Rapid Synthesis of a Functional Resin-Supported Scorpionate and Its Copper(I, II), Rhodium(I), and Chromium(III) Complexes

Boron-scorpionates are readily prepared by microwave (MW) assisted methods. Such a method is described here, leading to the rapid preparation of a heterogeneous resin-supported scorpionate as its sodium salt, BdPhTpNa [BdPhTp = phenyltris(1-pyrazolyl)borate covalently bound through the phenyl ring to commercial cross-linked polystyrene resin beads]. Formation of a functional heterogeneous scorpionate was confirmed from the subsequent reactions of several metal complexes. This supported ligand system coordinates a variety of transition metal ions including copper(I and II), chromium(III) and rhodium(I). Chromium(III) provided definitive electronic spectral evidence for supported-TpCr(III) coordination spheres, including reversible ligand-substitution reactions. The copper(I) case exhibited typical scorpionate Cu-I reactivity including spectroscopically characterized (IR and P-31 NMR) complexes with CO, PPh3, and HCCH. Copper(II) provided EPR evidence for heterogeneous scorpionates. The supported rhodium(I) complex was demonstrated to be a recyclable heterogeneous rhodium-scorpionate catalyst. These results all support the conclusion that the immobilized chelate forms coordinatively unsaturated half-sandwich metal complexes (LMn+) capable of efficient ligand-substitution reactions or catalytic activity.