X-Ray molecular structure of cyclo-bis-(µ-acetato-µ-nitrosyl)-bis[di-µ-acetato-diplatinum(II)]; a tetranuclear complex containing both nitrosyl and acetate bridges

Abstract

The crystal structure of the title complex, in the form of an acetic acid solvate Pt₄(AcO)₆(NO)₂,2AcOH, has been determined from three-dimensional X-ray diffractometer data. Crystals are monoclinic with unit-cell dimensions a= 23·724(3), b= 8·682(1), c= 14·195(2)Å;, β= 92·98(1)°; space group C2/c, Z= 4. Full-matrix least-squares refinement, by use of 1521 independent reflections, has reached R 0·066.

The complex molecule, which lies around a diad axis, is tetranuclear with the four platinum atoms forming an approximate rectangle of sides 2·944 and 3·311 Å. Each of the two independent metal atoms is bonded to three oxygen atoms from bridging acetate groups and to one nitrogen atom from a bridging nitrosyl group, to give a square-planar co-ordination. The mean Pt–N (1·91 Å) and N–O distances (1·22 Å), and the sp² geometry at the bridging nitrogen atom are all consistent with the formulation of the nitrosyl group as NO^–. The Pt–O distances are unexceptional, mean 2·04 Å. Some Pt ⋯ Pt distances and the stacking of the molecules suggest that weak metal–metal interactions exist. The solvated acetic acid occurs as isolated hydrogen-bonded pairs of molecules.