Toward model complexes of Co-containing nitrile hydratases: synthesis, complete characterization and reactivity toward ligands such as CN- and NO of the first square planar CoIII complex with two different carboxamido nitrogens and two thiolato sulfur donors.
A [CoIII(N2S2)]NEt4 complex, with two carboxamido nitrogens and two alkylthiolato sulfurs, was prepared from N,N'-(2-thioacetylisobutyryl)-2-aminobenzylamine, and characterized. It crystallizes with a distorted square planar structure including two short Co-N bonds (approximately 1.882 A) and two short Co-S bonds (approximately 2.134 A). The ligand defines an 11-atom chelate, which may be Co ligands in the mean plane of Co-containing nitrile hydratase. The CoIII oxidation state, reversibly reduced at -1.13 V (vs. SCE) and irreversibly oxidized at +1.29 V (vs. SCE) in DMF, is stable over a 2 V potential range. From the temperature dependence of its magnetic susceptibility, cobalt(III) was found to be in an S = 1 triplet ground state, in agreement with the broad resonances observed in its 1H-NMR spectrum. Preliminary spectral studies showed that this complex does not interact with imidazole, H2O or HO-, but binds two CN anions or two NO molecules. The IR spectrum of the dinitrosyl complex exhibits two NO stretches at 1765 and 1820 cm(-1), in the range previously observed for dinitrosylated complexes derived from cobalt(I). This result suggests that, similarly to Fe NHases, Co NHases might readily bind NO.
Chatel
S
S
Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, UMR8601, Université René Descartes, Paris, France.
Rat
M
M
Dijols
S
S
Leduc
P
P
Tuchagues
J P
JP
Mansuy
D
D
Artaud
I
I
D003035:Cobalt / Q000737:chemistry* / Q000378:metabolism; D003486:Cyanides / Q000737:chemistry* / Q000378:metabolism; D006836:Hydro-Lyases / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D008024:Ligands; D015394:Molecular Structure; D009569:Nitric Oxide / Q000737:chemistry; D019906:Nuclear Magnetic Resonance, Biomolecular; D011487:Protein Conformation; D013053:Spectrophotometry; D013455:Sulfur / Q000737:chemistry / Q000378:metabolism; D013696:Temperature
D003486:Cyanides; D008024:Ligands; D009569:Nitric Oxide; D003035:Cobalt; D013455:Sulfur; D006836:Hydro-Lyases; C048831:nitrile hydratase