Pseudobases of Metal Complexes Containing Heterocyclic Ligands

Pseudobases of Metal Complexes Containing Heterocyclic Ligands 

Over the past few years, Gillard et a/.361-369 have presented evidence that complexation of 2,2 -dipyridyl and 1,10-phenanthroline and their 

Quantitative rate and equilibrium studies for pseudobase formation by metal complexes are summarized in Table X. Activation parameters for methoxide ion addition to Ru(5-nitro-l,10-phenanthroline)3+ are AH = 10.6 kcal mol-1, AS = —10 cal mol-1 deg-1 and for ethoxide ion addition to the same metal complex are AH = 11.1 kcal mol-1 and AS = — 6.9 cal mol-1 deg-1.365 

Quantitative Data for Pseudobase Formation by Metal Complexes Having Heterocyclic Ligands 

The divalent metal ion complexes of 2,2 -dipyridyl and 1,10-phenan-throline derivatives are much more susceptible to pseudobase formation than the corresponding N-alkyl quaternary cations. Thus, pXR+ 14 for pseudobase formation by the N-methyl monocations of both 2,2 -dipyridyl and 1,10-phenanthroline,46 whereas the Pt2+ complexes of these heterocycles have pKR, values of 9.0 and — 11.5, respectively.361,369 This latter value indicates that Pt(l,10-phenanthroline)i+ is less susceptible to pseudobase formation than the 1,10-phenanthrolinium dications 17 (pKR+ = 9.54) and 18 (pKR+ = 9.17).46 

---

VII. Pseudobases of Metal Complexes Containing Heterocyclic Ligands... 

---