Guanidines silver complexes

Data from Synthesis and X-ray structures of silver and gold guanidinate-like complexes. A Au(II) complex with a 2.47 A Au-Au distance, M. D. Irwin, H. E. Abdou, A. A. Mohamed, and J. P. Fackler, Jr., Chem. Commun., 2003, 2882.)... 

It appears that ths method is quite specific and that no serious interference need be expected from other than sulfhydryl-containing substances. It should be pointed out, however, that substances which form stable complexes or insoluble salts with silver ions (e. g., cyanide, iodide, and sulfide) may be expected to interfere. Possible steric impediments to the access of the Ag(NHs) ion to the —SH groups should be kept in mind. The process involved is essentially one of mercaptide formation and the limitations of such a process (particularly with respect to the specificity of the diver mercaptide formation) diould also be kept in mind. The procedure has been applied to the determination of —SH grmips in proteins denatured with guanidine hydrochloride and with urea (24,123). It has been shown that the addition of an excess of standard potasdum p-chloro-mercuribenzoate prior to the titration with silver nitrate effectively blocks... 

---