion to-
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