Some mercury halide–cobalt and –rhodium compounds

Abstract

Reaction of mercuric chloride or bromide with Co(CO)2(π-C5H5) gives the complexes Co(CO)2(π-C5H5)·nHgX2(n= 1 or 2; X = Cl or Br). Mercuric iodide gives only a 1 : 1 adduct. In the 1 : 1 adducts the Co(CO)2(π-C5H5) acts as a Lewis base and the complexes are probably composed of Co(CO)2(π-C5H5)HgX+ and X– ions linked together by mercury–halogen bridges to give compounds of similar structure to adducts such as tetrahydrothiophen·HgCl2 or Et2S·2HgCl2. The 1 : 2 adducts are weak addition complexes of the 1 : 1 adducts and mercuric halide. Similar 1 : 1 adducts are formed from the complexes M(π-C5H5)(diolefin)(M = Co or Rh; diolefin = cyclo-octa-1,5-diene or norbornadiene). Nuclear magnetic resonance and infrared spectra of the compounds are reported.