Novel Counter Ion Effect on the Disruption of the Hornobimetallic Anion, (ŋ5-MeCp)Mn(CO)₂Mn(CO)5-M+(M+=Na+, PPN+) by PR₃(R=C5H5, C₂H5, OCH₃)

Novel Counter Ion Effect on the Disruption of the Hornobimetallic Anion, (ŋ5-MeCp)Mn(CO)₂Mn(CO)5-M+(M+=Na+, PPN+) by PR₃(R=C5H5, C₂H5, OCH₃)

The homobimetallic anion, (η??-MeCp)Mn(CO)₂Mn(CO)??-M??(M??=Na??, PPN??) was disrupted by PR₃(R=C??H??, C₂H??, OCH₃) in THF at various temperatures (r.t -65℃) under the pseudo first order reaction conditions where excess of PR₃was employed under a nitrogen atmosphere. For the reaction involving PPN?? analog. Mn-Mn heterolytic cleavage occurred, leading to PPN+Mn(CO)5 and (η??-MeCp)Mn(CO)₂PR₃as products; however, in case of Na?? analog, Na?? seems to play a novel counter ion effect on the disruption reaction by transferring one terminal CO from the Mn(CO)₃moiety on to the (η??-MeCp)Mn(CO)₂of the corresponding homobimetallic complex, eventually resulting in Na+Mn(CO)₄PR₃and (η??-MeCp)Mn(CO)₃. This reaction is of overall first order with respect to [homobimetallic complex] with the activation parameters (△H??=23.0±0.7kcal/mol, △S??=-8.7±0.8 e.u. for Na?? analog; △H?=28.8±0.4 kcal/mol, △S=15.7±0.6 e.u. for PPN?? analog reaction).