New molybdenum(0), molybdenum(II), manganese(I), rhenium(I), silver(I), and copper(I) complexes with the 1,3,5-tris(thiocyanatomethyl)mesitylene [Ms(CH2SCN)(3)] ligand have been synthesized and characterized by IR, NMR, and by X-ray diffraction (except for the rhenium complex). The Ms(CH2SCN)(3) ligand coordinated with the molybdenum, manganese, and rhenium carbonyl fragments as a tripodal chelate. With copper and silver, dimeric dicationic species were obtained instead, with the Ms(CH2SCN)(3) ligand acting simultaneously as a bidentate chelate and bridge. The [{Cu(Ms(CH2SCN)(3))}(2)][BAr'(4)](2) (BAr'(4) = tetra(3,5-bis(trifluoromethyl)phenyl)borate) product is an excellent catalyst for cyclopropanation and aziridination of alkenes and cyclopropenation of alkynes by means of carbene- and nitrene-transfer reactions.