104034-15-3Relevant academic research and scientific papers
Reduction chemistry of Fe2(NO)4(μ-PR2)2 (R = Ph, Cy) and protonation and alkylation of resultant binuclear iron nitrosyl anions
Yu, Yuan-Fu,Chau, Chung-Nin,Wojcicki, Andrew
, p. 4098 - 4104 (2008/10/08)
Reduction of Fe2(NO)4(μ-PPh2)2 (1) with Na, Na/Hg, LiAlH4, or Red-Al proceeds with cleavage of the Fe-Fe bond to yield [(NO)2Fe(μ-PPh2)2Fe(NO)2] 2- (2). By contrast, reduction of 1 or Fe2(NO)4(μ-PCy2)2 with MBEt3*H (M = Li, Na, K; * H = H, D (with 1 only)) occurs by transfer of *H- to generate [(NO)2Fe(μ-PR2)(μ-NO)Fe(NO)(PPh 2*H)]- (R = Ph (3), Cy). Deprotonation of 3 with n-BuLi at -78°C yields [(NO)2Fe(μ-PPh2)(μ-NO)Fe(NO)(PPh2)] 2- (4), which isomerizes to 2 at -70 °C. Reaction of 1 with MeLi proceeds analogously to that with MBEt3H and results in the formation of [(NO)2Fe(μ-PPh2)(μ-NO)Fe(NO)(PPh 2Me)]- (5-Me). The anions 2-5 react with CF3COOH and alkyl (generally, Me, Et, CH2Ph, CH2C-H=CH2, CH2CHCH2CH2, inter alia) iodides (and bromides and triflates, in some cases) at temperatures of -78 to +257deg;C to yield binuclear and mononuclear products. Thus, 2 and 4 are protonated by 1 equiv of acid to 3 and alkylated by 1 equiv of alkylating reagent to 5. The reaction of 2 with MeI or MeOS(O)2CF3 was shown spectroscopically (31P and 2H NMR) at low temperatures to proceed by the intermediacy of a species formulated as [(NO)2(Me)Fe(μ-PPh2)2Fe(NO) 2]- (6), which at -15 °C converts to 5-Me. The anions 3 and 5 undergo protonation and alkylation with fragmentation of the binuclear framework to give mononuclear complexes Fe(NO)2(PPh2H)2, Fe(NO)2(PPh2H)(PPh2R), or Fe(NO)2(PPh2R)(PPh2R′) (same or different R and R′), depending on the reaction, and 1. Probable mechanisms of the foregoing reactions are discussed and compared with those of the corresponding reactions of the binuclear iron carbonyl anions derived from Fe2(CO)6(μ-PR2)2 (R = Ph, Me). The relative propensities of the protonated or alkylated (R′) intermediates to undergo migratory insertion of CO or NO vs. reductive elimination of Fe(PR2H) or Fe(PR2R′) play an important role in determining the course of these reactions of the binuclear anions.
