The results of four years' work are outlined. Major advances were achieved in the following areas: (1) New arylazo derivatives of molybdenum, (2) new cyclopentadienyl metal nitrosyl derivatives of molybdenum and manganese, (3) new isonitrile derivatives of chromium, molybdenum, and tungsten, (4) trisacetonitrilemetal tricarbonyls of chromium, molybdenum and tungsten as preparative reagents, (5) novel complexes from trifluoroacetonitrile, (6) cyclic acyl derivatives with organonitrogen and organosulfur ligands, (7) metal carbonyl complexes of unsaturated phosphines, (8) new pi-CH3SCH2 derivatives, (9) new complexes with terminal and with bridging methylthio groups, (10) new complexes obtained from bis(trifluoromethyl)dithietene and disodium cis-ethylenedithiolate, (11) new chemistry of the metal carbonyl anions, (12) preparation and reactions of cyclopentadienyl-diiodocarbonylcobalt, (13) new pi-pentamethylcyclopentadienyl derivatives of various metals, and (14) new polynuclear cyclopentadienylmetal carbonyls of iron and cobalt. (Author).