Preparation, facile deprotonation, and rapid H/D exchange of the mu-hydride diiron model complexes of the [FeFe]-hydrogenase containing a pendant amine in a chelating diphosphine ligand.
The CO-displacement of [(mu-pdt)Fe(2)(CO)(6)] with (Ph(2)PCH(2))(2)N(n-Pr) in refluxing toluene gave an unsymmetrical chelating complex [(mu-pdt){Fe(CO)(3)}{Fe(CO)(kappa(2)-Ph(2)PCH(2)N(n-Pr)CH(2)PPh(2)}] (1) as a major product, together with a small amount of the symmetrical intramolecular bridging complex [(mu-pdt){mu-Ph(2)PCH(2)N(n-Pr)CH(2)PPh(2)}{Fe(CO)(2)}(2)] (2) and the intermolecular bridging complex [{mu,kappa(1),kappa(1)-Ph(2)PCH(2)N(n-Pr)CH(2)PPh(2)}{(mu-pdt)Fe(2)(CO)(5)}(2)] (3). In contrast, the reaction of [(mu-pdt)Fe(2)(CO)(6)] with (Ph(2)PCH(2))(2)NR (R = n-Pr, Ph) afforded the intermolecular bridging isomers 3 and 4 in the presence of a CO-removing reagent Me(3)NO.2H(2)O in CH(3)CN at room temperature. The molecular structures of 1, 3, and 4, as well as the doubly protonated complex [1(H(N)H(mu))](OTf)(2)] were determined by X-ray analyses. The protonation processes of 1 with HBF(4).Et(2)O and HOTf were studied in different solvents. The presence of the H(mu)...H(N) interaction in [1(H(N)H(mu))](2+) was studied by relaxation time T(1) and spin saturation transfer measurements. The mu-hydride of [1(H(mu))](+) and [1(H(N)H(mu))](2+) undergo facile deprotonation with aniline and rapid H/D exchange with deuterons in solution. In contrast, neither deprotonation nor H/D exchange was detected for [(mu-H)(mu-pdt){Fe(CO)(3)}{Fe(CO)(kappa(2)-dppp)}](+) ([5(H(mu))](+), dppp = Ph(2)PCH(2)CH(2)CH(2)PPh(2)) without internal base.
Wang
Ning
N
State Key Laboratory of Fine Chemicals, DUT-KTH Joint Education and Research Center on Molecular Devices, Dalian University of Technology (DUT), Dalian 116012, China.
Wang
Mei
M
Liu
Jihong
J
Jin
Kun
K
Chen
Lin
L
Sun
Licheng
L
D000588:Amines / Q000737:chemistry*; D002614:Chelating Agents / Q000737:chemistry*; D018360:Crystallography, X-Ray; D005290:Ferric Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D006864:Hydrogenase / Q000737:chemistry* / Q000378:metabolism; D007506:Iron-Sulfur Proteins / Q000737:chemistry* / Q000378:metabolism; D008024:Ligands; D008958:Models, Molecular; D008968:Molecular Conformation; D010720:Phosphines / Q000737:chemistry*; D011522:Protons; D013237:Stereoisomerism
D000588:Amines; D002614:Chelating Agents; D005290:Ferric Compounds; D007506:Iron-Sulfur Proteins; D008024:Ligands; D010720:Phosphines; D011522:Protons; C118830:iron hydrogenase; D006864:Hydrogenase