cis-Dioxomolybdenum(VI) complexes of sterically encumbered phenol-based tetradentate N2O2 ligands: Structural, spectroscopic, and electrochemical studies

Abstract

Two cis-dioxomolybdenum(VI) complexes [MoO 2 L] (L: L 1 , 2 and L: L 2 , 3) in a phenol-based sterically encumbered N 2 O 2 ligand environment have been synthesized, and their crystallographic characterizations are reported. The orange crystals of 2 are monoclinic, space group P2 1 /a with unit cell dimensions as a = 16.2407(17) Å, b = 7.2857(8) Å, c = 18.400(2) Å, β = 98.002(9) • , Z = 4, and d cal = 1.486 g cm −3 . The light orange crystals of 3, however, are orthorhombic, space group, Pbcn, with unit cell dimensions a = 8.3110(12) Å, b = 12.637(3) Å, c = 34.673(5) Å, Z = 4, and d cal = 1.187 g cm −3. The structures were refined by a full-matrix least-squares procedure on F 2 to a final R = 0.046 (0.055 for 3) using 4944 (3677) all independent data. In both the cases, the Mo atom exists in a distorted octahedral geometry defined by a N 2 O 4 donor set, which features a cis-Mo(=O) 2 and a trans-Mo(OPh) 2 arrangement. Compound 2 undergoes a quasireversible one-electron reduction at −1.3 V vs Ag/AgCl reference due to Mo VI O 2 /Mo V O 2 electron transfer and thus providing a rare example of steric solution to the comproportionation-dimerization problem encountered frequently in the development of valid biomimetic models for the active sites of oxomolybdenum enzymes.

Highly Stable Hexacoordinated Nonoxidovanadium(IV) Complexes of Sterically Constrained Ligands: Syntheses, Structure, and Study of Antiproliferative and Insulin Mimetic Activity

“…In the anodic region, complexes show a quasi-reversible single electron wave (Figure a) at E 1/2 values within the potential window of 1.11 to 1.09 V, which is assigned to the oxidation of the metal, V(IV)/V(V) . In the cathodic region, V(IV) is reduced to V(III), which shows a quasi-reversible single electron wave (Figure b) at E 1/2 values within the potential window of −0.55 to −0.53 V …”

Biomimetic Oxidative Bromination by cis‐Dioxidotungsten(VI) Complexes of Salan Type N,N’‐Capped Linear Tetradentate Amino Bisphenol

“…Upon metal complex formation H 2 salan, being more flexible than H 2 salen and having better N‐basicity, may lead to different structural conformation which may affect on the catalytic activity of different substrates and selectivity of the product(s) [14–16] . Considering the location of oxygen atoms ( Ax , Eq ) of cis ‐[MO 2 ] (M=V, Mo and W) complexes, and positions of O and N atoms of such flexible tetradentate ligands in octahedral environment, three different isomeric structures are possible: (i) α‐ cis , symmetric (a), (ii) β‐ cis , asymmetric (b), and (iii) β‐ cis , asymmetric (c) (Scheme 1).…”

DNA/BSA binding interactions and VHPO mimicking potential of vanadium(IV) complexes: Synthesis, structural characterization and DFT studies

“…The VOL 1 ‐VOL 3 shows a quasi‐reversible single electron wave at the potential range of ~ − 0.621 V, which is assigned to the reduction of V(IV) to V(III). The corresponding oxidation process occurs in the potential of ~ − 0.48 V …”

“…The VOL 1 -VOL 3 shows a quasi-reversible single electron wave at the potential range of~− 0.621 V, which is assigned to the reduction of V(IV) to V(III). The corresponding oxidation process occurs in the potential of~− 0.48 V. [34] Electronic absorption spectral titration method was employed to find out the binding interaction of VOL 1 -VOL 3 with DNA. Metal complexes bind to DNA by intercalation are distinguished by the change in absorbance and bathochromic shift in wavelength.…”