Scorpionates

The First Water-Soluble Copper(I) Calix[6]arene Complex Presenting a Hydrophobic Ligand Binding Pocket: A Remarkable Model for Active Sites in Metalloenzymes

“…The first reason is that the ligands used to mimic the biological active site often lead to water‐insoluble complexes, and their solubilization through synthetic procedures is not an easy task. For instance, tris(pyrazolyl)borate, which is the basis for countless biomimetic complexes,2 is sensitive to hydrolysis, and hydrophilic derivatives would not survive in aqueous solvent 3. The second reason is that biologically relevant species are often reactive to water and must be protected and/or stabilized.…”

Adding to the Family of Copper Complexes Featuring Borohydride Ligands Based on 2-Mercaptopyridyl Units

“…The ligand was based on soft sulfur donor atoms [16], and perhaps more significantly, greater flexibility had been incorporated into the ligand by addition of the extra atom between the boron and the donor atom. It was this greater flexibility within the ligand structure that opened up the potential for activation at the boron bridgehead and formation of metal-borane (metallaboratrane) complexes [17][18][19][20][24][25][26][27], giving rise to reactivity not observed in the analogous polypyrazolylborate ligands [10][11][12][13][14][15][16]. Over the following twenty years since the first report of hydride migration from the boron center of a scorpionate ligand, a number of research groups have focused on new, more flexible borohydride ligands containing a range of supporting units based on nitrogen [28][29][30][31] and other sulfur heterocycles [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46].…”

“…This area of research has provided an expansive and fascinating array of compounds with wide ranging applications. These have been explored in homogeneous catalysis and bioinorganic chemistry, for example [10][11][12][13][14][15][16]. In many examples, the borohydride unit is positioned away from the metal center, playing a spectator role within the complex.…”

“…The ligand was based on soft sulfur donor atoms [16], and perhaps more significantly, greater flexibility had been incorporated into the ligand by addition of the extra atom between the boron and the donor atom. It was this greater flexibility within the ligand structure that opened up the potential for activation at the boron bridgehead and formation of metal-borane (metallaboratrane) complexes [17][18][19][20][24][25][26][27], giving rise to reactivity not observed in the analogous polypyrazolylborate ligands [10][11][12][13][14][15][16].Inorganics 2019, 7, x FOR PEER REVIEW 2 of 11 differences when compared to Trofimenko's original scorpionates. The ligand was based on soft sulfur donor atoms [16], and perhaps more significantly, greater flexibility had been incorporated into the ligand by addition of the extra atom between the boron and the donor atom.…”

Swiatoslaw Trofimenko (1931–2007)

“…After retiring from DuPont, Trofimenko joined the Klaus H. Theopold research group at the Department of Chemistry and Biochemistry at the University of Delaware as a Visiting Scholar. There he continued his research on pyrazolylborates and wrote his book titled “Scorpionates: The Coordination Chemistry of Polypyrazolylborate Ligands” 3…”