Precursors to dinitrogen reduction: structures and reactivity of trans-[Fe(DMeOPrPE)2(eta(2)-H2)H]+ and trans-[Fe(DMeOPrPE)2(N2)H]+.
trans-[Fe(DMeOPrPE)(2)(H(2))H](+) and trans-[Fe(DMeOPrPE)(2)(N(2))H](+) (DMeOPrPE = 1,2-bis(dimethoxypropylphosphino)ethane) were synthesized and their structures determined by X-ray crystallography. These complexes are important species in a dinitrogen reduction scheme involving protonation of an iron(0) dinitrogen complex to produce ammonia. The rates of substitution of the coordinated H(2) and N(2) molecules with acetonitrile were monitored in a variety of organic solvents. The coordinated N(2) substituted approximately 6 times faster than H(2), but surprisingly the solvent had little effect on the observed rates. The results suggest that the H(2) molecule in trans-[Fe(DMeOPrPE)(2)(H(2))H](+) does not participate in hydrogen bonding to the bulk solvent, as was previously observed in the analogous Ru complex. The deprotonation of trans-[Fe(DMeOPrPE)(2)(N(2))H](+) to yield Fe(DMeOPrPE)(2)N(2) was investigated in the presence of a variety of anions, and it was found that the anion facilitates the reaction through an ion-pairing interaction in which the anion removes electron density from the hydride ligand.
Crossland
Justin L
JL
Department of Chemistry, University of Oregon, Eugene, Oregon 97403, USA.
Young
Douglas M
DM
Zakharov
Lev N
LN
Tyler
David R
DR