Zinc triad metal ion complexes ofNN′S ligandN-(2-pyridylmethyl)-N-(2-(methylthio)ethyl)amine

Abstract

2007) Zinc triad metal ion complexes of NN′S ligand N-(2-pyridylmethyl)-N-(2-(methylthio)ethyl)amine, Main Group Chemistry, 6:3-4, 155-168,The coordination chemistry of divalent zinc triad metal ions with N-(2-pyridylmethyl)-N-(2-(methylthio)ethyl)amine (L) was investigated by X-ray crystallography and proton NMR. Chloride salts yielded non-homologous M(L)Cl 2 complexes. Hg(L)Cl 2 and Zn(L)Cl 2 were fivecoordinate monomers with distorted square pyramidal and trigonal bipyramidal geometries, respectively. Cd(L)Cl 2 formed a six-coordinate polymer with a distorted octahedral geometry. These complexes had similar nearly temperature independent proton NMR spectra suggesting structural differences between them were less extensive in solution due to fluxional processes. Although 1:1 metal to ligand complexes were most thermodynamically stable for the chloride salts at all [M 2þ ]/[L], the thermodynamic stability of [M(L)(NCCH 3 ) x ] 2þ only exceeded that of [M(L) 2 ] 2þ when [M 2þ ] ! [L] with perchlorate salts. Slow intramolecular and intermolecular exchange conditions for [M(L) 2 ] 2þ and slow intermolecular exchange conditions for [M(L)(NCCH 3 ) x ] 2þ were found on the proton chemical shift and in some cases J(M 1 H) time scales. Strong interactions between divalent zinc triad metal ions and thioether ligand components at physiologically relevant temperatures suggest interactions with methionine should be considered in developing a more complete understanding of the bioactivities of these metal ions.

Bis-tetradentate complexes of Cd(ii) and Hg(ii) with N8coordination: structural and NMR comparisons

“…The strong, comparable J ( 199 Hg 1 H) for H g and H h in 3 and 5 are intriguing. This trend was previously reported for [Hg(L1)-(NCCH 3 )](ClO 4 ) 2 and [Hg(L1)Cl 2 ] 2 (HgCl 4 ) in CD 3 CN solution, 23 but for related tripodal (L4) 3 and dipodal pyridyl ligands, 10,42,43 J ( 199 Hg 1 H) have been observed to shrink significantly with the length of the shortest through bond path between 199 Hg and 1 H. Metal chelation to L2 or L3 establishes 3-, 6-and 7-bond Hg to H g pathways and 4-, 5-, and 6-bond Hg to H h pathways. The rigid cyclopentenyl chelate ring keeps the metal ion, H g and H h in roughly the same plane while restraining H h roughly 1.5 Å further from the metal than H g .…”

Plasticity in the copper–thioether bond: Manifestation in blue Cu proteins and in synthetic analogs

“…With pyrazoles, Bouwman found distances of 2.67-2.68 Å [52], whereas Berreau reported much shorter distances of 2.29-2.43 Å [53]. A very long contact of over 2.80 Å was reported by Butcher et al [54]. In almost all cases the coordination geometries are in between trigonal bipyramidal and square pyramidal.…”

Group 12 complexes of 2,6-bis([(2-pyridinylmethyl)thio]methyl)pyridine: Synthesis and characterization by X-ray crystallography and proton NMR

“…Although the d 10 Group 12 metal ions tolerate a wide range of coordination numbers and coordination geometries with simple ligands, multidentate ligands can be effective at limiting intermolecular ligand exchange. [19][20][21][22] Furthermore, the facile intramolecular isomerization commonly observed for mononuclear Group 12 complexes, [19,23] has been suppressed with the pentadentate ligand L'. [24] This paper describes the first solid-and solution-state investigation of all three divalent…”

“…[19-22, 24, 35, 36] The 199 Hg couplings to H c and H h provide rare examples of five-bond coupling between these two nuclei in a coordination compound. [20,22,24] The 1 H NMR spectra of 1, 2 and 3 under slow intermolecular ligand exchange conditions were investigated as a function of temperature to gain insight regarding intramolecular ligand reorganization (Fig. 7).…”