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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 19, Number 4
BKCSDE 19(4)
April 20, 1998 

Novel Counter Ion Effect on the Disruption of the Homobimetallic Anion, (η5-MeCp)Mn(CO)2Mn(CO)5-M+ (M+=Na+, PPN+a) by PR3 (R=C6H5, C2H5, OCH3)
Yong Kwang Park*, Seon Joong Kim, Chang Hwan Rhee
The homobimetallic anion, (η 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 (η 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 (η5-MeCp)Mn(CO)2 of the corresponding homobimetallic complex, eventually resulting in Na+Mn(CO)4PR3- and (η 5-MeCp)Mn(CO)3. This reaction is of overall first order with respect to [homobimetallic complex] with the activation parameters (ΔH≠=23.0±0.7 kcal/mol, ΔS≠= - 8.7±0.8 e.u. for Na+ analog; ΔH≠=28.8±0.4 kcal/mol, ΔS≠=15.7±0.6 e.u. for PPN+ analog reaction).
462 - 466
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