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).

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.

[1]  J. Lehn,et al.  Copper(II) dinuclear pyrazine-based rack-type complexes: preparation, structure, and magnetic properties. , 2009, Inorganic chemistry.

[2]  M. Neuburger,et al.  Substituent Effects in the Solid‐State Assembly of Silver(I) Complexes of 4‐Substituted 3,6‐Di(2‐pyridyl)pyridazines , 2008 .

[3]  G. Sheldrick.  A short history of SHELX. , 2008, Acta crystallographica. Section A, Foundations of crystallography.

[4]  F. Lloret,et al.  Ligand effects on the structures and magnetic properties of tricyanomethanide-containing copper(II) complexes. , 2007, Dalton transactions.

[5]  C. Housecroft,et al.  What is the coordination number of copper(II) in metallosupramolecular chemistry , 2006 .

[6]  J. Bacsa,et al.  Anion-pi interactions as controlling elements in self-assembly reactions of Ag(I) complexes with pi-acidic aromatic rings. , 2006, Journal of the American Chemical Society.

[7]  M. Neuburger,et al.  Self-assembly of a novel pentanuclear centred-tetrahedral silver species. , 2004, Chemical communications.

[8]  H. Zimmermann,et al.  Structure and dynamics of copper complexes with 2,2′:6′,2″-terpyridines in glassy matrices , 2003 .

[9]  B. Kariuki,et al.  Structural diversity in silver(I) complexes of 3,6-di(2-pyridyl)pyridazines , 2003 .

[10]  L. Shimon,et al.  Chelation versus Cyclometalation in a Cationic Dppn−RhI Complex − A Unique Rearrangement of Norbornadiene via C−H Activation of the Pyridazine Ring , 2003 .

[11]  W. Kaim.  The coordination chemistry of 1,2,4,5-tetrazines , 2002 .

[12]  Robin Taylor,et al.  New software for searching the Cambridge Structural Database and visualizing crystal structures. , 2002, Acta crystallographica. Section B, Structural science.

[13]  N. Sung,et al.  Bis[3,6-bis(6-methyl-2-pyridyl)pyridazine-κ2N2,N3]chlorocopper(II) perchlorate , 2001 .

[14]  C. J. Matthews,et al.  Dinuclear and tetranuclear copper(II) complexes with bridging (N–N) diazine ligands: variable magnetic exchange topologies , 2000 .

[15]  C. Sheu,et al.  Tris[3,6‐bis(2‐pyridyl)pyridazine‐N1,N6]nickel(II) diperchlorate 0.11‐hydrate , 1999 .

[16]  B. Hathaway,et al.  Crystal structures, electronic properties and structural pathways of thirty [Cu(bipy)2X][Y] complexes, where X = Cl–, Br– or I–† , 1999 .

[17]  J. Osborn,et al.  Rhodium (I) complexes of the dppn ligand, 3,6-bis (2′-pyridyl) pyridazine and X-ray structure of [Rh (CO) (dppn) (PPh 3 ) ] (PF 6 ) , 1998 .

[18]  M. Hill,et al.  Steric Modulation of Electrocatalytic Benzyl Alcohol Oxidation by [Ru(trpy)(R(2)dppi)(O)](2+) Complexes. , 1998, Inorganic chemistry.

[19]  K. Rissanen,et al.  Multicomponent Self-Assembly: Generation of Rigid-Rack Multimetallic Pseudorotaxanes. , 1997, Inorganic chemistry.

[20]  Louis J. Farrugia,et al.  ORTEP-3 for Windows - a version of ORTEP-III with a Graphical User Interface (GUI) , 1997 .

[21]  G. Denti,et al.  X-ray crystal and molecular structure of [3,6-bis(2-pyridyl)pyridazine-N1,N2]bis(triphenylphosphine) copper(I) hexafluorophosphate , 1997 .

[22]  M. Ward,et al.  Synthesis of the potentially pentadentate ligand 6,6″-bis(2-hydroxyphenyl)-2,2′ :6′,2″- terpyridine (H2L) and the crystal structure and magnetic properties of [{Cu(HL)}2][PF6]2·5MeCN , 1995 .

[23]  T. Rojo,et al.  Crystal structure, spectroscopic and magnetic properties of two unusual compounds: [Cu(terpy)(N3)Cl] and [{Cu0.75Ni0.25(terpy)(N3)2}2]·2H2O (terpy = 2,2′ : 6′,2″-terpyridine) , 1994 .

[24]  T. Rojo,et al.  Synthetic strategy, magnetic and spectroscopic properties of the terpyridine complexes [Cu(terpy)X(H2O)n]Y (X = NCO, NCS or N3; n= 0 or 1; Y = NO3 or PF6). Crystal structures of the azidenitrate and azidehexafluoro-phosphate , 1993 .

[25]  J. Osborn,et al.  Self‐Assembly of a Cu4 Complex with Coplanar Copper(I) Ions: Synthesis, Structure, and Electrochemical Properties , 1992 .

[26]  D. Jameson,et al.  An improved, two-step synthesis of 2,2′:6′,2″-terpyridine. , 1991 .

[27]  M. Ghedini,et al.  Heterobinuclear nitrosyl complexes. Part 2. Crystal structures of [(Ph3P)2(NO)Ir(µ-dppn)(µ-Cl)PdCl][PF6]2 and [(Ph3P)Cl2Ir(µ-NO)(µ-dppn)PdCl]PF6[dppn = 3,6-bis(2′-pyridyl)pyridazine] , 1990 .

[28]  G. Denti,et al.  cis-Dicarbonyl-trans-dichloro[3,6-bis(2-pyridyl)pyridazine]ruthenium(II) (1) and cis-dicarbonyl-cis-dichloro[3,6-bis(2-pyridyl)pyridazine]ruthenium(II) (2) , 1988 .

[29]  M. Ghedini,et al.  Rhodium(III) cis-dihydrido complexes with 3,6-bis(2'-pyridyl)pyridazine (dppn) and bidiazines. Crystal and molecular structure of [Rh(H)2(dppn)(PPh3)2]PF6•CH2Cl2 , 1988 .

[30]  M. Ghedini,et al.  Iridium(III)cis-dihydrido complexes with 3,6-bis(2′-pyridyl)pyridazine. Crystal structure of the pyridazinyl complex [{IrH2(PPh3)2}2{µ-C4HN2(C5H4N)2-3,6}]PF6 , 1988 .

[31]  G. Munno,et al.  Aqua-μ-chloro-trichloro-μ-[3,6-di(2-pyridyl)pyridazine]-dicopper(II), [Cu2Cl4(H2O)(C14H10N4)] , 1984 .

[32]  G. Denti,et al.  Aquadichloro-μ-[3,6-di(2-pyridyl)pyridazine-N,N',N'',N''']-μ-hydroxo-nitrato-O-dicopper(II) dichloro-μ-[3,6-di(2-pyridyl)pyridazine-N,N',N'',N''']-μ-hydroxo-μ-nitrato-O,O'-dicopper(II) sesquihydrate, {[Cu2Cl2(OH)(NO3)(C14H10N4)(H2O)][Cu2Cl2(OH)(NO3)(C14H10N4)]}.1.5H2O , 1984 .

[33]  C. Mealli,et al.  Polynuclear complexes of copper(II) with the tetra-aza ligand 3,6-bis(2′-pyridyl)pyridazine(L). Crystal structure of the bromine derivative [Cu2L(OH)Br3]n , 1984 .

[34]  A. W. Addison,et al.  Synthesis, structure, and spectroscopic properties of copper(II) compounds containing nitrogen–sulphur donor ligands; the crystal and molecular structure of aqua[1,7-bis(N-methylbenzimidazol-2′-yl)-2,6-dithiaheptane]copper(II) perchlorate , 1984 .

[35]  S. Eaton,et al.  Use of the ESR half-field transition to determine the interspin distance and the orientation of the interspin vector in systems with two unpaired electrons , 1983 .

[36]  G. Munno,et al.  Poly{aquadichloro[3,6-di(2-pyridyl)pyridazine]-μ-hydroxo-dicopper(II) chloride dihydrate},{[Cu2(C14H10N4)Cl2(H2O)(OH)]Cl}n.2nH2O , 1983 .

[37]  M. Ghedini,et al.  Synthesis and crystal structure of the mixed iridium(III) and copper(II) complex, [IrCl(PPh3)2(µ-dppn)(µ-NO)CuCl][PF6]2, [dppn = 3,6-bis(2′-pyridyl)pyridazine], with a nitrosyl group bridging two different metals , 1983 .

[38]  M. Ghedini,et al.  Synthesis and structure of chlorobis[3,6-di(2-pyridyl)pyridazine]copper(II) chloride pentahydrate , 1982 .

[39]  G. Germain,et al.  Bis(2,2'-6',2''-terpyridine)copper(ii) Hexafluorophosphate , 1982 .

[40]  G. Denti,et al.  Synthesis and characterization of dinuclear copper(II) complexes. Crystal structure of aquatrichlorohydroxo-3,6-bis(2′-pyridyl)pyridazinedicopper(II) , 1982 .

[41]  A. B. Blake,et al.  Crystal structure of an eight-co-ordinate manganese complex: bis-(3,4-di-2-pyridylpyridazine)dinitratomanganese(II) , 1975 .

[42]  F. Case,et al.  The Synthesis of Some Pyridylpyridazines and -pyrimidines1 , 1961 .

[43]  K. Bowers,et al.  Anomalous paramagnetism of copper acetate , 1952, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.