Half a grid is better than no grid: competition between 2,2?:6?,2??-terpyridine and 3,6-di(pyrid-2-yl)pyridazine for copper(ii)

Constable, Edwin C., Decurtins, Silvio, Housecroft, Catherine E., Keene, Tony D., Palivan, Cornelia G., Price, Jason R. and Zampese, Jennifer A. (2010) Half a grid is better than no grid: competition between 2,2?:6?,2??-terpyridine and 3,6-di(pyrid-2-yl)pyridazine for copper(ii). Dalton Transactions, 39 (9), 2337-2343. (doi:10.1039/b923729a). (PMID:20162207)

Abstract

The reaction between Cu(NO(3))(2)center dot 3H(2)O, 2,2':6',2 ''-terpyridine(tpy) and 3,6-di(pyrid-2-yl) pyridazine (1) in a 2 : 2 : 1 molar equivalent ratio in aqueous MeCN in the presence of excess NH(4)PF(6) leads to competition between the assembly of the dinuclear half-grid [Cu(2)(1)(tpy)(2)][PF(6)](4)center dot 2H(2)O and the mononuclear complex [Cu(1)(2)(OH(2))][PF(6)](2). The yield of [Cu(2)(1)(tpy)(2)][PF(6)](4)center dot 2H(2)O has been optimized using microwave conditions. [Cu(1)2(OH(2))][PF(6)](2) can be selectively produced by treating Cu(NO(3))(2)center dot 3H(2)O with 1 (1:2 molar equivalents) in aqueous MeCN in the presence of NH(4)PF(6). The single crystal structures of [Cu(2)(1)(tpy)(2)][PF(6)](4)center dot 4MeNO(2) and [Cu(1)(2)(OH(2))][PF(6)](2) are presented. In the [Cu(2)(1)(tpy)(2)](4+) cation, ligand 1 bridges the two copper(II) centres, each of which is further coordinated by a tpy ligand. The copper(II) coordination geometry is closely associated with the arrangement of the two tpy ligands which engage in efficient face-to-face p-stacking. Magnetic data for crystalline [Cu(2)(1)(tpy)(2)][PF(6)](4)center dot 4MeNO(2) are consistent with a weak antiferromagnetic interaction between the two copper(II) centres. EPR spectroscopic data for a powder sample of [Cu(2)(1)(tpy)(2)][PF(6)](4)center dot 2H(2)O are consistent with the dinuclear structure, but in frozen DMF and DMSO solutions, the data indicate that the dinuclear structure of [Cu(2)(1)(tpy)(2)](4+) is not preserved.

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Contributors

Author: Tony D. Keene

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