- Role of Halide Ions in the Nature of the Magnetic Anisotropy in Tetrahedral CoII Complexes
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A series of mononuclear tetrahedral CoII complexes with a general molecular formula [CoL2X2] [L=thiourea and X=Cl (1), Br (2) and I (3)] were synthesized and their structures were characterized by single-crystal X-ray diffraction. Direct-current (dc) magnetic susceptibility [χMT(T) and M(H)] and its slow relaxation of magnetization were measured for all three complexes. The experimental dc magnetic data are excellently reproduced by fitting both χMT(T) and M(H) simultaneously with the parameters D=+10.8 cm?1, g1=2.2, g2=2.2, and g3=2.4 for 1; D=?18.7 cm?1, giso=2.21 for 2; and D=?19.3 cm?1, giso=2.3 for 3. The replacement of chloride in 1 by bromide or iodide (in 2 and 3, respectively) was accompanied by a change in both sign and magnitude of the magnetic anisotropy D. Field-induced out-of-phase susceptibility signals observed in 10 % diluted samples of 1–3 imply slow relaxation of magnetization of molecular origin. To better understand the magnetization relaxation dynamics of complexes 1–3, detailed ab initio CASSCF/NEVPT2 calculations were performed. The computed spin Hamiltonian parameters are in good agreement with experimental data. In particular, the calculations unveil the role of halide ions in switching the sign of D on moving from Cl? to I?. The large spin–orbit coupling constant associated with the heavier halide ion and weaker π donation reduces the ground state–excited state gap, which leads to a larger contribution to negative D for complex 3 compared to complex 1. Further magnetostructural D correlations were developed to understand the role of structural distortion in the sign and magnitude of D values in this family of complexes.
- Vaidya, Shefali,Singh, Saurabh Kumar,Shukla, Pragya,Ansari, Kamaluddin,Rajaraman, Gopalan,Shanmugam, Maheswaran
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- Nucleation studies of ZTC doped with l-arginine in supersaturated aqueous solutions
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The metastable zonewidth studies are carried out for various temperatures for supersaturated aqueous solutions of zinc thiourea chloride added with 1 mole % of l-arginine. The metastable zonewidth is increased with the addition of l-arginine. The inductio
- Balu,Rajasekaran,Murugakoothan
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- Growth and characterization of Fe3+-doped bis(thiourea)zinc(II) chloride crystals
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Fe3+-doping at ~10 mol% in aqueous medium during crystal growth by slow evaporation solution method in bis(thiourea)zinc(II) chloride (BTZC) leads to form a new compound C2H8Cl 2N4S2Zn
- Nithya,Karthikeyan,Ramasamy,Muthu,Meenakshisundaram
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- Thiourea complexes in synthesis of Cd1-x ZnxS solid solutions
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Solid solutions of the CdS-ZnS system deposited as polycrystalline films by aerosol pyrolysis from aqueous solutions of cadmium and zinc thiourea complexes have been studied. The phase composition and solid-phase solubility are dictated by the nature of i
- Naumov,Samofalova,Semenov,Nechaev
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- Crystal growth and vibrational spectroscopic studies of the semiorganic non-linear optical crystal - Bisthiourea zinc chloride
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The semiorganic non-linear optical crystal bisthiourea zinc chloride (BTZC) was grown by mixed solvent slow evaporation technique. The solubilities under various solvents in different proportions have been studied. Vibrational spectra were recorded to det
- Krishnakumar,Nagalakshmi
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- Systematic FT-Raman spectroscopic study of twelve bis-thiourea complexes, A(tu)2B2 (A = Zn, Cd, Hg; B = Cl, Br, I, SCN)
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This work undertakes a systematic FT-Raman study of twelve thiourea complexes with stoichiometries A(tu)2B2 (A = Zn, Cd, Hg; B = Cl, Br, I, SCN). With the exception of Cd(tu)2Cl2, the Raman spectra are reported here for the first time. The main modifications observed in the vibrational dynamics of the organic ligand are basically due to the coordination with the cation, with the influence of the anion less clear. These modifications show an increase with the softness of the metallic ion. The statistical analysis of the band wavenumber data shows that the ligand/cation interactions are stronger than the corresponding cation-anion bonds. This could explain the thermal behaviour of these complexes, which decompose easily at moderately high temperatures (600-700 K), producing the corresponding sulfides. The coordination of the thiocyanate anion in their complexes is accomplished via the sulfur atom (Hg2+ complex) or via the nitrogen atom (Zn2+ and Cd2+ complexes), although in both cases the association is largely ionic.
- Alia,Edwards,Stoev
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