Syntheses, spectroscopic and magnetic properties and X-ray crystal structure of two dinuclear copper(II) compounds with the ligand N3-salicyloyylpyridine-2-carboxamidrazonato

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The crystal structures, spectroscopic and magnetic properties of two dinuclear copper(II) coordination compounds containing the ligand N 3-salicyloylpyridine-2-carboxamidrazonato (abbreviated as spa) are reported. Compound 1, bis[( N 3-salicyloylpyridine-2-carboxamidrazonato- N 1, N 2 O)aquacopper(II)nitrate], [Cu(spa)(H 2O)(No 3)] 2, Cu 2C 26H 26N 10O 12, crystallizes in the triclinic space group P 1, with , a = 8.898(1), b = 12.472(4), c = 14.063(5) A ̊ , α = 91.15(3), β = 97.48(2), γ = 102.25(2)°, V = 1511.8 A ̊ 3 and Z = 2 (dinuclear units). The least-squares refinement based on 3147 reflections, with I>2 σ( I), converged to R = 0.0501 and R w = 0.0581. Two crystallographic independent five-coordinated copper(II) atoms are present in this structure, which differ slightly in bond distances and angles. Both metal ions are in a squares pyramidal environment of which the basal plane is formed by two nitrogen and an oxygen donor atom of the spa ligand and a water molecule. A nitrate anion occupies the apical position. The mononuclear fragments of symmetry related metal ions are linked in dinuclear units via a four-fold hydrogen bonding network, with Cu1Cu 1′ (1-x,1 −y, 1-z)=4.723(2) A ̊ and Cu 2 Cu2″ (−x, −y, −z)=4.616(2) A ̊ . Compound 2, bis[( N 3-salicyloylpyridine-2-carboxamidrazonato- N 1, N 2, O)diaquacopper(II)]diperchlorate, [Cu(spa)(H 2O) 2] 2(ClO 4) 2, Cu 2C 26H 30N 8O 16Cl 2, crystallizes in the triclinic space group P 1 , with a = 7.138(1), b = 10.655(2), c = 12.844(1) A ̊ , α = 103.71(1), β = 98.43(1), γ = 102.19(2)°, V = 907.4 A ̊ and Z = 1 (dinuclear unit). The least-squares refinement based on 3022 reflections, with P>2 σ( I), converged to R = 0.0359 and R w = 0.0475. The copper(II) ion is in a distorted octahedron, with two N and an O donor atom of the spa ligand and a water molecule in the equatorial plane. An additional water molecule and a phenol-O are in the axial positions. There is an intramolecular stacking of two [Cu(spa)(H 2O) 2] units, with CuCu′ (1-x, −y, −z)=6.2810(7) A ̊ . The X-band powder EPR spectra for [Cu(spa)(H 2O)(NO 3)] 2 show the usual spectrum for copper(II) ions in an axial symmetry. For [Cu(spa)(H 2O) 2] 2(ClO 4) 2 the signals at g = 4.04, 3.02, 2.08 and 1.66, give evidence for Cu … Cu exchange splittings, although the magnetic interaction is extremely weak and could not be detected by magnetic susceptibility measurements over the temperature range 10–280 K.