85201-90-7Relevant academic research and scientific papers
Cycloaddition reactions of platinum(II)-η1-allyl complexes with tetracyanoethylene
Calligaris,Carturan,Nardin,Scrivanti,Wojcicki
, p. 865 - 873 (2008/10/08)
Tetracyanoethylene (TCNE) reacts with the 16-electron complexes [(η1-C2H5)PtL2Cl] (1a-d, L = PPh3, PMePh2, P-C-Hx3, or 0.5Ph2PCH=CHPPh2, respectively) to afford products of [3 + 2] cycloaddition to the allyl fragment [CH2C(CN)2C(CN)2CH2CHPtL 2Cl] (2a-d). These cycloadducts were characterized by 1H NMR, 31P NMR, and IR spectroscopy; in addition, the structures of the L = P-c-Hx3 (2c) and 0.5Ph2PCH=CHPPh2 (2d) products were determined by single-crystal X-ray diffraction techniques. 2c crystallizes in the space group C2/c with a = 19.13 (2) A?, b = 21.01 (2) A?, c = 13.92 (2) A?, β = 108.9 (2)°, V = 5297 A?3, and Z = 4; 2d crystallizes in the space group P21/c with a = 8.721 (8) A?, b = 16.00 (1) A?, c = 26.52 (2) A?, β = 100.1 (1)°, V = 3643 A?3, and Z = 4. Low-temperature 31P NMR studies of the reactions of 1a-d with TCNE in CD2Cl2 show that the formation of 2c and 2d occurs without any detectable intermediates; by contrast, the formation of each of 2a and 2b takes place via two observable species. The results suggest that the cycloaddition proceeds by at least two different mechanisms which depend on the nature of the ligated phosphine. Possible pathways are proposed.
