Efficient stereochemical regulation of octahedral cobalt(III) complexes by a chiral bidentate ligand. Part 2. Remarkable effect of the chelate-ring size in the stereoselective formation of sym-cis-(ethylenediamine-N,N′-diacetato)(pentane-2,4-diamine)cobalt(III)

Abstract

Efficient Stereochemical Regulation of Octahedral Cobalt(iii) Complexes by a Chiral Bidentate Ligand. Part 2.' Remarkable Effect of the Chelate-ring Size in the Stereoselective Formation of sym-cis-( Et hylened iami ne-A/,"-d iacetato) -(pentane-2,4-d iami ne)cobalt (111) t

Synthesis, spectral, and thermal properties, and crystal structure of cobalt (III) complex derived from Imazameth

“…The involvement of the lactam N(3) in the place of the imidazole-type N(2) atom in metal coordination is surprising, unless deprotonated, the amide nitrogen atoms is not an effective donor. A comparison of the bond lengths in the chelated ring reveals that the pyridine N(1)-Co bond, which is over the long-range side of Co(III)-N bond distance (1.88-1.97 Å ) [40][41][42], is significantly longer than the imidazole N(3)-Co bond. Most probably, this is a consequence of the different basicity of the N(1) and N(3) donors.…”

Prädeterminierte Chiralität an Metallzentren

“…Yashiro und Yano [60,61] verwendeten den achiralen vierzähnigen Liganden L13 a und die enantiomerenreinen Diamin-Liganden (R,R)-L14 und (R,R)-L15 a. Im (L13 a)cobalt(iii)-Komplex des chiralen Liganden (R,R)-L14 ± [Co III (L13 a)((R,R)-L14)] ± war die Stereoselektivität L:D mit 3:97 erstaunlich hoch; beim entsprechenden (R,R)-L15 a-Komplex betrug das L:D-Verhältnis lediglich 60:40. Um die Ursache der hohen Selektivität im ersten Fall herauszufinden, wurden an beiden Isomeren Röntgenstrukturanalysen durchgeführt.…”