Polynuclear and one-dimensional cyanide-bridged heterobimetallic complexes: synthesis, crystal structures and magnetic properties

Abstract

Three new heterobimetallic cyanide-bridged complexes, {[Ni(L 1)][Ag(CN) 2 ]}[Ag(CN) 2 ] • 2H 2 O (2), {[Mn(L 2)][Ag(CN) 2 ]} • 1.5H 2 O (3) and {[Mn(L 3)(H 2 O)] 2 [Ag(CN) 2 ]}ClO 4 • 2H 2 O (4) (L 1 = 2,7,12-trimethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),13,15-triene; L 2 = N,N'-1,3-propylenebis(5-chlorosalicylideneiminate); L 3 = N,N'-1,2-propylene-bis(5-bromosalicylideneiminate)), have been assembled using for the first time a new polyaza macrocycle nickel(II) compound [Ni(L 1)](ClO 4) 2 (1), or Schiff-base manganese(III) compounds and K[Ag(CN) 2 ]. Single crystal X-ray diffraction analysis reveals that complexes 2 and 3 can be characterized as one-dimensional cationic and neutral single chain structure, respectively. Complex 3 forms a three-dimensional network via weak inter-chain Ag…Ag interactions. Complex 4 belongs to a cyanide-bridged bimetallic sandwich-like cationic trinuclear structure containing Mn 2 Ag core with free ClO − 4 as a counter anion, indicating that the Schiff-base ligand has an obvious influence on the structure of the cyanide-bridged complexes formed. Investigation of the magnetic susceptibilities of the cyanide-bridged Ag-Ni(II)/Mn(III) complexes showed the weak anti-ferromagnetic interaction between neighboring paramagnetic Ni(II) or Mn(III) ions bridged by the long NC-Ag-CN unit. From the best-fit of the magnetic susceptibility data of complexes 2 and 4 the magnetic coupling constant was determined to be J = −0.51 and −0.78 cm −1 , respectively.

Electrocatalytic Nitrite Reduction in Neutral Water with Ni(II) and Co(II) Macrocycle Complexes: Catalytic Evaluation and Mechanistic Elucidation

“…The results for the optimization of 1 were consistent with the experimentally determined single-crystal X-ray analysis. [24] Furthermore, the frontier molecular orbitals that displayed significant d-orbital contribution were as expected for the square planar Ni(II) geometry (Figure S22). In particular, the highest occupied molecular orbital (HOMO, MO87) was essentially the Ni d z 2 and HOMO-1, HOMO-2, and HOMO-3 corresponded with the d yz , d xz , and d xy orbitals, respectively.…”

“…Similarly, the known Co(II) complex ( 2 ) was isolated as red crystals [29] . The single crystal X‐ray structure of 1 was reported to consist of the expected 14‐membered macrocycle which adopted a planar, tetradentate distorted square planar coordination environment for the Ni(II) center [24] …”

“…[29] The single crystal X-ray structure of 1 was reported to consist of the expected 14-membered macro-cycle which adopted a planar, tetradentate distorted square planar coordination environment for the Ni(II) center. [24] The cyclic voltammograms, in the cathodic region, of complexes 1 and 2 in acetonitrile are shown in Figure 1. The Ni complex 1, displayed a reversible redox event at E 1/2 = À 0.52 V and a reversible event at E 1/2 = À 1.10 V. The electrochemistry of the analogous complex of Ni possessing the supporting tetraazamacrocycle, 2,12-dimethyl-3,7,11,17tetraazabicyclo [11.3.1]heptadeca-1(17),2,11,13,15-pentaene, with the amino group as an NH moiety rather than the NMe group, has been thoroughly investigated.…”

“…Complex ( 1 ) was designed around a tetraazamacrocyclic supporting ligand, consisting of a tridentate redox active bis(imino)pyridine moiety coupled with a tertiary amine donor site (Scheme 1). [24] We also report on the electrocatalytic performance of the Co(II) analog of this species, thus providing a unique comparison of catalyst performance. Furthermore, this supplements the existing report on the catalytic behavior of the Co(III) complex with a similar tetracoordinate ligand having an NH group rather than the NMe function of 2 [16] …”

Three Chiral Cyanide-Bridged Cr–Cu Complexes: Synthesis, Crystal Structures and Magnetic Properties

“…Among which, as one of the well-known magnetic transfer groups, cyanide groups usually exhibit unique advantages when assembling bimetallic or even trimetallic cyanide-bridged magnetic complexes. [5][6][7][8][9][10][11][12][13][14][15][16] Although there are many combinations of different magnetic carriers for cyanide-bridged complexes, the Cr III -Cu II system still receives much attention and many cyanide-bridged Cr III -Cu II complexes with interesting magnetic properties such as sin-gle-molecule magnets, single-chain magnets, spin crossover magnets and photo switchable magnets have been reported. [17][18][19][20] Compared with the cyanide-bridged heterometallic Fe III -M (M = Cu(II), Ni(II), Mn(II), Mn(III), et al) complexes, [21][22][23][24][25][26][27] the cyanide-bridged heterometallic Cr III -M complexes are still limited due to the shortage of stable and suitable cyanidochromate(III) building blocks.…”