Nuclear magnetic resonance study of arene metal tricarbonyl complexes

摘要: The n.m.r. spectra of all the methyl-substituted benzene complexes chromium tricarbonyl, molybdenum and tungsten tricarbonyl have been obtained. unusual features include a large upfield shift alkene proton chemical shifts on complex formation, but within metals order increasing is Cr > W > Mo, non-periodic trend. It has also observed that individual in an unsymmetrical methyl become markedly different contrast to behavior found free arene. Symmetrical metal complexes, other hand, show same symmetry characteristics as arenes, hence, time scale, there no permanent distortion ring. A theory presented, invoking partial three-point bonding M(CO)3 moiety arene This postulated occur most strongly at carbon atoms bearing groups and, consequence, results abno...