225245-35-2Relevant articles and documents
Synthesis and structures of tungsten (1-pyridinio)imido complexes and their facile N-N bond cleavage
Ishino, Hiroshige,Tokunaga, Shin'ichi,Seino, Hidetake,Ishii, Youichi,Hidai, Masanobu
, p. 2489 - 2496 (2008/10/08)
The tungsten (1-pyridinio)imido complexes [WX2(NNC5H4OMe)(L)(PMe2Ph) 2]+, [WX2(NNC5H2Me3)(L)(PMe 2-Ph)2]+, and [WCl2{NNC5H2(COOEt)2Ph}(L)(PMe 2Ph)2]+ (X = Cl, Br; L = CO, C2H4, PMe2Ph) were synthesized by the reaction of the salts of pyrylium cations with the hydrazido complexes [WX2(NNH2)(L)(PMe2Ph)2], which were derived from the dinitrogen complex cis-[W(N2)2(PMe2Ph)4]. The complexes obtained were characterized by spectroscopic measurements as well as crystallographic studies of cis,mer-[WBr2(NNC5H4OMe-4)(PMe 2Ph)3]-[PF6], cis,trans-[WCl2(NNC5H4OMe-4)(CO)(PMe 2Ph)2][ClO4], cis,trans-[WCl2(NNC5H2Me 3-2,4,6)(CO)(PMe2-Ph)2][OTf] (OTf = OSO2CF3), and cis,trans-[WCl2(NNC5H4OMe-4)(C 2H4)(PMe2Ph)2][ClO4], which revealed that the N-N bond distances of these (1-pyridinio)imido complexes are shorter than those of the trialkyl- or unsubstituted hydrazidium complexes so far reported. The (1-pyridinio)imido complexes with a π-acidic ligand (CO or C2H4) underwent smooth N-N bond cleavage on reaction with cobaltocene under ambient conditions to liberate the pyridines in moderate to high yields. In some reactions that were conducted in the presence of HNEt3-Cl, the corresponding imido (NH) complexes were recovered as the metal products. The (1-pyridinio)imido complexes also reacted with KOH in MeOH to give the pyridines and ammonia in high yields. These reactions provide the first examples of N-N bond cleavage of well-defined hydrazidium complexes and accomplish the synthesis of pyridines from molecular nitrogen under mild conditions.
