title: 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).
abstract: The reaction between Cu(NO(3))(2).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).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).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).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).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 pi-stacking. Magnetic data for crystalline [Cu(2)(1)(tpy)(2)][PF(6)](4).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).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.
authors.affiliation: Department of Chemistry, University of Basel, Spitalstrasse 51, CH-4056, Basel, Switzerland. edwin.constable@unibas.ch
authors.forename: Edwin C
authors.initials: EC
authors.lastname: Constable
authors.forename: Silvio
authors.initials: S
authors.lastname: Decurtins
authors.forename: Catherine E
authors.initials: CE
authors.lastname: Housecroft
authors.forename: Tony D
authors.initials: TD
authors.lastname: Keene
authors.forename: Cornelia G
authors.initials: CG
authors.lastname: Palivan
authors.forename: Jason R
authors.initials: JR
authors.lastname: Price
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Zampese
mesh_terms: D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D011724:Pyridazines / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: C517923:(2,2'-6',2'')-terpyridine; C548937:3,6-di(pyrid-2-yl)pyridazine; D009942:Organometallic Compounds; D011724:Pyridazines; D011725:Pyridines; D003300:Copper