Synthesis of a Series of Rhodium Complexes, TpiPrRhIL2 and TpiPrRhIII(X)(Y)(MeCN), with the Hydridotris(3,5-diisopropylpyrazolyl)borato Ligand (TpiPr) from a Versatile Precursor, (κ3-TpiPr)Rh(coe)(MeCN), and Dependence of κ2−κ3 Interconversion Rate of the TpiPr Ligand on the Chelate Ring Size

The labile Rh(I) species TpiPrRh(coe)(MeCN) (1) was prepared by the reaction of [RhCl(coe)2]2 with KTpiPr followed by crystallization from MeCN. Subsequent treatment of 1 with diphosphines and CO gave square-planar TpiPrRhIL2-type products via replacement of the coe and MeCN ligands. The Rh(III) complexes TpiPrRh(X)(Y)(MeCN) were obtained via oxidative addition of XY and dissociation of the coe ligand. Complex 1 serves as a versatile starting compound for a variety of Rh(I) and Rh(III) complexes containing the TpiPr ligand. In addition, it was found that κ2−κ3 interconversion of the diphosphine complexes TpiPrRh[Ph2P(CH2)nPPh2] becomes slower as the chelate ring size increases (n increases).