1,1':4',1''-Terphenyl-2',5'-dicarb-oxy-lic acid dimethyl sulfoxide-d(6) disolvate.

The asymmetric unit of the title solvate, C(20)H(14)O(4)·2C(2)D(6)OS, contains half of the substituted terephthalic acid mol-ecule and one solvent mol-ecule. The centroid of the central benzene ring in the acid mol-ecule is coincident with a crystallographic inversion center. Neither the carboxyl nor the phenyl substituents are coplanar with the central aromatic ring, showing dihedral angles of 53.18 (11) and 47.83 (11)°, respectively. The dimethyl sulfoxide solvent mol-ecules are hydrogen bonded to the carb-oxy-lic acid groups.

Toward the synthetic control of the HOMO-LUMO gap in binuclear systems: insights from density functional calculations.

Computational methods based on density functional theory have been applied to address the design of tailored HOMO-LUMO gap bimetallic complexes. We focus our attention on the [Cp*Fe-(L)-FeCp*] system, where two ferrocenyl units are linked through the dianion of fused ring ligands such as pentalene, s-indacene, dicyclopenta-[b,g]-naphthalene, dicyclopenta-[b,i]-anthracene and dicyclopenta-[b,l]-tetracene. Our DFT calculations on the title organometallic complexes suggest a controlled decrease in the HOMO-LUMO gap, which is desirable for studies on electron-transfer phenomena, as well as the design potential devices for molecular electronic purposes.

Phenyl 3,5-di-tert-butyl-2-hy-droxy-benzoate.

The title mol-ecule, C(21)H(26)O(3), has a six-membered planar carbon ring as the central core, substituted at position 1 with phen-oxy-carbonyl, at position 2 with hy-droxy and at positions 3 and 5 with tert-butyl groups. The structure shows two independent but very similar mol-ecules within the asymmetric unit. For both independent mol-ecules, the ester carboxyl-ate group is coplanar with the central core, as reflected by the small C-C-O-C torsion angles [179.95 (17) and 173.70 (17)°]. In contrast, the phenyl substituent is almost perpendicular to the carboxyl-ate -CO(2) fragment, as reflected by C-O-C-C torsion angles, ranging from 74 to 80°. The coplanarity between the central aromatic ring and the ester carboxyl-ate -CO(2)- group allows the formation of an intra-molecular hydrogen bond, with O⋯O distances of 2.563 (2) and 2.604 (2) Å.