Crystal structures of bis(acetylacetonato-µ-allyl-platinum), [Pt(C3H5)(C5H7O2)]2, and bis-[di-µ-allyl-(di-µ-chloro-diplatinum)], [Pt(C3H5)Cl]4

Abstract

The X-ray crystal structures of the title compounds have been determined from photographic data. The acetylacetonato-complex (I) is dimeric, with approximate C₂ symmetry, and crystallises in the monoclinic space-group P2₁/c with Z= 4 in a unit cell of dimensions: a= 10·01 ± 0·01, b= 10·00 ± 0·01, c= 17·29 ± 0·03 Å, β= 100·2°± 0·2°. The chloro-complex (II) exists as a tetramer of approximate D₂ symmetry, and crystallises in the triclinic space-group P, with Z= 4 in a unit cell of dimensions: a= 13·34 ± 0·03, b= 16·16 ± 0·03, c= 8·33 ± 0·01 Å, α= 90·2 ± 0·2, β= 100·2 ± 0·2, γ= 93·2°± 0·2°. Both structures were solved by conventional Patterson and Fourier methods and refined by least-squares techniques to R 11·3%[(I); 1948 independent reflections] and 12·0%[(II); 2975 independent reflections].

In (I) each allyl group of the Pt ⋯ Pt bridge is σ-bonded to one platinum and π-bonded to the other. Similarly diallyl bridges occur in (II) where non-planar dichloro-bridges alternate with the diallyl bridges in the ring. The Pt–O bond lengths in (I) and Pt–Cl bond lengths in (II) reflect the differing trans-influences of the σ- and π- bonded allyl group.