The encapsulation of ferrocyanide by copper(II) complexes of tripodal tetradentate ligands. Novel H-bonding networks incorporating heptanuclear and pentanuclear heterometallic assemblies

Substitution of the weakly binding aqua ligand in [Cu(tren)OH2](2+) and [Cu (tpa)OH2](2+) (tren = tris(2-aminoethyl)amine; tpa = tris(2-pyridylmethyl)a mine) by a cyano ligand on ferricyanide results in the assembly. of heterop olynuclear cations around the cyanometalate core. In water, the reduction o f the Fe-III core to Fe-II generates complexes that feature heteropolycatio ns in which ferrocyanide is encapsulated by the Cu-II moieties: [{Cu(tpa)CN }(6)Fe][ClO4](8)(.)3H(2)O 1, [{Cu(tren)CN}(6)Fe][ClO4](8)(.)10H(2)O 2, [{Cu (tren)CN}(6)Fe][Fe(CN)(6)](2)[ClO4](2)(.)15.8H(2)O 3, and [{Cu(tren)CN}(6)F e][{Cu(tren)CN}(4)Fe(CN)(2)][Fe(CN)(6)](4)(.)6DMSO-21H(2)O 4. The formation of discrete molecules, in preference to extended networks or polymeric str uctures, has been encouraged through the use of branched tetradentate ligan ds in conjunction with copper(II), a metal center with the propensity to fo rm five-coordinate complexes. Complex 3 crystallizes in the monoclinic spac e group P2(1)/c (#14) with a = 14.8674(10), b = 25.9587(10), c = 27.5617(10 ) Angstrom, beta = 100.8300(10)degrees, and Z = 4, and it is comprised of a lmost spherical heptanuclear cations, [{Cu(tren)CN}(6)Fe](8+), whose charge is balanced by two ferricyanide and two perchlorate counteranions. Complex 4 crystallizes in the triclinic space group P1 (#1) with a = 14.8094(8), b = 17.3901(7), c = 21.1565(11) Angstrom, alpha = 110.750(3), beta = 90.206( 2), gamma = 112.754(3)degrees, and Z = 1, and it is comprised of the heptan uclear [{Cu(tren)CN}(6)Fe](8+) cation and pentanuclear [{Cu(tren)CN}(4)Fe(C N)(2)](4+) cation, whose terminal cyano, ligands are oriented trans to each other. The charge is balanced exclusively by ferricyanide counteranions. I n both complexes, H-bonding interactions between hydrogens on primary amine s of the tren ligand, terminal cyano groups of the ferricyanide counterions , and the solvent of crystallization generate intricate 3D H-bonding networ ks.