Wasserlösliche Metallkomplexe und Katalysatoren, V. 2,2′‐Bipyridin‐5‐sulfonsäure und metallorganische Komplexe: Spektroskopie und Strukturchemie

Water‐Soluble Metal Complexes and Catalysts, V. — 2,2′‐Bipyridine‐5‐sulfonic Acid and Organometallic Complexes: Spectroscopy and Structures Coplanar orientation of the pyridine rings in 2,2′‐bipyridine‐5‐sulfonic acid (1a) and in metal complexes of this ligand is evident from NMR studies. While the free acid 1a exists as a planar zwitter‐ion the rings of the salts 1b–d (Na⁺, [N(C₄H₉)₄]⁺,[P(C₆H₅)₄)]⁺) and sulfonamides 1f–h (tert‐butyl, benzyl, 2‐pyridylmethyl) are twisted. X‐ray crystal structures determined for four complexes 4e, h, 1, and 10b of the sulfonic acid and sulfonamide derivatives of 2,2′‐bipyridine show that there is no influence of the sulfonic acid and the sulfonamide groups (meta‐position) on the complex chemistry of the chelate ligand. Variation of solubility should, therefore, occur without principal changes of reactivity.