Novel Counter Ion Effect on the Disruption of the Homobimetallic Anion, (￥?5-MeCp)Mn(CO)2Mn(CO)5-M+ (M+=Na+, PPN+a) by PR3 (R=C6H5, C2H5, OCH3)

摘要

The homobimetallic anion, (ョ 5-MeCp)Mn(CO)2Mn(CO)5-M+ (M+=Na+, PPN+) was disrupted by PR3 (R=C6H5, C2H5, OCH3) in THF at various temperatures (r.t. …65∩) under the pseudo first order reaction conditions where excess of PR3 was employed under a nitrogen atmosphere. For the reaction involving PPN+ analog, Mn-Mn heterolytic cleavage occurred, leading to PPN+Mn(CO)5- and (ョ 5-MeCp)Mn(CO)2PR3 as 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)5 moiety on to the (ョ5-MeCp)Mn(CO)2 of the corresponding homobimetallic complex, eventually resulting in Na+Mn(CO)4PR3- and (ョ 5-MeCp)Mn(CO)3. This reaction is of overall first order with respect to [homobimetallic complex] with the activation parameters (ツH×=23.0【0.7 kcal/mol, ツS×= - 8.7【0.8 e.u. for Na+ analog; ツH×=28.8【0.4 kcal/mol, ツS×=15.7【0.6 e.u. for PPN+ analog reaction).