Crystal structure of the dimeric pyridine 1-oxide complex with mercury(I) perchlorate

Abstract

The crystal structure of the title compound, [Hg(C₅H₅NO)₂(ClO₄)]₂ has been determined by single-crystal X-ray diffraction by conventional heavy-atom methods. The structure was refined by a block-diagonal least-squares procedure to R0·10 for 1502 independent visually estimated reflections. Crystals are triclinic, space group P, a= 8·68 ± 0·01, b= 12·76 ± 0·02, c= 14·00 ± 0·02 Å, α= 115·2 ± 0·1, β= 85·8 ± 0·1, γ= 97·5 ± 0·1°, Z= 2 dimers. The mercury(I) species is dimerrc (Hg–Hg 2·523 ± 0·002 Å). The mercury co-ordination does not exhibit the usual two axially co-ordinated ligands; three of the four pyridine 1-oxide molecules bridge adjacent dimers, (Hg–O 2·19–2·77 Å) giving a mercury co-ordination number of 4 or 5. The perchlorate ions are subject to very high thermal motion and are ill-defined. Distances and angles within the pyridine 1-oxide molecules are as expected; the molecular plane does not contain the mercury atom. An improved preparative method for the complex is given.