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)(A),V = 9929(5)(A)3, Z= 4, C95H96Cl5F8N3O8.50P4Rh4, Mr = 2280.52, Dc = 1.526 g/cm3, F(000) = 4608 and μ(MoKa) = 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) (A) 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)(A).