A multinuclear (1H, 13C, 113Cd) nuclear magnetic resonance and magnetic circular dichroism spectroscopic study of thiolate complexes of cadmium (original) (raw)
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Journal of Coordination Chemistry
Cadmium(II) complexes of thiones and thiocyanate, [(>C=S)2Cd(SCN)2], have been prepared and characterized by IR and NMR spectroscopy. An upfield shift in the >C=S resonance of thiones in the C NMR and downfield shift in N–H resonance in H NMR are consistent with sulfur coordination to cadmium(II). The presence of ν(N–H) of thiones in IR spectra of the complexes indicates the thione forms of the ligands in the solid state; some contribution of the thiolate form was observed in one complex. The appearance of a band around 2100 cm in IR and a resonance around 132 ppm in C NMR indicates the binding of thiocyanate to cadmium(II).
Bis(mercaptoimidazolyl)borates and the control of nuclearity in cadmium thiolate complexes
Polyhedron, 2003
Bis(mercaptoimidazolyl)borate cadmium(II) thiolate complexes of empirical formula (Bm Me )CdSR (R ¼ Ph, p-Tol, C 6 F 5 ) have been readily prepared from the new bromo derivative (Bm Me )CdBr and the corresponding thallium(I) thiolates Tl(SR). The new complexes have been characterized analytically and spectroscopically and, in the case of the para-thiocresolate derivative (Bm Me )CdS-p-C 6 H 4 Me, by X-ray diffraction. While the closely related tris(mercaptoimidazolyl)borate cadmium phenylthiolate complex (Tm p-Tol )CdSPh is mononuclear, (Bm Me )CdS-p-C 6 H 4 Me exhibits in the solid state a dimeric structure in which each fivecoordinate cadmium atom displays a trigonal bipyramidal geometry.
The Journal of Physical Chemistry, 1995
Formation processes of CdS ultrasmall particles from cadmium complexes of 2-mercaptoethanol (RSH) were investigated by means of stopped-flow and NMR spectroscopies. Two different initial processes depending on the amount of RSions have been found. The presence of S&dlo(SR)12 clusters in solution was observed by NMR spectroscopy. Formation of [S4Cdl7(SR)24I2+ clusters having a 290-nm absorption peak was suggested. The correlation between the absorption peak and the diameter for polynuclear Cd2+-SR-complexes is expressed with the finite-depth quantum well model for ultrasmall particles. Electronic interaction between the capping agent and particle framework was suggested on the basis of the differences observed in the absorption wavelengths of the CdS-RSH clusters and the corresponding CdS-thiophenol clusters. Ultrasmall semiconductor particles whose diameters are a few nanometers have been paid special attention because of their unique size-dependent properties, such as optical and physicochemical proper tie^.'-^ These properties are affected not only
Russian Journal of Coordination Chemistry
Two mercury(II) cyanide complexes of N-ethylthiourea (Ettu) and N-propylthiourea (Prtu) ligands, [Hg(Ettu) 2 (CN) 2 ] (1) and [Hg(Prtu) 2 (CN) 2 ] (2), were prepared and their crystal structures were determined by X-ray crystallography. In both structures, the mercury atom is coordinated to two sulfur atoms of thioureas and two cyanide carbon atoms in a pseudo-tetrahedral mode with the bond angles in the range of 90.52(11)-162.2(3)°. The structures are stabilized by N-H---S, N-H---N, and C-H---N intramolecular and intermolecular hydrogen bonds. Crystallographic reports about mercury(II) complexes containing thioamides establish that these ligands are coordinated via the sulfur atom [1-26]. The crystal structures of the 1:2 complexes usually consist of discrete monomeric molecules [1-20], while those of 1:1 often involve dimeric species [20-26]. However, in both types of complexes, mercury(II) exhibits a tetrahedral or pseudo-tetrahedral coordination environment. We have recently reported the crystal structures of Hg(CN) 2 complexes of methylthiourea (Metu) [7], N,N′-diethylthiourea (Dintu) [8], N,N′-dibutylthiourea (Dbtu) [9], and tetramethylthiourea (Tmtu) [27]. Although the structures of other thiourea complexes are usually of the type L 2 HgX 2 [7-9], the Tmtu complex, [{(tetramethylthiourea) 2 Hg(CN) 2 } 2 ⋅Hg(CN) 2 ] is trinuclear consisting of two independent [(Tmtu) 2 Hg(CN) 2 ] moieties bridged by a Hg(CN) 2 unit [27]. In order to investigate further about the structures of mercury cyanide complexes, we report here the crystal structures of two monomeric Hg(CN) 2 complexes: bis(cyanido)bis(Nethylthiourea-κS)mercury(II), [Hg(Ettu) 2 (CN) 2 ] (1) and bis(cyanido)bis(N-propylthiourea-κS)mercury(II), [Hg(Prtu) 2 (CN) 2 ]
Cadmium-113 NMR studies of small dynamically stable cadmium(2+) complexes
Inorganic Chemistry, 1985
13Cd and I3C N M R spectra have been obtained on several dynamically stable cadmium complexes. In several cases a "C-Il'Cd three-bond coupling has been observed and utilized in the assignment of the I3C N M R spectra. The pH dependence of the l13Cd resonance from the cadmium-ethylenediamine-N,N,"'-tetraphosphonate complex shows that this complex has two acid dissociation constants, pK, = 7.85 and 8.80, respectively. 13Cd nuclear Overhauser effect, NOE, =1 + q, and spin lattice relaxation time, T I , were determined on all the complexes and used in the analysis of the contribution to the relaxation mechanism from the dipolar interaction with protons and chemical shift anisotropy. Together, the multinuclear N M R parameters contribute to a detailed understanding of the structure and dynamics of these metal complexes. Furthermore, the Il3Cd N M R parameters from these model complexes provide important new data relevant to the interpretation of the lI3Cd N M R parameters from biological systems.
Cadmium cyanide complexes with heterocyclic thiones: Solid state and solution NMR studies
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2009
a b s t r a c t Cadmium(II)cyanide complexes of various thiones (imidazolidine-2-thione, diazinane-2-thione and their derivatives) have been prepared and characterized by elemental analysis, IR and solid as well as solution NMR spectroscopy. It appears from the IR data that all complexes are non-ionic [(>C S) 2 Cd(CN) 2 ]. An upfield shift in the 13 C NMR and downfield shifts in the 1 H NMR are consistent with the sulfur coordination to cadmium(II). The solid 113 Cd NMR data show the presence of different coordination numbers in some complexes. .sa (A.A. Isab), miwazeer@kfupm.edu.sa (M.I.M. Wazeer).
Polyhedron, 2003
A series of cadmium(II) complexes with N -alkyl or aryl and N ,N ?-dialkyl or diaryl thioureas (RNHCSNHR?; where R 0/R?0/ CH 3 , CH 2 CH 3 , C 6 H 5 and or R?0/H) have been synthesised and characterised. The structures of the polymer [CdCl 2 (CS(NH 2 )NHCH 3 ) 2 ] n (I) and monomer [CdCl 2 (CS(NH 2 )NHCH 2 CH) 2 ] (II) were determined by single crystal X-ray methods. The structure (I) is a polymer chain built from [CdCl 3 S 3 ] distorted octahedra. Complex II is monomeric with a distorted tetrahedral geometry at the cadmium centre. 1 H NMR spectroscopy in deuterated dimethyl sulfoxide at room temperature had broadened NH peaks in the lower field (region 6.0 Á/10.0 ppm) which indicates the presence of both cis and trans -isomers for the Nalkylthioureas. All the spectroscopic data obtained are consistent with the coordination of ligands by sulphur atom to the metal ion. Thermogravimetric studies show that several of these complexes decompose cleanly to CdS and may be useful in materials preparation. #
Spectroscopy, 2011
Cadmium and mercury selenocyanate complexes of 2-thiouracil (TU) and 2,4-dithiouracil (DTU) ligands have been synthesized to form complexes of the type [M(SeCN) 2 (TU)] and [M(SeCN) 2 (DTU)] (where M is Cd 2+ or Hg 2+ ) and studied by various spectroscopic techniques such as IR, 1 H and 13 C NMR in solution and in the solid state for 13 C, 15 N, and 113 Cd nuclei. Based on IR, and solution and solid-state 13 C NMR data, stronger cadmium bonding to the thiouracil was observed compared to that of mercury. Anti-bacterial activities of these complexes have been investigated with standard type culture of Escherichia coli (MTCC 443), Klebsiella pneumoniae (MTCC 109), Pseudomonas aeruginosa (MTCC 1688), Salmonella typhi (MTCC 733) and Staphylococcus aureus (MTCC 737) and show that ligands exhibit more anti-bacterial activities than that of the corresponding Cd(II) and Hg(II) complexes.