A study of β-hydride abstraction from alkanediyl homobimetallic complexes [{Cp(CO)2Fe}2{μ-(CnH2n)}] (n=4–10, Cp=η5-C5H5)
作者:Evans O. Changamu、Holger B. Friedrich
DOI:10.1016/j.jorganchem.2006.11.017
日期:2007.2
The alkyl-bridged iron(II) Complexes [CP(CO)(2)Fe}(2)(mu-(CnH2n)}] (n = 6-10, Cp = eta(5) -C5H5) undergo both single and double hydride abstraction when reacted with one equivalent of Ph3CPF6 to give both the monocationic complexes, [CP(CO)(2)Fe}(2)mu-(CnH2n-1)}]PF6, and the dicationic complexes, [CP(CO)(2)Fe}(2)mu-(CnH2n-2)}](PF6)(2). The ratios of monocationic to dicationic complexes decrease with the increase in the value of n. The complexes where it = 4 and 5 undergo only single hydride abstraction under similar conditions. When reacted with two equivalents of Ph3CPF6, the complexes where n = 6-10 undergo double hydride abstraction to give dicationic complexes only. In contrast, the complex where n = 5 gives equal amounts of the monocationic and the dicationic complexes, while the complex where n = 4 only gives the monocationic complex. H-1 and C-13 NMR data show that in the monocationic complexes one metal is cy-bonded to the carbenium ion moiety while the other is bonded in a eta(2)-fashion forming a chiral metal] acylopropane type structure. In the dicationic complexes both metals are bonded in the eta(2) -fashion. The monocationic complexes where n = 4-6, react with methanol to give ill-alkenyl complexes[Cp(CO)(2)Fe(CH2)(n)CH=CH2] (eta = 2-4) as the major products and sigma-bonded ether products [CP(CO)(2)-Fe}(2)mu-(CH2)(n),CH(OCH3)CH2)] as the minor products. The complex where n = 8 reacted with iso-propanol to give the eta(1)-alkenyl complex [CP(CO)(2)Fe(CH2)(6)CH=CH2]. The dicationic complexes where n = 5, 8 and 9 were reacted with NaI to give the respective alpha,omega-diencs and [CP(CO)(2)FeI]. (c) 2006 Elsevier B.V. All rights reserved.