Substitution reactions of a water-soluble metalloporphyrin with azide and 1,1,3,3-tetramethyl-2-thiourea

✍ Scribed by Robert F. Pasternack; Bruce S. Gillies; Julia P. Stromsted

• Publisher: Elsevier Science
• Year: 1978
• Weight: 659 KB
• Volume: 8
• Category: Article
• ISSN: 0006-3061
• DOI: 10.1016/s0006-3061(00)80003-4

✦ Synopsis

The substitution reections of tetrekis+l-N-methylpyridyl)porphinecobdt (III) (CoHITMpyP) with aside and with 1 .1.3.3-tetrametltyl-2-thiourea (TMTU) have been studied as a function of pH at 25" and en ionic strength of 0.5 M. The mechanistic pathway proposed for thiocyanate [l] and pyridine [2] is applicable to these ligands as well once allowance is made for two attacking forms of aside, Na-and HN3. A TMTU axial substituent has about the same influence on the rate of further ligand substitution as does SCN-and a much larger influence than does azide. Similar behavior between bound SCN-

and hound TMTU is also shown in electron-transfer reactions with Ru(NHa)e2+whereas both sulfur-containing ligands enhance the rote relative to the dia'quo complex, the azide complex undergoes reduction an order of magnitude more slowly than does the diaquo complex.