ORGANOMERCURY COMPOUNDS .31. PREPARATIONS AND HG-199 NMR-SPECTRA OF ORGANOMERCURY DERIVATIVES OF 2-PHENYLPYRIDINE, BENZO[H]QUINOLINE, 1-PHENYLPYRAZOLE AND 3,4,5-TRIMETHYL-1-PHENYLPYRAZOLE, AND THE X-RAY CRYSTAL-STRUCTURE OF BIS[2-(PYRIDIN-2'-YL)PHENYL]MERCURY

2-(Pyridin-2'-yl)phenylmercuric acetate has been prepared by mercurati on of 2-phenylpyridine. Symmetrization of the corresponding chloride b y alkaline sodium stannite gave bis[2-(pyridin-2'-yl)phenyl]mercury, w hich was also prepared from 2-(2'-aminophenyl)pyridine by the diazo me thod and treatment of the initial product with copper powder and aqueo us ammonia. Mercuration of benzo[h]quinoline and 3,4,5-trimethyl-1-phe nylpyrazole with mercuric acetate followed by treatment with lithium c hloride yielded benzo[h]quinolin-10-ylmercuric chloride and 2-(3',4',5 '-trimethylpyrazol-1'-yl)phenylmercuric chloride respectively. Treatme nt of the former product with tribromide ions gave 10-bromobenzo[h]qui noline. The exchange Grignard reaction between 1-phenylpyrazole and et hylmagnesium bromide to give 2-(pyrazol-1'yl)phenylmagnesium bromide h as been monitored by reactions with benzonitrile and D2O to establish optimum conditions for reaction with mercuric bromide giving bis[2-(py razol-1'-yl)phenyl]mercury The Hg-199 n.m.r. chemical shifts of the ma jority of mercurials are shifted substantially downfield relative to t he corresponding simple phenylmercurials consistent with weak intramol ecular coordination by the heterocyclic nitrogen donor atoms, but a sm all upfield shift is observed for bis[2-(pyrazol-1'-yl)phenyl]mercury. The X-ray crystal structure of bis[2-(pyridin-2'-yl)phenyl]mercury [m onoclinic, space group P2(1)/n, a 12.746(2), b 11.660(2), c 5.698(1) a ngstrom, beta 92.81(1)degrees, V 845.8 angstrom3] shows a centrosymmet ric molecule with strong linear two coordination [Hg-C 2.098(8) angstr om; C-Hg-C 180.0-degrees] and significant but much weaker Hg-N interac tions [Hg-N 2.798(7) angstrom; N-Hg-N 180.0-degrees] giving overall di storted square planar stereochemistry. The phenyl rings are mutually c oplanar, whilst the two pyridin-2'-yl rings are parallel and inclined at 10.8-degrees to the phenyl groups.