Synthesis and Reactivity of New Cyclomanganated (η⁶-Arene)tricarbonylchromium Complexes

Abstract

(η 6 -Arene)tricarbonylchromium complexes derived from N, N -dimethylbenzylamine or from benzyl methyl thioether undergo a cyclomanganation reaction when treated with PhCH 2 −Mn(CO) 5 in boiling heptane. The manganation process is selective and involves solely aromatic C−H bond activation that yields bimetallic and trimetallic compounds, respectively, when compounds such as [(η 6 -C 6 H 5 CH 2 R)Cr(CO) 3 ] (R = N(CH 3 ) 2, SCH 3 ) and the diamine [{η 6 -C 6 H 4 -1,3-[CH 2 N(CH 3 ) 2 ]}Cr(CO) 3 ] are reacted. Cases of transmetalation reactions consisting of the transfer of a Mn(CO) 4 moiety from one aromatic ligand to another are observed with free aromatic ligands and with chromium π-complexed ligands. Two examples of bimetallic and trimetallic compounds, [(2-η)-Mn{[η 6 -3,5-(CH 3 O) 2 -C 6 H 2 -CH 2 N(CH 5 ) 2 ]Cr(CO) 3 }(CO) 4 ] ( 2 ) and [(4-η:6-η)-{Mn(CO) 4 } 2 {{η 6 -C 6 H 2 -1,3[CH 2 N(CH 3 ) 2 ] 2 }Cr(CO) 3 }] ( 6a ), respectively, were characterized by X-ray diffraction analysis. Both complexes bear distorted Mn(CO) 4 units with the ancillary amino ligand pointing away from the chromium.