Syntheses and properties of Re(III) complexes derived from hydrotris(1-pyrazolyl)methanes: molecular structure of [ReCl2(HCpz3)(PPh3)][BF4]

Pyrazole or tris(pyrazolyl)ethanol oxo-vanadium(IV) complexes as homogeneous or supported catalysts for oxidation of cyclohexane under mild conditions

“…Such a type of behaviour had been shown for the vanadium complex [VO 2 (3,5-Me 2 Hpz) 3 ][BF 4 ] derived from reaction of [VO(OEt) 3 ] with HC(3,5-Me 2 pz) 3 [6k]. Other cases of metal-induced cleavage of such a type of bond have been reported, namely the C N bond rupture in HC(pz) 3 or HC(3,5-Me 2 pz) 3 by the benzoylhydrazido rhenium(V) chelate [25] or in bis(pyrazolyl)propane (CH 3 ) 2 C(pz) 2 by Pt(II) complexes [26,27], namely [PtCl 2 (RCN) 2 ] (R = Me or Ph) or K 2 [PtCl 4 ]. In all the reported cases, the way the cleavage reaction occurs has not been established.…”

Synthesis, Reactivity, X‐ray Crystal Structures and Electrochemical Behaviour of Water‐Soluble [Tris(pyrazolyl)borato]ruthenium(II) Complexes of 1,3,5‐Triaza‐7‐phosphaadamantane (PTA)

“…[31] However, each pyrazolyl arm of Tp is a slightly weaker electron donor than pyrazole itself (E L = 0.20 V vs. NHE). Application of Equation (1), using the estimated E L values, to the above-mentioned unassigned low-intensity oxidation waves at 1.…”

C-Homoscorpionate Oxidation Catalysts—Electrochemical and Catalytic Activity

“…Their measured redox potentials in volts vs. saturated calomel electrode (V vs. SCE) and the eventual reversibility of the redox process, are indicated in Table 1. All authors found that C-homoscorpionate ligands are electrochemically inert in the potential range of −2.0 V to 2.0 V vs. SCE, at the used experimental conditions [46,[49][50][51][52][53][54]89,[91][92][93], thus no ligand centered oxidation or reduction has been reported to date.…”

“…Tris(pyrazol-1-yl)methane E L /V vs. SHE a HC(pz) 3 0.14 {SO 3 C(pz) 3 The electrochemical E L Lever parameters for tris(pyrazol-1-yl)methane ligands [23,51,52,54] to date, found possible to estimate from the oxidation potential values of C-homoscorpionate complexes, by applying the linear (valid for octahedral complexes) relationship (1) and considering its extension to square-planar coordination and to full-and half-sandwich complexes [28,[99][100][101][102][103], are presented in Table 2. These values correspond to partial E L parameters assigned to each metal ligated arm (2-electron-donor) of the scorpionate ligand.…”

“…A systematic investigation of the coordination behavior of new C-scorpionates, as well as some of the known ones, toward a variety of transition metals (e.g., V [44,[46][47][48][49], Mo [17,19,50], Re [51,52], Fe [44,46,49,53], Ru [54], Co [12,13], Ni [44,49,55], Pd [44], Cu [43,45,46,56,57], Ag [14], Au [58] or Zn [44,56]) followed, leading to new classes of complexes exhibiting different types of coordination modes (Figures 4 and 5). Like the pincer of a scorpion, these versatile tripodal ligands bind metal centers with nitrogen atoms from two pyrazolyl rings attached to the central carbon atom; the third pyrazolyl attached to carbon rotates forward like a scorpion's tail to "sting" the metal; hence the name of "scorpionates" (Figure 4).…”