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Models for Terminal Ni(S‐Cysteine) Modification in [NiFe]Hydrogenases by Iodoacetamide and Iodoacetate
Author(s) -
Smee Jason J.,
Goodman Dawn C.,
Reibenspies Joseph H.,
Darensbourg Marcetta Y.
Publication year - 1999
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/(sici)1099-0682(199903)1999:3<539::aid-ejic539>3.0.co;2-y
Subject(s) - chemistry , iodoacetamide , hydrogenase , nickel , alkylation , amide , crystallography , cysteine , octahedron , thioether , stoichiometry , stereochemistry , inorganic chemistry , hydrogen , crystal structure , organic chemistry , enzyme , catalysis
The cis ‐dithiolate complex [ N , N′ ‐bis(2‐mercaptoethyl‐2‐methylpropyl)‐1,5‐diazacyclooctane]nickel(II) ( Ni‐1* ) reacts with stoichiometric amounts of iodoacetamide to yield S ‐alkylated, mono‐ and diacetamide complexes, [(AA)Ni‐1*][I] and [(AA) 2 Ni‐1*][I] 2 . Their molecular structures are established by X‐ray crystallography and find the former in pseudo‐square planar geometry with no additional coordination of the amide functionality, while the latter is an octahedral N 2 S 2 O 2 Ni II complex. The assignment of the axial coordination ligands as amide oxygen atoms is consistent with IR‐spectroscopic ν(C=O) results both in the solid and solution states. The complexes are further characterized by UV/Vis spectroscopy, conductance measurements, and electrochemical studies. Comparisons are drawn between the alkylation of these simple dithiolate complexes and the loss of [NiFe]hydrogenase activity upon addition of alkylating agents.