Coordination chemistry of poly(thioether)borate ligands

Abstract

This review traces the development and application of the tris(thioether)borate ligands, tripodal ligands with highly polarizable thioether donors. Areas of emphasis include the basic coordination chemistry of the mid-to-late first row transition metals (Fe, Ni, Co, Cu), and the role of the thioether substituent in directing complex formation, the modeling of zinc thiolate protein active sites, highspin organo-iron and organo-cobalt chemistry, the preparation of monovalent complexes of Fe, Co and Ni, and dioxygen and sulfur activation by monovalent nickel complexes.

Synthesis, Molecular Structure, and Physical Properties of the Complexes [{PhB(pz)2(CH2SMe)}2M] (M = MnII, FeII; pz = pyrazol‐1‐yl) Containing a Novel [N,N,S]‐Heteroscorpionate Ligand

“…These data suggest that T 1/2 is in the region of 180°C. In the crystal lattice, the related [S,S,S] complex [{PhB(CH 2 SMe) 3 . [26] The magnetic moment of 2 is higher than that of the tris(pyrazol-1-yl)borate complex [{PhB(pz) 3 } 2 Fe], which has been reported to be fully diamagnetic in CDCl 3 at room temp.…”

“…Single crystals were grown from pentane/toluene (2) and hexane/benzene (3). Crystal data and details of the structure determinations are summarized in Table 1.…”

“…For example, the introduction of appropriate substituents into the 3-positions of the pyrazolyl rings allows extensive control over the steric demand of the ligand and thus over its ability to kinetically stabilize reactive complex frag-TZVPP//B3LYP-D/SVP level) has been used to evaluate relative energies of the cis and trans isomers of 2 in their highspin and low-spin states. Theoretical and experimental investigations have been extended to the related literatureknown homoleptic Fe II complexes [{PhB(pz) 3 ments. By contrast, an adjustment of the ligand field strengths of tris(pyrazol-1-yl)borates is much harder to achieve, because electronic substituent effects on the donor properties of the pyrazolyl rings turned out to be rather modest.…”

“…Tris(pyrazol-1-yl)borate ligands {"scorpionates"; [RB(pz) 3 ] -} have found widespread use in organometallic and coordination chemistry with applications ranging from modeling active sites of metallo-enzymes through catalysis to materials sciences. [1,2] Owing to the modular synthesis approach, extensive modifications can easily be made to the ligand framework in order to optimize it for a given purpose.…”

“…The chemistry of these ligands was pioneered by Riordan, who described the synthesis and coordination behavior of derivatives with x = 0 and 1. [3][4][5][6][7][8][9][10][11][12] In subsequent studies, the Riordan group used selected examples of the new ligand class to prepare synthetic models for the zinc sites in methionine synthases. [10] One focus of our own interests is the development of artificial analogs of the copper-containing enzymes dopamine β-monooxygenase (DβM) and peptidylglycine α-hydroxylating monooxygenase (PHM) as well as the detailed mechanistic understanding of the reactivity patterns of such species.…”