A new class of biomimetically relevant ‘Scorpionate’ ligands III. The bis(pyrazolyl)methane(phen-2′-ol)s: Synthesis and structural characterization of mono and dinuclear copper(II) complexes

Sodium, magnesium and zinc complexes of mono(phenolate) heteroscorpionate ligands

“…A number of homoleptic transition metal complexes of related N 2 O donor heteroscorpionate ligands have been structurally characterized. 29,30,33 In contrast to 4, these have mutually trans phenolate groups with approximately linear O-M-O linkages and molecular C 2h symmetry. The Mg-O and Mg-N distances in 4 are significantly longer than in the four-coordinate complexes 3 and 6, as a consequence of its higher coordination number.…”

Synthesis and Characterization of a Series of Edge-Sharing Octahedral−Tetrahedral−Octahedral Linear Trinuclear Complexes [M3(L1O)4]2+, Where M = Mn2+, Co2+, Ni2+, Cu2+, and Zn2+and L1OH Is the “Heteroscorpionate” Ligand (2-Hydroxyphenyl)bis(pyrazolyl)methane

“…We have previously described the synthesis and some of the coordination properties of a new class of heteroscorpionate ligands. − These ligands are of the general type L 2 CX, where L = 3(5)-substituted pyrazole and X = functionalized donor, i.e., a substituted phenol or thiophenol. We have shown that the nature of the metal complex formed by these ligands depends on the particular metal involved and the degree of substitution on both the phenyl and pyrazole arms, as well as the ligand-to-metal ratio.…”

A Family of Homo‐ and Heteroscorpionate Ligands: Applications to Bioinorganic Chemistry

“…Therefore we studied the alkylation of LZnSPh complexes where L is one of a series of N 2 X tripodal scorpionates containing phenolate oxygen, alkoxy oxygen, carboxylate oxygen or thiolate sulfur donors respectively in the “X” position designed to mimic the tetrahedral binding site found in all zinc thiolate proteins. By substituting o ‐ N ‐Ac‐thiophenol (known to possess an internal hydrogen bond between the amide and the thiolate sulfur) in place of thiophenol itself as the exogenous fourth ligand, we showed that presence of just a single such H‐bond a) reduces the reactivity of the thiol by as much as 2 orders of magnitude and b) can be used to generate a high degree of regiospecificity in complexes containing multiple potentially alkylatable sites even with a powerful, and hence inherently indiscriminate, electrophile (Figure ). Based on these observations we suggested that the presence of hydrogen bonds between the accessible but unreactive cys 69 or 42 and their absence at cys‐38 could be the means by which the well‐known regiospecifity of Ada is maintained.…”

“…Our major contribution to this field has been in the collection and use of a family of tripodal N 2 X heteroscorpionate ligands which contain all the biologically relevant donor atoms and are isostructural and isoelectronic with Tp (Figure ). While a family of this first generation of heteroscorpionate ligands with varying donor atoms was prepared, they lacked steric bulk and were found to often produce interesting, but not very biomimetic, polynuclear species . A second generation of more useful sterically protected ligands has subsequently been forthcoming (Figure ) and with these we have begun to investigate how donor atom identity affects the properties of the metal center in a series of isostructural and isoelectronic complexes.…”