Unexpected paramagnetism of mono- and polynuclear 18 valence electron metal carbonyl complexes [(CnRn)(CO)2M]k(L), M = chromium, manganese; k = 1, 2, 4. Implications for photoreactivity

Several mono- and polynuclear complexes of the organometallic 16 valence electron fragments (C n R n )(CO) 2 M, M=Cr (n=6, R=H) and Mn(n=5,R=H,Me), with conventional two-electron nitrogen-donor ligands L (acceptor-substituted pyridines η 1,2 -pyrazine) or with η 1,4 -tetracyanoethylene (TCNE) show sizable metal-based paramagnetism is the solid state at room temperature