Control of molecular architecture by use of the appropriate ligand isomer: a mononuclear “corner-type” versus a tetranuclear [2 × 2] grid-type cobalt(iii) complex

Abstract

Employing two isomeric pyrazine-based ligands a [2 x 2] grid-type tetranuclear cobalt(III) complex, incorporating doubly deprotonated (La)2- ligands, and a "corner-type" mononuclear cobalt(III) complex, incorporating neutral H2Lp ligands in a zwitterionic form, have been synthesised and structurally characterised.

Di‐ and Tetranuclear Complexes of Bis‐Tetradentate Pyrimidine‐Based Ligands with All‐Methylene‐ Versus Mixed Methylene/Ethylene‐Linked Arms

“…[1,2] Our research group has developed a range of ligands based around the diazines pyridazine, [3][4][5][6][7][8][9][10] pyrimidine [11][12][13] and pyrazine. [14][15][16][17][18][19][20] 4485 formed in MeOH. Five dimetallic (3Ј-6Ј and 9Ј) and one tetrametallic complex (15Ј) were structurally characterized: the ligands are bis-tetradentate and the metal centres are bridged through the pyrimidine ring.…”

Dinuclear Copper(II) Complexes of Two Homologous Pyrazine‐Based Bis(terdentate) Diamide Ligands

“…70-80 % yield) of the desired SiF 6 2-compounds. The occurrence of SiF 6 2- ions in these compounds, rather than BF 4 -ions, was unexpected but was readily confirmed by the negative ion ESI mass spectrum, which showed a peak at m/z = 123.0 corresponding to the SiF 5 -anion, and the IR spectrum, which showed an intense broad split band (with peaks at 780 and 750 cm -1 ) typical of the SiF 6 2-ion. It has been reported that SiF 6 2-anions can arise in compounds originally containing BF 4 -ions as partial hydrolysis of the latter in the presence of moisture can generate traces of HF, which then react with the glassware to form SiF 6 2-ions.…”

“…Indeed, we have recently reported a cobalt(iii) [2 × 2] grid-type complex of the doubly deprotonated ligand (L 2 ) 2-. [5] Likewise, copper(ii) [6] and nickel(ii) [7] [8] These rather intractable solids have not been further characterised. In contrast, in the absence of added base, reactions Table 2, Table 3 and Table 4).…”

Structural Diversity on Copper(I) Schiff Base Complexes

“…Brooker et al systematically studied on grid complexes of first transition metal ions that exhibit interesting structural, electrochemical and magnetic properties [31,32,[87][88][89][90]. The flat bisbidentate ligand dppn [3,6-bis(2-pyridiyl)pyridazine] has been used for preparation of copper(I) gridlike complexes in 1992 (Scheme 34) [91].…”