Synthesis of Novel Tetracarboxylato Dirhenium(III) Compounds and Crystal Structure of [Re₂(1-Adamantylcarboxylate)₄Cl₂] · 4 CHCl₃

Abstract

The coordination compounds o f the general formula Re₂ (L)₄X₂ (X = Cl, Br; L = 1 -adamantyl-carboxylate and 1 -adamantylacetate) have been prepared and characterized by means of UV-VIS spectroscopy (20000 cm^-1 , δ → δ*). The crystal and molecular structure of Re₂(AdCOO)₄Cl₂ · 4 CHCl₃ solvate was determined by X-ray diffraction. The units Re₂(AdCOO)₄Cl₂ 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) Å) and four carboxylate oxygen atoms in the equatorial plane. The rhenium-rhenium separation of 2.2300(5) Å corresponds to quadruple bond between the metal atoms. All R e-0 bonds have an almost uniform length (2.017(4) -2.032(4) Å) and do not differ essentially from the parameters reported for related compounds. The closest environment of the Re₂(AdCOO)₄Cl₂ 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 Å.