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

Abstract

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 [a] 2465 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 31 P NMR) complexes with CO, PPh 3 , 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 halfsandwich metal complexes (LM n+ ) capable of efficient ligandsubstitution reactions or catalytic activity.

In situ pyrazolylborate ligand synthesis and coordination behaviours in aluminum oxo clusters

“…16 “The third generation” of scorpion ligands have full F substitution on the benzene ring, and through comparison it has been found that there are great differences between the crystal packing and electrical properties of the complexes of perfluorinated and non-fluorinated species. 17 Then, to further expand the range of scorpion ligands, Wagner and coworkers developed “the fourth generation” of scorpion ligands, controlled their space requirements, and designed more flexible (N,N,N) and (N,O,N) types in the conformation of two mixed donors, making the structure more flexible and stable. 18 The above-mentioned scorpion ligands not only are rich in coordination sites, but also have adjustable steric hindrance, which has potential application value in synthetic structures.…”

Immobilization of a Boron Center-Functionalized Scorpionate Ligand on Mesoporous Silica Supports for Heterogeneous Tp-Based Catalysts

“…Replacement of a boron-attached hydride to a suitable functional group might yield a corresponding boron center-functionalized ligand (FG-Tp R ) that is applicable to various conjugate materials, with retention of the facially capping tridentate metal-supporting scaffolds. 3−5…”

“…Notably, the molecular structures of Tp R –metal complexes correlate with the flexibility of the base polymer. 5 On the flexible polymer support, metalation of the immobilized Tp R yields a coordinatively saturated [M(Tp R ) 2 ] species because the flexible polymer backbone results in two approaching Tp R moieties. Although the formed [M(Tp R ) 2 ] sites function as cross-linking points of the polymers, 5b these sites appear to be catalytically inert.…”

“…Both electronic and structural properties of the substituent groups on the R 3 –R 5 positions of the pyrazolyl rings influence the reactivity at the metal center of the resulting complex. , Recently, interest in the modification of the boron center of Tp R has increased. Replacement of a boron-attached hydride to a suitable functional group might yield a corresponding boron center-functionalized ligand (FG-Tp R ) that is applicable to various conjugate materials, with retention of the facially capping tridentate metal-supporting scaffolds. − …”

“…Immobilization of FG-Tp R on organic polymer-based supports has been achieved. Notably, the molecular structures of Tp R –metal complexes correlate with the flexibility of the base polymer . On the flexible polymer support, metalation of the immobilized Tp R yields a coordinatively saturated [M­(Tp R ) 2 ] species because the flexible polymer backbone results in two approaching Tp R moieties.…”