Spectroscopic Insight into Tetrahedrally Distorted Square Planar Copper(II) Complex: XRD/HSA, Physicochemical, DFT, and Thermal Investigations (original) (raw)
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Inorganic Chemistry, 1996
The tripodal tetramine ligands N(CH 2 CH 2 CH 2 NH 2) 3 (trpn) and N[(CH 2 CH 2 CH 2 NH 2) 2 (CH 2 CH 2 NH 2)] (332) react with Cu(NO 3) 2 ‚3H 2 O in water to give light blue copper(II) complexes. These were characterized by X-ray crystallography to be the square-pyramidal binuclear Cu(II) species [Cu(trpn)(NO 3)] 2 (NO 3) 2 and [Cu(332)(NO 3)] 2-(NO 3) 2 ‚2H 2 O. Selected crystallographic details are as follows, respectively: formula C 18 H 48 Cu 2 N 12 O 12 , C 16 H 48-Cu 2 N 12 O 14 ; M) 751.74, 759.72 Da; both triclinic; both P1 h; a) 8.4346(8), 8.446(4) Å; b) 9.0785(9), 8.744(3) Å; c) 11.9310(12), 12.007(3) Å; R) 94.50(1), 102.68(2)°;) 103.56(1), 94.79(3)°; γ) 117.42(1), 117.69-(4)°; V) 769.7(5), 748.2(13) Å 3 ; both Z) 1; R) 4.16, 4.00; R w) 11.34, 6.74 for 2887 (I g 2σ(I)), 2457 (F o 2 g 3σ(F o 2)) structure factors and 199, 209 refined parameters. The binuclear complex dications exhibit a squarepyramidal coordination geometry around the copper atoms. Three amine functions (one tertiary and two primary) are coordinated to one copper atom and the remaining primary amine arm bridges to the second copper center. Potentiometric and visible spectrophotometric studies show that a protonated square-pyramidal [Cu(HL)(H 2 O) 2 ] 3+ cation (L) trpn, 332, 322 (322) N[(CH 2 CH 2 CH 2 NH 2)(CH 2 CH 2 NH 2) 2 ])) predominates in the intermediate pH region, in contrast to the established trigonal-bipyramidal structure of the tren (tren) tris(2-aminoethyl)amine)) complex of Cu(II). Each [Cu(HL)(H 2 O) 2 ] 3+ has one protonated uncoordinated ligand arm which explains the formation of the binuclear species at neutral pH.
Structure correlation study of four-coordinate copper(I) and (II) complexes
Acta Crystallographica Section B Structural Science, 2000
The geometries of four-coordinate Cu(I) and Cu(II) complexes in the Cambridge Structural Database (CSD) have been analysed systematically and compared using symmetry deformation coordinates and principal component analysis. The observed stereochemistries have been rationalised in terms of the d-electron configurations, interligand repulsion and πbonding effects. The results confirm that the majority of four-coordinate Cu(I) complexes in the CSD adopt tetrahedral geometries, and deviations from tetrahedral symmetry are caused by the presence of chelating ligands or by the incorporation of copper centres into dimeric or polymetallic structures. Four-coordinate Cu(II) complexes generally adopt geometries that are close to square planar; this is particularly evident for bis(chelate) complexes where πbonding is important. Distortions towards tetrahedral geometries are attributable to steric interactions of bulky substituents in the bidentate ligands.
Polyhedron, 2013
In order to investigate the influence of intermolecular hydrogen bonds and the co-ligands [WS 4 ] 2À and Imt on the structures of copper complexes, two new compounds, [WS 4 Cu 3 I(tdmpp)] 4 Á2CH 3 CN (1) and [CuCl(Imt)Á0.5tdmpp] 2 Á2(CH 3) 2 CO (2), have been synthesized in one pot reactions. The reaction of CuI and (NH 4) 2 WS 4 with tdmpp (1,1,3,3-tetrakis(3,5-dimethyl-1-pyrazole)propane) (molar ratio = 3:1:1) in DMF/CH 3 CN (1:4; v/v) led to the formation of complex 1, while treatment of Imt (imidazolidine-2-thione) and CuCl with tdmpp (molar ratio = 2:2:1) in acetone formed complex 2. These complexes have been structurally characterized by X-ray crystallography, infrared spectroscopy and elemental analyses. Thermal analysis and UV-Vis spectroscopic analysis of complex 1 have also been undertaken. Complex 1 has a tetrameric structure which forms intermolecular C-HÁ Á ÁS and C-HÁ Á ÁI hydrogen bonds, resulting in a 2D polymeric structure. In this complex, the copper(I) atoms have two different geometries: trigonal planar (CuS 2 I) and distorted tetrahedral (CuS 2 N 2). In contrast, complex 2 has a dimeric structure in which the copper atoms are four-coordinate with a distorted tetrahedral CuN 2 SCl geometry. The dimeric molecules link to the oxygen atoms of uncoordinated acetone molecules through N-HÁ Á ÁO hydrogen bonds.
European Journal of Inorganic Chemistry, 2010
Bis(N-alkyl-2-oxy-1-naphthaldiminato)copper(II) complexes in the solid state and in N,NЈ-dimethylformamide (DMF) solutions were studied by electronic spectroscopy, X-ray diffraction, DFT calculations, and cyclic voltammetry. The established correlation between the bulkiness of the imine nitrogen substituent, deformation of the copper coordination sphere, and the Cu II /Cu I couple potential in DMF solutions has been re-evaluated, and its inconsistencies explained by using results from DFT calculations and spectroscopic data. According to these DFT calculations, the coordination sphere of the N-ethyl derivative has a flat-tetrahedral geometry. The N-Cu-NЈ and O-Cu-OЈ angles and the dihedral angle between the planes N-Cu-O and NЈ-Cu-OЈ in the solid state
Optical Spectra and …, 2004
[alkyl=ethyl (L2), propyl (L3), and butyl(L4)] ligands have been synthesized and characterized. Analytical data for all three complexes show 1:1 copper-ligand stoichiometry. Wellresolved EPR spectra were recorded in toluene, benzene, and methylene chloride solutions at room temperature and in glassy toluene or toluene-methylene chloride mixtures in the range 20-150 K. The superhyperfine pattern unambiguously demonstrates coordination of two nitrogen atoms to copper; and the spin-Hamiltonian parameters [CuL2, g ʈ =2.115, A ʈ =187¥10 -4 cm -1 ; CuL3, g ʈ =2.128, A ʈ =165¥10 -4 cm -1 ; CuL4, g ʈ =2.138, A ʈ =147¥10 -4 cm -1 ] are as expected for a CuN 2 S 2 coordination core. Quasi-reversible electrochemical behavior was observed in methylene chloride: the Cu(II)/Cu(I) reduction potentials increase from -1.17 V (E°vs Ag/AgNO 3 ) for CuL2 to -0.74 V for CuL4, indicating greater stabilization of Cu(I) in CuL4. Taken together, these data demonstrate that lengthening the N,N¢-alkyl chain distorts the planar CuN 2 S 2 core (CuL2) toward a flattened tetrahedral geometry (CuL4).
IJC-A Vol.60A(04) [April 2021], 2021
The synthesis, spectra, thermal study and crystal structure of a mixed ligand copper(II) compound viz. [Cu(biq)(acac)(NO 3)] 1 (biq = 2,2′-biquinoline, acac = acetylacetonate) are reported. The {CuN 2 O 3 } coordination sphere is made up of two oxygen atoms of an unique acac ligand, an oxygen of the nitrate group and one N atom of biq ligand which form the basal plane {CuNO 3 } of a square pyramid. A second nitrogen atom of the biq ligand occupies the apical position resulting in a distorted square pyramidal {CuN 2 O 3 } polyhedron. In the crystal structure, each neutral square pyramidal copper(II) species is linked with two symmetry related molecules with the aid of intermolecular C−H⋅⋅⋅O hydrogen bonding interactions. A study of fifteen mixed ligand copper(II) acetylacetonates reveals that in this series of compounds, 1 exhibits maximum deviation of the {CuN 2 O 3 } polyhedron from square pyramidal towards trigonal bipyramidal geometry.
Inorganic Chemistry, 1994
The copper(II) complex of the N4S2 encapsulating ligand l-methyl-8-ammonio-3,13-dithia-6,lO,l6,19-tetraazabicyclo-[6.6.6]icosane, [Cu(AMN&sarH)I3+, is reported. Crystals of the complex are monoclinic, of space group P21/a (Z = 4, a = 16.463(3) A, b = 11.073(3) A, c = 17.138(3) A, , 5 = 106.20(1)", R = 0.053 (3449 0). The coordination about the copper(I1) atom is a distorted version of a 4 -t 2 elongated octahedron with the pronounced tetragonal distortion arising from long Cu-N and Cu-S axial bonds of 2.447(5) and 2.600(2) A, respective1 .