ABSTRACT
A series of 1,n-dioxa[n](2,7)pyrenophanes (n = 7-12) with increasingly nonplanar pyrene moieties was synthesized by a 9-10 step sequence starting from 5-hydroxyisophthalic acid. The crystal structure of each member of this series was determined crystallographically. Several spectroscopic properties were found to vary with the extent of the nonplanarity of the pyrene unit. The way in which the distortion from planarity of the pyrene system influences its pi-electron delocalization was investigated by using two quantitative descriptors of aromaticity based on geometry (HOMA) and magnetism (magnetic susceptibility and NICS). Both methods suggest that the aromaticity of the pyrene moiety is diminished only slightly upon increasing the bend angle theta from 0 degrees to 109.2 degrees.
ABSTRACT
The ligand 1-oxa-4,7-dithiacyclononane (L) and its complexes [Pd(L)Cl(2)], [Cu(L)(2)][ClO(4)].CH(3)CN, [Cu(L)Br](2), and [Co(L)(2)][ClO(4)](2).2CH(3)NO(2) have been prepared. Crystal data are as follows. For monoclinic [Pd(L)Cl(2)], C(6)H(12)Cl(2)OPdS(2): space group P2(1)/n; a = 8.464(2), b = 12.199(2), c = 10.384(2) Å; beta = 105.09(1) degrees; Z = 4; R = 0.024, R(w) = 0.033 for 1721 reflections. For monoclinic [Cu(L)(2)][ClO(4)].CH(3)CN, C(14)H(27)ClCuNO(6)S(4): space group P2(1)/n; a = 7.743(2), b = 19.515(5), c = 15.017(2) Å; beta = 102.85(2) degrees; Z = 4; R = 0.036, R(w) = 0.038 for 3124 reflections. For triclinic [Cu(L)Br](2), (C(6)H(12)BrCuOS(2))(2): space group P&onemacr;; a = 7.809(5), b = 8.880(3), c = 7.567(2) Å; alpha = 92.44(3), beta = 102.85(2), gamma = 99.30(4) degrees; Z = 2; R = 0.027, R(w) = 0.027 for 1494 reflections. For monoclinic [Co(L)(2)][ClO(4)](2).2CH(3)NO(2), C(14)H(30)Cl(2)CoN(2)O(14)S(4): space group P2(1)/c; a = 10.333(3), b = 14.293(6), c = 9.365(4) Å; beta = 100.89(3) degrees; Z = 2; R = 0.067, R(w) = 0.058 for 1517 reflections. The ligand displays a variety of conformations in these structures. The palladium complex does not undergo 1,4-heteroatom binding site fluxional processes but does dissociate in dimethyl sulfoxide. An apical Pd.O (2.968(3) Å) interaction has been detected by both NMR and X-ray studies. The Cu(I) cation is tetrahedral with a [2+2] mode of ligand coordination. [Cu(L)Br](2) involves two Br bridges between coppers and two thioether sulfurs from a ligand to complete each copper's tetrahedral coordination sphere. Surprisingly, the cyclic voltammetric behavior of the copper complexes is similar to that of 1,4,7-trithiacyclononane complexes. The cation [Co(L)(2)](2+) is pseudooctahedral with nearly regular angles at cobalt but a long (2.235(6) Å) Co-O bond due to Jahn-Teller distortion. The complex [Co(L)(2)][ClO(4)](2) is magnetically dilute and low-spin over the temperature range 5-292 K.
ABSTRACT
Macrocyclic dicopper(II) complexes derived from 2,6-di(R)formylphenols and various linking diamines are surveyed and their magnetic and structural properties assessed. For those systems with "flat" dinuclear centers and no electronic perturbations associated with electron-withdrawing ligands or ligand groups, the complexes exhibit a "straight-line" relationship between exchange integral and phenoxide bridge angle. Within the angle range 98.8-104.7 degrees, 11 complexes are included with -2J in the range 689-902 cm(-)(1). When electron-withdrawing species are present, either as ligands or as groups bound to the macrocycle itself, considerable suppression of the antiferromagnetic exchange component is observed. Single-crystal X-ray diffraction studies are reported for three complexes. [Cu(2)(L1)(H(2)O)(2)]F(2)(CH(3)OH)(2) (1) crystallized in the triclinic system, space group P&onemacr;, with a = 8.1878(5) Å, b = 9.0346(7) Å, c = 10.4048(7) Å, alpha = 103.672(6) degrees, beta = 101.163(5) degrees, gamma = 104.017(5) degrees, and Z = 1. [Cu(2)(L2)Cl(2)] [Cu(2)(L2) (H(2)O)(2)]Cl(ClO(4)).5.5H(2)O (2) crystallized in the monoclinic system, space group P2(1)/n, with a = 14.4305(5) Å, b = 24.3149(8) Å, c = 18.6584(8) Å, beta = 111.282(3) degrees, and Z = 4. [Cu(2)(L3)(H(2)O)(2)](BF(4))(2) (3) crystallized in the triclinic system, space group P&onemacr;, with a = 8.6127(4) Å, b = 8.6321(7) Å, c = 10.8430(10) Å, a = 74.390(10) degrees, beta = 86.050(10) degrees, gamma = 76.350(10) degrees, and Z = 2. Square pyramidal copper ion stereochemistries are observed in all cases, with axially coordinated halogens or water molecules. Strong antiferromagnetic exchange is observed for all complexes (-2J = 784(8) cm(-)(1), Cu-O-Cu 103.65(10) degrees (1); -2J = 801(11) cm(-)(1), Cu-O-Cu 102.4(3), 107.5(3), 102.9(3), 106.1(3) degrees (2); -2J = 689(3) cm(-)(1), Cu-O-Cu 98.8(4) degrees (3)). The presence of electron-withdrawing CN groups on the periphery of the macrocyclic ligand leads to substantially reduced antiferromagnetic exchange.
