1,3-intramolecular metal shifts in some pentacarbonyl-chromium and -tungsten derivatives of bis-, tris- and tetrakis(methylthio)methane and bis(methylseleno)methane. A dynamic nuclear magnetic resonance investigation

The mononuclear complexes [M(CO) 5 (CH 3 E) n CH 4− n ] ( n = 2, M = Cr and W, E = S and Se; n = 3, M = Cr and W, E = S; n = 4, M = Cr, E = S) have been synthesized and characterized. In addition to the facile atomic inversions of the metal co-ordinated sulphur and selenium atoms, there are intramolecular 1,3-metallotropic shifts among all the available co-ordination sites on each ligand. From dynamic NMR studies activation energies have been determined for these metal commutations.