title: Spectroscopic, electrochemical, and alkylation reactions: tert-butyl N-(2-mercaptoethyl)carbamate copper(II) and nickel(II) complexes as structural mimics for the active site of thiolate-alkylating enzymes.
abstract: Two new dithiolate copper(II) and nickel(II) complexes with the ligand tert-butyl N-(2-mercaptoethyl)-carbamate (Boc-SH) were prepared. Their structures were established to be [(Boc-S)2M], where M=Cu (1) and Ni (2) by using elemental analysis, thermal analysis, molar conductivity, FT-IR, Raman, UV/VIS, and ESR as well as EI-mass spectroscopic methods. The X-ray structure of the ligand Boc-SH was also determined. Spectral data showed that the carbamate ligand act as anioinic bidentate through one immine nitrogen and one thiolate sulfur donor atoms. The spectral techniques suggest that both complexes appear to have square planar geometries. The very low electrical conductance of the two complexes supports their neutral nature. The redox behaviors of the obtained complexes were also investigated by cyclic voltammetry. The monomeric nature of both complexes was assessed from their magnetic susceptibility values. The thermoanalytical data evidence that complex (2) is stable up to 165°C and undergo complete decomposition, resulting in NiO as a residual product. The TEM image of the obtained oxide residue showed its nanosize cluster, suggesting that complex (2) may be used as a precursor for the formation of nanooxide. The methylation reactions of the two dithiolate complexes (1) and (2) with methyl iodide appear to occur intramolecularly at the metal(II)-bound dithiolates, forming the metal(II)-bound dithioether complexes [M(Boc-SCH3)2]I2 with clean second-order constants of 7.95×10(-2) and 10.59×10(-2) M(-1) s(-1), respectively.
authors.affiliation: Department of Chemistry, Faculty of Science, Taif University, Taif, Saudi Arabia; Department of Chemistry, Faculty of Science, Kafr El-Sheikh University, Egypt. Electronic address: ibrahim652001@yahoo.com.
authors.forename: Mohamed M
authors.initials: MM
authors.lastname: Ibrahim
authors.affiliation: Department of Chemistry, Faculty of Science, Taif University, Taif, Saudi Arabia; Department of Chemistry, Faculty of Science, South Valley University, Qena, Egypt.
authors.forename: Gaber A M
authors.initials: GA
authors.lastname: Mersal
authors.affiliation: Department of Chemistry, Faculty of Science, Kafr El-Sheikh University, Egypt.
authors.forename: Nagi
authors.initials: N
authors.lastname: El-Shafai
authors.affiliation: Department of Chemistry, Faculty of Science, Kafr El-Sheikh University, Egypt.
authors.forename: Abdel-Motaleb M
authors.initials: AM
authors.lastname: Ramadan
authors.affiliation: Department of Chemistry, Faculty of Science, Taif University, Taif, Saudi Arabia; Department of Chemistry, Faculty of Science, Cairo University, Egypt.
authors.forename: Mohamed M
authors.initials: MM
authors.lastname: Youssef
mesh_terms: D000478:Alkylation; D055162:Biocatalysis; D040761:Biomimetic Materials / Q000737:chemistry*; D002219:Carbamates / Q000737:chemistry*; D020134:Catalytic Domain; D056831:Coordination Complexes / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray; D055664:Electrochemical Techniques; D004926:Escherichia coli / Q000201:enzymology; D029968:Escherichia coli Proteins / Q000737:chemistry; D008745:Methylation; D009532:Nickel / Q000737:chemistry*; D019853:O(6)-Methylguanine-DNA Methyltransferase / Q000737:chemistry; D010084:Oxidation-Reduction; D013055:Spectrophotometry, Infrared; D013059:Spectrum Analysis, Raman; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D014157:Transcription Factors / Q000737:chemistry
chemical_list: D002219:Carbamates; D056831:Coordination Complexes; D029968:Escherichia coli Proteins; D013438:Sulfhydryl Compounds; D014157:Transcription Factors; D003300:Copper; D009532:Nickel; C045675:Ada protein, E coli; D019853:O(6)-Methylguanine-DNA Methyltransferase
keywords: Biomimetic; Electrochemical; Spectroscopic; Thiolate alkylating enzymes; Transition metal(II)-bound dithiolate complexes; X-ray crystallography