The systematic generation of monodentate bridging ethanoates in dinuclear nickel(ii) complexes of asymmetric compartmental ligands

Abstract

The presence of five-membered chelating rings derived from the iminic and aminic pendant arms in dinuclear nickel() complexes of asymmetric compartmental ligands gives rise to syn-syn bidentate ethanoate bridging in these complexes whereas the introduction of a six-membered chelating ring at the iminic binding site induces an ethanoate shift generating a monodentate bridging ethanoate group. DALTON

Hydrogen-bonded mononuclear nickel(II) benzoate complexes: synthesis and structural studies

“…In these complexes, the nickel center is five-coordinate with three nitrogen atoms from the Tp Ph,Me ligand, one nitrogen atom from Pz Ph,Me H and one oxygen atom from the benzoate ligand. The distance between the metal center and bonded oxygen atom of the benzoate ligand is very similar in all of these complexes and lies within the range of 1.983(2)-2.026(3) Å reported as in the literature [8,14]. The distance between the non-bonded oxygen atom and metal center is too large for coordination and shows slight variations from complex to complex ( Table 3).…”

“…The nickel center in this complex is five-coordinate with nickelnitrogen bond distances in the range of 2.045(2)-2.147 (19) Å which is usual for nickel bonded Tp complexes [14,20]. The metal-nitrogen bond distance of coordinated Pz Ph,Me H is almost the same as the Ni-N bond (2,X=H,3,4,5,6,7,8,9,10, Scheme 1 Synthesis of complexes 1-10 Table 2). The Ni-Cl bond distance of 2.306 (7) Å is also in the range of reported complexes [21] and shows its covalent character.…”

“…It is also well known that carboxylate hydrogen-bonding plays an important role in biological systems and is a gateway to molecular organization [2]. The literature shows that dinuclear nickel complexes with bridging carboxylates [3,4] are interesting for their magnetic interactions, whereas the mononuclear complexes are likely to play an important role in modeling the active site of metalloproteins [5][6][7][8]. Examples of structurally characterized nickel-carboxylate complexes are limited in the literature [9][10][11][12].…”

The generation of a trinuclear cobalt (II) core supported by differing tridentate acetate bridges

“…In complex 2 the monodentate acetate bridge is non-symmetricNi (1) (2), of the syn-syn bridging acetate is more open at 127.1(4)°. We have previously noted that the l-acetato-jO,jO 0 :jO bridging mode can be found in dinickel(II) complexes of related asymmetric Schiff base compartmental ligands in which there is a six-membered chelate ring at the iminic binding site [12]. When a five-membered chelate ring was introduced at the iminic binding site double syn-syn acetate bridging, as in 3, was noted.…”

Synthesis and Characterization of Heterotrinuclear Complexes of Nickel and Palladium with Pyridinecarboxylate as Bridging Ligands

“…[1][2][3][4][5][6] The deliberate, stepwise and controlled synthesis of molecular squares and dinuclear macrocycles using pyridinecarboxylates as spacers has been recently reported by Hor et al [7] The versatile carboxylate anion can adopt a wide range of bonding modes including monodentate, symmetric and asymmetric chelating and bidentate and monodentate bridging. [8] It is generally agreed that the carboxylate complexes of the 3d elements, including several examples of nickel derivatives, play an important role in biochemistry. [9] In this paper we report the preparation by two different routes and the spectroscopic behavior of heterotrinuclear pyridinecarboxylate complexes of nickel and palladium in which the two nickel(ii) ions are in a pentacoordinate environment.…”