Nickel-iron dithiolato hydrides relevant to the [NiFe]-hydrogenase active site.
The ferrous dithiolato carbonyl Fe(S(2)C(3)H(6))(CO)(2)(dppe) (1) condenses with NiCl(2)(dppe) to give [FeNi(pdt)(mu-Cl)(CO)(dppe)(2)]BF(4) ([2Cl](+)). The corresponding reaction of the ditosylate Ni(OTs)(2)(dppe) gave the dication [(CO)(2)(dppe)Fe(pdt)Ni(dppe)](OTs)(2) ([2(CO)](OTs)(2)) (pdt = 1,3-propanedithiolate; dppe = 1,2-C(2)H(4)(PPh(2))(2); OTs(-) = CH(3)C(6)H(4)-4-SO(3)(-)). Reduction of the bimetallic dicarbonyl with borohydride salts afforded impure, thermally stable hydride, [(CO)(dppe)Fe(pdt)(mu-H)Ni(dppe)](+) ([2H](+)). A reliable route to NiFe(SR)(2)H species entailed protonation of (CO)(3)Fe(pdt)Ni(dppe) to give [(CO)(3)Fe(pdt)(mu-H)Ni(dppe)](+) ([3H](+)). The iron-nickel dithiolato hydride, [3H]BF(4), was characterized crystallographically: as anticipated by biophysical studies, the hydride ligand is bridging, the Fe center is octahedral, and the Ni center is pentacoordinate. Solutions of [3H]BF(4) undergo substitution by dppe to give [2H](+). The hydride undergoes rapid deprotonation and is an electrocatalyst for hydrogen evolution from trifluoroacetic acid. Oxidation of 3 gives a mixed valence species [3](+), a potential model for the Ni-L state.
School of Chemical Sciences, University of Illinois, Urbana, Illinois 61801, USA.
Bryan E
BE
Barton
C Matthew
CM
Whaley
Thomas B
TB
Rauchfuss
Danielle L
DL
Gray
D020134:Catalytic Domain; D006864:Hydrogenase / Q000737:chemistry* / Q000378:metabolism; D058085:Iron Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D008958:Models, Molecular; D009532:Nickel / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D009943:Organophosphorus Compounds / Q000737:chemistry*; D013438:Sulfhydryl Compounds / Q000138:chemical synthesis / Q000737:chemistry*
D058085:Iron Compounds; D009942:Organometallic Compounds; D009943:Organophosphorus Compounds; D013438:Sulfhydryl Compounds; C049078:bis(diphenylphosphine)ethane; D009532:Nickel; C043296:nickel-iron hydrogenase; D006864:Hydrogenase