Bis(pyrazolyl)(thioimidazolyl)borate Ligands:  The Missing Member in the N₃···S₃ Scorpionate Series

Abstract

The anionic bis(pyrazolyl)(thioimidazolyl)borate ligands BpMt(R) with R = tert-butyl and isopropyl were obtained as their potassium salts by reacting potassium tris(pyrazolyl)borate with the corresponding thioimidazoles in the melt at 150 degrees C. They were applied to form some tetrahedral zinc complexes and identified by the crystal structures of (BpMt(t-Bu))ZnCl and (BpMt(i-Pr))Zn-SC(6)H(4)-p-Cl.

Biomimetic Thiolate Alkylation with Zinc Pyrazolylbis(thioimidazolyl)borate Complexes

“…While the preparation of (tripod)ZnSR complexes for the tris(pyrazolyl)borate [13] and bis(pyrazolyl)(thioimidazolyl)-borate tripods [18] is straightforward, in this case it required careful control of the reaction conditions. The high tendency of formation of the bis(ligand)complexes 3 and the oligomeric zinc bis(thiolates) prevented the isolation of most of the desired thiolate complexes with tripod L 2 , and it allowed the isolation of the alkyl-and benzylthiolate complexes of tripod L 1 only when carefully controlling the reaction conditions.…”

“…A complete series of such ligands with substituted thioimidazolyl groups as sulfur donors is available now: after Reglinski's discovery of the tris(thioimidazolyl)borates, [15] Parkin [16] and ourselves [17] introduced the pyrazolylbis(thioimidazolyl)borates, and very recently we added the final member, the bis(pyrazolyl)(thioimidazolyl)borates. [18] Following our introductory study on the alkylation of tris(pyrazolyl)boratozinc thiolates, [13] in the second part of the investigation we used the bis(pyrazolyl)(thioimidzolyl)-boratozinc thiolates. [19] The major, and unexpected, observation of this study was that the thiolate alkylations are slower than those of the tris(pyrazolyl)boratozinc thiolates, despite the increased electron density of the complexes.…”

Copper Complexes of Mono‐ and Ditopic [(Methylthio)methyl]borates: Missing Links and Linked Systems En Route to Copper Enzyme Models

“…Treatment of the monotopic tripod [5] À with CuCl and CuBr 2 results in the formation of complexes K[Cu (5) ((N 2 P), [13,14] (NP 2 ) [15] ) or nitrogen and sulfur donors ((N 2 S), [16] (NS 2 ) [17][18][19][20][21][22] ). These derivatives are most interesting, because they allow a smooth modulation of the coordination environment between the extremes (N 3 ) and (P 3 )/(S 3 ).…”

Zinc Thiolate Complexes of (N,N,S)‐Tridentate Ligands for the Modeling of Thiolate Alkylating Enzymes

“…[8,9] We have reported various tridentate N 2 S ligands [12][13][14][15] as well as pyrazolylborate-derived NS 2 [16] and N 2 S tripods. [17] While we have previously focused on modeling hydrolytic enzymes or alcohol dehydrogenase with their zinc complexes, we are at present using their zinc thiolate complexes for studies of thiolate alkylation. This paper reports our results with the tridentate N 2 S systems L 1 -L 3 .…”