The crystal structure of bis-(3-methylpentane-2,4-dionato)copper(II)

Abstract

A three-dimensional X-ray crystal structure analysis has been carried out on the copper complex of 3-methyl-acetylacetone. All measurements were made at 180°K. There is one molecule in a triclinic unit cell having a= 8·036, b= 4·81, c= 9·086 Å, α= 88·2°, β= 108·9°, γ= 73·6°, and space group P. The copper atom lies on the centre of symmetry at the origin. The carbon and oxygen atoms were located in Patterson projections; after the parameters, including anisotropic vibration, of these atoms had been refined by least squares, the hydrogen atoms were located in a three-dimensional difference Fourier synthesis. Refinement was continued until R was 0·091. In each ligand the six carbon and two oxygen atoms are coplanar, and the copper atom is only 0·02 Å from this plane, so the whole molecule (apart from hydrogen atoms) approximates to mmm symmetry. The average bond lengths, corrected for rotational oscillation, are Cu–O = 1·908 ± 0·004 Å, C–O = 1·285 ± 0·009 Å, C–C (ring)= 1·409 ± 0·009 Å, C–C (methyl)= 1·499 ± 0·01 Å, with C–H ranging from 0·8 to 1·2 ± 0·1 Å. The bond angles are O–Cu–O 92·6 ± 0·2°, Cu–O–C 127·0°, O–C–C (ring) 125·5°, C–C–C (all in ring) 122·1°, O–C–C (methyl) 113·8°, C–C–C (terminal methyl) 120·8°, and C–C–C (3-methyl) 119·1° all ±33′. The copper atom is 4-co-ordinated, its nearest neighbours in the “fifth” and “sixth” positions being the γ-carbon atoms, C(3), of other molecules at a distance of 3·216 ± 0·007 Å.