112362-30-8Relevant articles and documents
New Iron(II) Spin-crossover Complexes with Heterocyclic Amine-derived Ligands and STEPS Experiments on Photogenerated Metastable High-spin States
Addison, Anthony W.,Burman, Sudhir,Wahlgren, Curtis G.,Rajan, Odatt A.,Rowe, Teresa M.,Sinn, Ekkehard
, p. 2621 - 2630 (1987)
Cationic complexes of the type NN)3>2+ and NNN)2>2+ have been isolated as Cl-, ClO4-, or BF4- salts, where LNN and LNNN represent bidentate and tridentate nitrogen-donor ligands respectively.The bidentate ligands were 2-(2'pyridyl)benzimidazole (pybzim), 2-(2'-pyridyl)-N-methylbenzimidazole (mpybzim); 2-(2'-pyridyl)benzothiazole (pybzt), 2,2'-dipyridylamine (dpya), and the tridentates di(2-pyridylmethyl)amine (dpyma), 2,6-bis(benzimidazol-2'-yl)pyridine (bzimpy), 2,6-bis(N-methylbenzimidazol-2'-yl)pyridine (mbzimpy), and 2,6-bis(benzothiazol-2'-yl)pyridine (bztpy).Except for , all these FeN6 chromophores exhibit strong absorption in the 550 nm region, which is assigned as a metal-to-ligand charge-transfer transition.Between 4 and 320 K, the iron(II) is in the low-spin form in the majority of these compounds; high-spin exceptions are 2 and Cl2.Other complexes show evidence of the onset of a spin transition near 40 deg C, while the salt *CHCl3 is a well defined spin-crossover system.The low-spin complex 2 was excited by irradiation with visible light, and the generation and decay of resulting high-spin form was observed under cryogenic conditions.In solution, 2+ acts as a weak diprotic acid and also exhibits quintet ->/o = -42.7 kJmol-1, ΔSo = -140.9 JK-1mol-1).The complexes are all electrochemically oxidizable to their iron(III) forms in non-aqueous solution, but the dpyma, bztpy, pybtz, and dpya chelates thus formed are unstable.The iron(III) complex -2bzimpy)2>- containing the doubly deprotonated ligand was obtained as its low-spin triethylammonium salt.The high-spin chloro complexes . , Fe(mbzimpy)Cl2, and the mixed-spin iron(II) complex salt were also isolated.
N3-Ligated nickel(ii) diketonate complexes: synthesis, characterization and evaluation of O2reactivity
Berreau, Lisa M.,Elsberg, Josiah G. D.,Fuller, Amy L.,Peterson, Austin
, p. 7564 - 7575 (2020)
Interest in O2-dependent aliphatic carbon-carbon (C-C) bond cleavage reactions of first row divalent metal diketonate complexes stems from the desire to further understand the reaction pathways of enzymes such as DKE1 and to extract information to develop applications in organic synthesis. A recent report of O2-dependent aliphatic C-C bond cleavage at ambient temperature in Ni(ii) diketonate complexes supported by a tridentate nitrogen donor ligand [(MBBP)Ni(PhC(O)CHC(O)Ph)]Cl (7-Cl; MBBP = 2,6-bis(1-methylbenzimidazol-2-yl)pyridine) in the presence of NEt3spurred our interest in further examining the chemistry of such complexes. A series of new TERPY-ligated Ni(ii) diketonate complexes of the general formula [(TERPY)Ni(R2-1,3-diketonate)]ClO4(1: R = CH3;2: R = C(CH3)3;3: R = Ph) was preparedunder airand characterized using single crystal X-ray crystallography, elemental analysis,1H NMR, ESI-MS, FTIR, and UV-vis. Analysis of the reaction mixtures in which these complexes were generated using1H NMR and ESI-MS revealed the presence of both the desired diketonate complex and the bis-TERPY derivative [(TERPY)2Ni](ClO4)2(4). Through selective crystallization1-3were isolated in analytically pure form. Analysis of reaction mixtures leading to the formation of the MBBP analogs [(MBBP)Ni(R2-1,3-diketonate)]X (X = ClO4:5: R = CH3;6: R = C(CH3)3;7-ClO4: R = Ph; X = Cl:7-Cl: R = Ph) using1H NMR and ESI-MS revealed the presence of [(MBBP)2Ni](ClO4)2(8). Analysis of aerobic acetonitrile solutions of analytically pure1-3,5and6containing NEt3and in some cases H2O using1H NMR and UV-vis revealed evidence for the formation of additional bis-ligand complexes (4and8) but suggested no oxidative diketonate cleavage reactivity. Analysis of the organic products generated from3,7-ClO4and7-Clrevealed unaltered dibenzoylmethane. Our results therefore indicate that N3-ligated Ni(ii) complexes of unsubstituted diketonate ligands do not exhibit O2-dependent aliphatic C-C bond clevage at room temperature, including in the presence of NEt3and/or H2O.
Solution aggregation of platinum(ii) triimine methyl complexes
Connick, William B.,Shingade, Vikas M.
, p. 10729 - 10733 (2020)
The NMR chemical shifts of [Pt(tpy)(CH3)](PF6) (1) and [Pt(mbzimpy)(CH3)](PF6) (2), where tpy = 2,2′;6′2′′-terpyridine and mbzimpy = 2,6-bis(N-methylbenzimidazol-2-yl)pyridine, in room-temperature DMSO-d6 displayed concentration dependence as a result of formation of dimers. Quantification of these dimers, expressed by equilibrium constant (K), shows a greater tendency of 2 to aggregate in solution. Structural conformations of these dimers were confirmed by 2D 1H-1H NOESY; the results explicitly suggest a head-to-tail stacking arrangement of molecules in dimers. This journal is
Tuning of redox potentials by introducing a cyclometalated bond to bis-tridentate ruthenium(II) complexes bearing bis(N -methylbenzimidazolyl) benzene or -pyridine ligands
Yang, Wen-Wen,Zhong, Yu-Wu,Yoshikawa, Shinpei,Shao, Jiang-Yang,Masaoka, Shigeyuki,Sakai, Ken,Yao, Jiannian,Haga, Masa-Aki
, p. 890 - 899 (2012)
A series of asymmetrical bis-tridentate cyclometalated complexes including [Ru(Mebib)(Mebip)]+, [Ru(Mebip)(dpb)]+, [Ru(Mebip)(Medpb)]+, and [Ru(Mebib)(tpy)]+ and two bis-tridentate noncyclometalated complexes [Ru(Mebip)2]2+ and [Ru(Mebip)(tpy)]2+ were prepared and characterized, where Mebib is bis(N-methylbenzimidazolyl)benzene, Mebip is bis(N-methylbenzimidazolyl) pyridine, dpb is 1,3-di-2-pyridylbenzene, Medpb is 4,6-dimethyl-1,3-di-2- pyridylbenzene, and tpy is 2,2′:6′,2″-terpyridine. The solid-state structure of [Ru(Mebip)(Medpb)]+ is studied by X-ray crystallographic analysis. The electrochemical and spectroscopic properties of these ruthenium complexes were studied and compared with those of known complexes [Ru(tpy)(dpb)]+ and [Ru(tpy)2]2+. The change of the supporting ligands and coordination environment allows progressive modulation of the metal-associated redox potentials (Ru II/III) from +0.26 to +1.32 V vs Ag/AgCl. The introduction of a ruthenium cyclometalated bond in these complexes results in a significant negative potential shift. The RuII/III potentials of these complexes were analyzed on the basis of Lever's electrochemical parameters (E L). Density functional theory (DFT) and time-dependent DFT calculations were carried out to elucidate the electronic structures and spectroscopic spectra of complexes with Mebib or Mebip ligands.
Luminescent Pt(2,6-bis(: N -methylbenzimidazol-2-yl)pyridine)X+: A comparison with the spectroscopic and electrochemical properties of Pt(tpy)X+(X = Cl, CCPh, Ph, or CH3)
Connick, William B.,Grove, Levi J.,Shingade, Vikas M.
supporting information, p. 9651 - 9661 (2020/07/30)
A series of platinum(ii) pincer complexes of the formula Pt(mbzimpy)X+, 1(a-d), (mbzimpy = 2,6-bis(N-methylbenzimidazol-2-yl)pyridine; X = Cl; (a), CCPh; (b), Ph; (c), or CH3; (d), CCPh = phenylacetylide, and Ph = Phenyl) have been synthesized and characterized. Electronic absorption and emission, as well as electrochemical properties of these compounds, have been investigated. Pt(tpy)X+ analogs (tpy = 2,2′;6′2′′-terpyridine), 2(a-d), have also been investigated and compared. Electrochemistry shows that 1 and 2 analogs undergo two chemically reversible one-electron reduction processes that are shifted cathodically along the a b c d series. Notably, these reductions occur at slightly higher negative potentials in the case of 1. The absorption spectra of 1 and 2 in acetonitrile exhibit ligand-centered (1LC) transitions (? ≈ 104 M-1 cm-1) in the UV region and metal-to-ligand-charge transfer (1MLCT) transitions (? ≈ 103 M-1 cm-1) in the visible region. The corresponding visible bands of 1b and 2b have been assigned to 1(LLCT/MLCT) mixed state (LLCT: ligand-to-ligand-charge transfer). The preceding 1LC and 1MLCT transitions of 1 occur at lower energies than that of 2. These 1LC transitions have distinctly been blue-shifted along a c d in 2, but occur at nearly identical energies in 1. Conversely, 1MLCT transitions are red-shifted along a c d in both the analogs. The 77 K glassy solutions of 1 and 2 exhibit an intense vibronically-structured emission band at λmax(0-0) in the 470-560 nm range. This band is red-shifted along b a ≤ c d in 1 and along a ≤ d ≈ c ? b in 2. The main character of these emissions is assigned to 3LLCT emissive state in 1b and 2b, whereas to 3LC in the rest of the compounds. Relative stabilization of these spin-forbidden emissive states is discussed by invoking configuration mixing with the higher-lying 3MLCT state.
