Fluxional chromophores of bis(di-2-pyridylamine)nitritocopper(II) cations: crystal structures and electronic properties of the complexes bis(di-2-pyridylamine)nitritocopper(II) nitrate and bis(di-2-pyridylamine)nitritocopper(II) perchlorate

• Published in: Inorganica Chimica Acta Vol. 335; pp. 36 - 42
• Main Authors: Youngme, Sujittra, Chaichit, Narongsak, Koonsaeng, Nuttamon
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 27.06.2002
• Subjects: cis-Distorted octahedron; Copper complexes; Di-2-pyridylamine; Fluxional behaviour; Nitrito complexes; Plasticity effect; Di-2-pyridylamine; Nitrito complexes; cis-Distorted octahedron; Fluxional behaviour; Plasticity effect; Copper complexes
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/S0020-1693(02)00758-2

The X-ray crystal structures of two cation-distortion isomers of [Cu(dpyam) 2(ONO)](NO 3) ( 1) and [Cu(dpyam) 2(ONO)](ClO 4) ( 2) complexes are reported and shown to contain an asymmetric cis-distorted CuN 4O 2 chromophore. In 1 the copper atom and the asymmetrically bonded nitrito group lie on a crystallographic C 2 axis. The nitrito group is clearly disordered about the C 2 axis giving a square pyramidal cis-distorted octahedral (4+1+1*) chromophore rather than a pseudo regular cis-distorted octahedral chromphore. In 2 a distortion of the CuN 4O 2 chromophore towards a square pyramidal (4+1+1*) geometry is also present, but with well-ordered and less asymmetric nitrito group. The polycrystalline ESR spectra of 1 and 2 are temperature independent suggesting that both complexes appear to be near the static distortion limit of the fluxional CuN 4O 2 chromophore geometry. The electronic reflectance spectra of 1 and 2 involve two bands at approximately 14 700 and 9800 cm −1 for 1, and approximately 14 970 and 10 000 cm −1 for 2 and relate to the underlying static CuN 4O 2 (4+1+1*) chromophore geometry. The X-ray crystal structures of two cation-distortion isomers of [Cu(dpyam) 2(ONO)](NO 3) ( 1) and [Cu(dpyam) 2(ONO)](ClO 4) ( 2) complexes are reported and shown to contain an asymmetric cis-distorted CuN 4O 2 chromophore. In 1 the copper atom and the asymmetrically bonded nitrito group lie on a crystallographic C 2 axis. The nitrito group is clearly disordered about the C 2 axis giving a square pyramidal cis-distorted octahedral (4+1+1*) chromophore rather than a pseudo regular cis-distorted octahedral chromphore. In 2 a distortion of the CuN 4O 2 chromophore towards a square pyramidal (4+1+1*) geometry is also present, but with well-ordered and less asymmetric nitrito group.