Synthesis and Structure of an Enantiopure Dirhodium Loop with Unusual Axial Coordination

The crystals of enantiopure SS-[cis-Rh2（Ph2C6H4）2（O2CC2F4CO2）]2（（CH3）2CHCH2NH2）3（1） were obtained from the reaction of S-[cis-Rh2（Ph2C6H4）2（CH3CN）6]BF4（S-2） and（Et4N）2（O2CC2F4CO2） in CH2Cl2/CH3OH under the presence of sec-butyl amine.Compound 1 crystallizes in orthorhombic,space group P212121 with a = 16.880（5）,b = 28.728（9）,c = 20.475（6） ,V = 9929（5） 3,Z = 4,C95H96Cl5F8N3O8.50P4Rh4,Mr = 2280.52,Dc = 1.526 g/cm3,F（000） = 4608 and μ（MoKα） = 0.922 mm-1.The final R = 0.0488 and wR = 0.1164 for 17204 observed reflections with I 〉2σ（I） and R = 0.0814 and wR = 0.1374 for all data with absolute structure parameter =-0.04（3）.Compound 1 contains two inherently chiral S-[cis-Rh2（Ph2C6H4）2] moieties which are connected by two（O2CC2F4CO2） dicarboxylate ligands in the equatorial positions.One of the dirhodium units with Rh-Rh distance of 2.5445（8） is further coordinated by a sec-butyl amine in each axial position.Another dirohdium unit has only one axial sec-butyl amine ligand,and its Rh-Rh distance is 2.5079（9） .

An Unusual Organometallic Supramolecule Composed of Chiral Dirhodium Units and Sulfato Bridging Ligands

A chiral supramolecular compound （H3O）{[cis-Rh2（（C6H5）2P（C6H4））2（SO4）- （DMF）]2（μ- OC2H5）}·6C2H5OH （1） has been synthesized and characterized by X-ray single-crystal analysis. Compound 1 crystallizes in monoclinic, space group C2/c with a = 26.752（3）, b = 13.5868（16）, c = 26.611（3） A, β = 103.891（2）°, V= 9389.5（19）A^3, Z = 4, C92H114N2O18P4Rh4, Mr = 2135.49, Dc = 1.511 g/cm^3, F（000） = 4384 and μ（MoKa） = 0.870 mm^-1. The final R = 0.0441 and wR = 0.1186 for 8283 observed reflections with I 〉 2σ（I） and R = 0.0567 and wR = 0.1290 for all data. The structure of the compound is unique. It contains two inherent chiral {c/s-Rh2[（C6H5）2P（C6H4）]2}^2＋ units which are connected not only in the equatorial positions by two sulfato ligands, but also in two of their axial positions by a μ2 ethoxide anion. The remaining axial positions of Rh2^4＋ units in 1 are occupied by the DMF molecules. The sulfato ligands act as P4 tridentate bridges to connect the Rh2^4＋ units. The Rh-Rh metal-metal bond distances are comparable to those in analogous dirhodium compounds.