The cyanamido-nitrate ligand has potentially four donor atoms: N(amide), N(nitrile) and two O atoms. The variety of coordination opportunities for cyanamidonitrate ligand (monodentate, or bidentate bridging ligand), in dependence on the kind of the central atom, especially on its hardness is expected.New cyanamidonitrate complex of composition [Cu(NO2NCN)2(dmpz)3] (where (dmpz) = 3,5-dimethylpyrazole) was prepared and the crystal structure solved. The crystal structure is built from discrete [Cu(NO2NCN)2(dmpz)3] units. The central Cu(II) atom is found to be in the tetragonal-pyramid coordination. In equatorial plane there are three 3,5-dimethylpyrazole molecules and one cyanamidonitrate anion coordinated by nitrile nitrogen atom. The axial position is completed by nitrile nitrogen atom from another cyanamidonitrate anion. Interatomic distances are compared and discussed with others solved crystal structures: Heteroaromatic n-oxides are unique compounds due to n-o group which can serve either as electronoacceptor or as electronodonor, that depends on compound structure [1]. Their complexes and salts have broad spectrum of biological activities: some of them are used as medical remedies and plant growth activators. X-ray powder diffraction patterns were obtained on two high-resolution powder diffractometers: Guinier de Wolff camera and X'pert diffractometer (Cu-Kalpha1 radiation). Unit cell dimensions were determined with the program TREOR [2]. The structures of the title compounds were determined by the MRIA program [3] using grid search [4] and simulated annealing [5] techniques. The subsequent bond-restrained Rietveld refinement gave bond lengths and angles within the expected ranges. Crystal data of Bis(2-methylquinoline N-oxide) zinc chloride(II): The unit cell is orthorhombic, Pbcn; a = 14.048(6), b = 10.192(5), c = 14.051(6) Å; Z = 4; Mr = 454.46. Bragg R-factor Rb = 10.7, profile factor Rp = 7.1. Crystal data of Bis(quinoline N-oxide)copper(II) chloride: The unit cell is monoclinic, P21/n; a = 11.780(3), b = 14.872(5), c = 6.061(2) Å, β = 98.27(2)°.; Z = 4; Mr = 279.51. Bragg R-factor Rb = 7.9, profile factor Rp = 5.4. Space group was assumed during the structure determination. Profile function: split-type pseudo-Voigt. , R(all data) = 0.0825, wR2 = 0.1718, Asymmetric unit contains two molecules of complex which did not show significant differences in the geometrical parameters. Ligands are coordinated in the fac fashion through the three 'pyridine' nitrogen placed in the equatorial plane, while the remaining positions are occupied by the amino nitrogens.The coordination geometry can be described as deformed octahedral. In the coordination polyhedron the shortest bonds are formed between the Co and two axial amino nitrogens (1.895/1.892 Å) while the longest bond are between the Co and pyridine nitrogen trans to amino nitrogen (1.950/1.945 Å). Angle formed by the trans pyridine nitrogens is 168.2/168.8°, with the dihedral angle between the pyrazole mean planes of 78°. Molecules are mutually connected by the...
C 30 H 48 Cl 2 N 14 Ni 2 O 2 S 6 , monoclinic, P12 1 /c1 (no. 14), a = 12.0407(7) Å, b = 11.8861(6) Å, c = 15.7389(9) Å, b = 93.904(1)°, V = 2247.3 Å 3 , Z = 2, Rgt(F) = 0.032, wR ref (F 2 ) = 0.069, T = 120 K. Source of materialThe complex was synthesized by mixing hot ethanolic solution of the ligand 3,5-dimethyl-1-thiocarboxamide pyrazole (Pz-CS, 1 mmol) and NiCl 2 · 6H 2 O (0.5 mmol). DiscussionAs a part of systematic study on complexing properties of pyrazolyl molecules [1][2][3], the present paper reports on a new Ni(II) complex.The crystal structure of the ligand 3,5-dimethyl-1-thiocarboxamide pyrazole (L1) was recently reported [4] and a DFT computation has been used to obtain in-vacuo theoretical geometry [5].The interesting aspect of this ligand and its derivative is its ambidentate nature. It can coordinate bidentately to metal through the pyrazole ring nitrogen and thiolato sulfur or by using ring nitrogen and iminyl nitrogen (of thiocarbamyl group). Explanation of the ambidentate nature of this ligand in terms of the HSAB model [6] implies its capability to stabilize different oxidation state of the same metal. It could be also expected that oxidation state of the ligand would influence the mode of coordination. It was found that in the case of Co(III)(L) 3 complex [7], monodeprotonated L1 is bound to metal through the pyrazole ring nitrogen and the thiocarboxamide nitrogen. However, in the Co2L2Cl4 fivecoordinated Co (II) is bound to neutral L1, through the pyrazole nitrogen and thiol sulfur. In accordance with the HSAB model [8], it is expected that ligand L1 will bind to Ni(II) through the pyrazole nitrogen and sulfur from the thiocarboxamide fragment. This mode of coordination was observed in the Ni(II) complex with the closely related monodeprotonated ligand 3,5-dimethyl-1-(N-ethyl)-thiocarbamylpyrazole (L2) [9]. In contrast to this, recent X-ray powder diffraction study [10] revealed that monodeprotonated ligand L1 is bound to Ni(II) through the nitrogen atoms of the pyrazole ring and the thiocarboxamide group. This observation is not in accordance with the expectations based on HSAB model, which stress the importance of obtaining more information on the factors important for complexing properties of this ligand. The crystal structure of the title compound is built up of discrete centrosymmetric dinuclear units, with end-to-end bridging NCS anionic ligands, Cl anions, and ethanol molecules. Two neutral molecules of L1 coordinate to Ni(II) through the pyrazole-ring N atoms and thiocarboxamide S atoms, which is in accordance with the HSAB model. The Ni(II) adopts distorted octahedral coordination, with thiocyanato N, and thiol S placed in the axial positions. Two pyrazolyl ligands show similar arrangement, except for the torsion angle NNCS (ÐN10N8C16S2 = 14.66°, ÐN12N9C18S5 = 32.44°), which indicates significant difference in the conformation of two chelate rings. Greater distortion of the chelate ring is associated with the longer axial NiS bond (d(Ni1S5) = 2.519 Å, d(Ni1S2) = 2.422 ...
C 27 H 27 Cl 2 N 9 Zn, tetragonal, P42 1 c (no. 114), a =17.522(2) Å, c =18.583(3) Å, V =5705.4 Å 3 , Z =8,R gt (F) =0.040, wR ref (F 2 ) =0.114, T =293 K. Source of materialAm ixture of 3-amino-5-phenylpyrazole (0.16 g, 1m mol) and ZnCl 2 (0.08 g, 0.5mmol) was dissolved under heating in ethanol (4 ml). Afterthree days thecolourless crystals were obtained. Experimental detailsAllHatoms were included in calculated positions andtreated as riding with DiscussionThe complexing properties of pyrazole derivatives have been the subject of extensiver esearch [1,2].
Page s 275 electron density in terms of multipole model are derived to investigate the electron density distribution and chemical bonds. All chemical bonds will be characterized based on atoms in molecule theory, and classified by the location of the bond critical point (BCP) and its associated topological properties. The XAS of Mo K-edge is used to characterize the electronic states of both complexes and the light induced transformation of complex 2. All experimental observations will be compared with the density functional theory calculation. The different chemical reaction properties between 1 and 2 will be rationalized based on all experimental and theoretical results.
MS15 P10 Crystal structure of Hexa-µ 2-chloro-µ 4-oxo-tetrakis-(3,5-dimethylpyrazole)copper(II) Željko K.
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