Solvent Effects on Hydride Transfer from Cp*(P-P)FeH to BNA⁺ Cation

Examining of the hydride transfer reaction between Cp*­(Ph2PNtBuPPh2)­FeH (Ph2PNtBuPPh2 = N,N-bis­(diphenylphosphanyl)tert-butylamine, 1-H) and 1-benzyl-3-carbamoylpyridinium cation (BNA+) in different solvents, we found that the solvents exert considerable influence on the hydride transfer processes. A coordinating solvent molecule such as MeCN is not only a ligand which stabilizes the organo-iron fragment producing [Cp*­(Ph2PNtBuPPh2)­Fe­(NCMe)]+ ([1(NCMe)]+), but also assists the hydride transfer. In THF, reaction of 1-H with BNA+ under high pressure of nitrogen (60 psi) giving the iron­(II)–nitrogen complex [Cp*­(Ph2PNtBuPPh2)­Fe­(N2)]+ ([1-N2]+) and BNAH. In CH2Cl2, [1-N2]+ catalyzes the conversion of 1-H to Cp*­(Ph2PNtBuPPh2)­FeCl (1-Cl), which hampers the expected hydride transfer reaction. In the presence of MeCN, the hydride transfer process in THF, CH2Cl2, or benzene was achieved affording the reduced BNAH and [1(NCMe)]+. New iron complexes in the [Cp*­(Ph2PNtBuPPh2)­FeX]n+ series (where n = 0, X = H or Cl; n = 1, X = MeCN, N2, or Cl–) were obtained and well characterized.