Coordination, organometallic and related chemistry of tris(pyrazolyl)methane ligands

A New Synthesis of Charge‐Neutral Tris‐Pyrazolyl and ‐Methimazolyl Borate Ligands

“…This comparison indicates that the new neutral ligands are only marginally weaker donors than the corresponding anionic hydrotrisA C H T U N G T R E N N U N G (azolyl)borate ligands. This may be explained by the ability of the attached nmi ring to stabilize a positive charge remotely from the coordinated metal, which may also account for the fact that the [(nmi)B(pyrazolyl) 3 ] ligand is a substantially stronger donor than the similarly neutral tris(pyrazolyl)methane ligand.…”

“…The presence of an extra atom in each arm of the tripod provides a system that forms a bicycloA C H T U N G T R E N N U N G [3.3.3] cage upon k 3 coordination to a metal ion, and this contrasts with the bicyclo-A C H T U N G T R E N N U N G [2.2.2] cage present in Tp ligand complexes. Thus, whereas the latter forms a C 3v -symmetric TpM cage structure containing six-membered rings, angle strain within the eightAbstract: The dimethylamine in the adducts [(HNMe 2 )BA C H T U N G T R E N N U N G (azolyl) 3 ] (azolyl = methimazolyl, pyrazolyl), obtained by reaction of the azole with BA C H T U N G T R E N N U N G (NMe 2 ) 3 , can readily be substituted with a range of nitrogen donors to provide new charge-neutral, tripodal ligands in high yield. This observation has led to a revision of an earlier interpretation of the mechanism of the formation of these species.…”

“…[2] Analogous neutral tripods such as the tris(pyrazolyl)methanes (RC(pz) 3 ) [3] and phosporyl-centered ligands (O=P(pz) 3 ) [4] have also been developed. More recently, a new family of sulfur-donor ligands with the methimazolyl group (1-methylimidazolyl-2-thione) and its derivatives as the donor heterocycles, [HB(methimazolyl) 3 ] À (Tm), has been developed based upon a similar synthetic methodology (Scheme 1).…”

C-Homoscorpionate Oxidation Catalysts—Electrochemical and Catalytic Activity

“…The latter are considerably less well studied than the analogous borate species [3]. However, in the last two decades, mainly driven by improved syntheses [9,10], coordination behavior and physicochemical properties of poly(pyrazol-1-yl)methanes have attracted considerable interest [5][6][7][8] in order to perform the precise tuning of target scorpionates towards a desired function [3,6,7]. Applications of this highly versatile class of metal compounds range from organic synthesis, analytical, bio-inorganic or catalytic chemistry to material sciences [3,[6][7][8][11][12][13][14][15][16][17][18].…”

“…Scorpionate compounds (Figure 1), in particular, poly(pyrazol-1-yl)borates, R 1 BXn(R 2 pz)3−n (pz = pyrazol-1-yl, n = 0 or 1), and poly(pyrazol-1-yl)methanes, R 1 CXn(R 2 pz)3−n (n = 0 or 1), are undoubtedly among the most important N-donor ligands in coordination chemistry [1][2][3][4][5][6][7][8]. The latter are considerably less well studied than the analogous borate species [3].…”