Synthesis of novel tetracarboxylato dirhenium(III) compounds and crystal structure of [Re2(1-adamantylcarboxylate)4Cl2]•4CHCl3

The coordination compounds of the general formula Re-2(L)(4)X-2 (X = Cl. Br; L = 1-adamantyl-carboxylate and 1-adamantylacetate) have been prepared and characterized by means of UV-VIS spectroscopy (2000 cm(-1), delta --> delta*). The crystal and molecular structure of Re-2(AdCOO)(4)Cl-2. 4CHCl(3) solvate was determined by X-ray diffraction. The units Re-2(AdCOO)(4)Cl-2 adopt a centrosymmetric dinuclear array with each metal atom coordinated in a distorted octahedron comprising one rhenium and one chlorine atoms (Re-Cl 2.505(2) Angstrom) and four carboxylate oxygen atoms in the equatorial plane. The rhenium-rhenium separation of 2.2300(5) Angstrom corresponds to quadruple bond between the metal atoms. All Re-O bonds have an almost uniform length (2.017(4) - 2.032(4) Angstrom) and do not differ essentially from the parameters reported for related compounds. The closest environment of the Re2(AdCOO)(4)Cl-2 molecules in the crystal comprises weak Cl---HC hydrogen bonds with the chloroform molecules and significantly shortened van der Waals contacts Cl---Cl, 3.46 Angstrom.