The coordination chemistry of divalent cobalt, nickel and copper. Part V: Five-coordinate complexes of copper dichloride with new pyridine dicarboxamide ligand

Syntheses and X-ray crystal structures of five- and six-coordinate copper(II) complexes of N,N,N′,N′-tetraalkylpyridine-2,6-dicarboxamides containing–OClO3 and–OSO2CF3 counter ions

“…A systematic study of steric and electronic effects on the formation of lanthanide complexes with neutral tridentate N,N,N 0 ,N 0 -tetraalkylpyridine-2,6-dicarboxamides(O-daap) (scheme 1) shows a reduced affinity with increasing size of R on the terminal carboxamide side arms [17,18]. Gracia-Lozano et al [19,20] and de Preez et al [21,22] have also reported structural studies on the complexes of these ligands with a number of first-row transition metals. Our interest in N,N,N 0 ,N 0 -tetraalkylpyridine-2,6-dicarboxamide(O-daap) and N,N,N 0 ,N 0 -tetraalkylpyridine-2,6-dithiocarboxamide(S-daap) (scheme 1) [23][24][25][26] has been threefold: first, to study the effect of steric crowding brought by employing various alkyl groups at the terminal carboxamide side arms; second, to investigate the effect of change in the donors in the two side arms on coordination geometry [23][24][25][26], and third, the role played by counter ions, such as -OClO 3 , -OSO 2 CF 3 , and -ONO 2 , in determining the geometry around the metal.…”

“…Upon deprotonation of the carboxamide, nitrogens chelate to metal ions and provide complexes with a range of coordination numbers, nuclearities, and geometries. Tridentate ligands containing fully substituted tetraalkyl/aryl pyridine-2,6-dicarboxamide [1,[17][18][19][20][21][22][23][24][25] use both the carbonyl oxygens and pyridine nitrogen, as hindered C-N bond rotation renders the amide nitrogens almost inactive. A systematic study of steric and electronic effects on the formation of lanthanide complexes with neutral tridentate N,N,N 0 ,N 0 -tetraalkylpyridine-2,6-dicarboxamides(O-daap) (scheme 1) shows a reduced affinity with increasing size of R on the terminal carboxamide side arms [17,18].…”

Coordination Chemistry of N,N,N′,N′‐Tetraethylpyridine‐2,6‐dithiocarboxamide (S‐dept) – X‐ray Crystal Structures and Magnetic Properties of [Co(S‐dept)X2] (X = Br, I, and NCS)

“…[1,2] The symmetrical tertiary amide side arms at the 2-and 6-positions of the central pyridine ring provide a variety of novel ONO-tridentate receptors for binding to metal ions (II). [2] The inflexibility of the ligand in these systems has been one of the important factors leading to the isolation of low-symmetry five-coordinate complexes of Cu II , Co II , Ni II [3][4][5][6] and nine-coordinate complexes of lanthanide ions. [2] Steric and electronic consequences brought by peripheral substitutions to the terminal carboxamide side arms have been well illustrated by Piguet et al [2] on the complexation of Ln III ions.…”