Ring-Opening Polymerization of THF by Aryloxo-Modified (Imido)vanadium(V)-alkyl Complexes and Ring-Opening Metathesis Polymerization by Highly Active V(CHSiMe₃)(NAd)(OC₆F₅)(PMe₃)₂

Ring-opening polymerizations of THF using V­(NR)­(CH₂SiMe₃)­(OAr)₂ [R = 2,6-Me₂C₆H₃, 1-adamantyl (Ad), Ph; Ar = 2,6-Me₂C₆H₃, C₆F₅] proceeded in a living manner in the presence of [Ph₃C]­[B­(C₆F₅)₄], affording high molecular weight polymers with low PDI (<i>M</i>_w/<i>M</i>_n) values: the observed activity (initiation efficiency) was affected by the arylimido and aryloxo ligands employed. A new vanadium­(V)-alkylidene, V­(CHSiMe₃)­(NAd)­(OC₆F₅)­(PMe₃)₂, prepared from V­(NAd)­(CH₂SiMe₃)₂(OC₆F₅) by α-hydrogen elimination in <i>n</i>-hexane in the presence of PMe₃ at 25 °C, exhibited remarkable catalytic activity for ring-opening metathesis polymerization of norbornene: the activity at 25 °C was higher than those by the reported vanadium­(V)-alkylidenes and ordinary Mo­(CHCMe₂Ph)­(N-2,6-^<i>i</i>Pr₂-C₆H₃)­(O^<i>t</i>Bu)₂

Effect of Terminal Aryloxo Ligands in Ethylene Polymerization Using Titanatranes of the Type, [Ti(OAr){(O-2,4‑R₂C₆H₂)‑6-CH₂}₃N]: Synthesis and Structural Analysis of the Heterobimetallic Complexes of Titanatranes with AlMe₃

Effects of aryloxo terminal ligands and AlMe₃ in ethylene polymerization using a series of Ti­(OAr)­[{(O-2,4-R₂C₆H₂)-6-CH₂}₃N] [R = Me (<b>1</b>), ^<i>t</i>Bu (<b>2</b>); Ar = 2,6-Me₂C₆H₃ (<b>a</b>), 2,6-^<i>i</i>Pr₂C₆H₃ (<b>b</b>), 2,6-Ph₂C₆H₃ (<b>c</b>), 2,6-F₂C₆H₃ (<b>d</b>), C₆F₅ (<b>e</b>)] (<b>1a</b>–<b>1e</b>, <b>2d</b>,<b>2e</b>) in the presence of methylaluminoxane (MAO) have been explored. Reactions of <b>1b</b>,<b>1d</b>,<b>1e</b>, which showed an increase in the activity upon addition of a small amount of AlMe₃, with 1.0 equiv of AlMe₃ afforded heterobimetallic Ti–Al complexes, TiMe­(O-2,6-^<i>i</i>Pr₂C₆H₃)­[(O-2,4-Me₂C₆H₂-6-CH₂)­(μ₂-O-2,4-Me₂C₆H₂-6-CH₂)­(Me₂Al-μ₂-O-2,4-Me₂C₆H₂-6-CH₂)­N] (<b>3b</b>) and [TiMe­{(O-2,4-Me₂C₆H₂-6-CH₂)₂(μ₂-O-2,4-Me₂C₆H₂-6-CH₂)­N}]­[Me₂Al­(μ₂-OAr)] [Ar = 2,6-F₂C₆H₃ (<b>3d</b>), C₆F₅ (<b>3e</b>)], in moderate yields, and their structures were determined by X-ray crystallography. In contrast, the similar reaction of <b>1a</b> (which showed a decrease in the activity upon addition of AlMe₃) yielded [Al­(μ₂-O-2,6-C₆H₃)­Me₂]₂ and TiMe­[{(O-2,4-Me₂C₆H₂)-6-CH₂}₃N] as isolated forms: [Al­(μ₂-OC₆F₅)­Me₂]₂ was isolated from the mixture in the reactions of <b>1c</b>,<b>2d</b>,<b>2e</b>. The isolated heterobimetallic complexes (<b>3b</b>,<b>3d</b>,<b>3e</b>) exhibited high catalytic activities for ethylene polymerization in the presence of MAO, suggesting that these bimetallic species play a role in this catalysis

Effect of Terminal Aryloxo Ligands in Ethylene Polymerization Using Titanatranes of the Type, [Ti(OAr){(O-2,4‑R₂C₆H₂)‑6-CH₂}₃N]: Synthesis and Structural Analysis of the Heterobimetallic Complexes of Titanatranes with AlMe₃

Effects of aryloxo terminal ligands and AlMe₃ in ethylene polymerization using a series of Ti­(OAr)­[{(O-2,4-R₂C₆H₂)-6-CH₂}₃N] [R = Me (<b>1</b>), ^<i>t</i>Bu (<b>2</b>); Ar = 2,6-Me₂C₆H₃ (<b>a</b>), 2,6-^<i>i</i>Pr₂C₆H₃ (<b>b</b>), 2,6-Ph₂C₆H₃ (<b>c</b>), 2,6-F₂C₆H₃ (<b>d</b>), C₆F₅ (<b>e</b>)] (<b>1a</b>–<b>1e</b>, <b>2d</b>,<b>2e</b>) in the presence of methylaluminoxane (MAO) have been explored. Reactions of <b>1b</b>,<b>1d</b>,<b>1e</b>, which showed an increase in the activity upon addition of a small amount of AlMe₃, with 1.0 equiv of AlMe₃ afforded heterobimetallic Ti–Al complexes, TiMe­(O-2,6-^<i>i</i>Pr₂C₆H₃)­[(O-2,4-Me₂C₆H₂-6-CH₂)­(μ₂-O-2,4-Me₂C₆H₂-6-CH₂)­(Me₂Al-μ₂-O-2,4-Me₂C₆H₂-6-CH₂)­N] (<b>3b</b>) and [TiMe­{(O-2,4-Me₂C₆H₂-6-CH₂)₂(μ₂-O-2,4-Me₂C₆H₂-6-CH₂)­N}]­[Me₂Al­(μ₂-OAr)] [Ar = 2,6-F₂C₆H₃ (<b>3d</b>), C₆F₅ (<b>3e</b>)], in moderate yields, and their structures were determined by X-ray crystallography. In contrast, the similar reaction of <b>1a</b> (which showed a decrease in the activity upon addition of AlMe₃) yielded [Al­(μ₂-O-2,6-C₆H₃)­Me₂]₂ and TiMe­[{(O-2,4-Me₂C₆H₂)-6-CH₂}₃N] as isolated forms: [Al­(μ₂-OC₆F₅)­Me₂]₂ was isolated from the mixture in the reactions of <b>1c</b>,<b>2d</b>,<b>2e</b>. The isolated heterobimetallic complexes (<b>3b</b>,<b>3d</b>,<b>3e</b>) exhibited high catalytic activities for ethylene polymerization in the presence of MAO, suggesting that these bimetallic species play a role in this catalysis

Synthesis and Structural Analysis of (Imido)Vanadium(V) Complexes Containing Chelate (Anilido)Methyl-imine Ligands: Ligand Effect in Ethylene Dimerization

A series of (imido)vanadium dichlorido complexes containing chelate anionic donor ligands of the type, VCl₂(L)­(NR) [R = 1-adamantyl (Ad), L = 2-(2,6-Me₂C₆H₃)­NCH₂(C₉H₆N) (<b>2</b>), 8-(2,6-Me₂C₆H₃)­NCH₂(C₉H₆N) (<b>3</b>); L = 2-(2,6-R′₂C₆H₃)­NCH₂(C₅H₄N), R = 2-MeC₆H₄, R′ = Me (<b>4a</b>), ^<i>i</i>Pr (<b>4b</b>); L = 2-(2,6-Me₂C₆H₃)­NCH₂(C₅H₄N), R = 4-MeC₆H₄ (<b>5</b>), 3,5-Me₂C₆H₃ (<b>6</b>)], have been prepared and identified. The reactions with ethylene by <b>2</b>,<b>3</b> in the presence of methylaluminoxane (MAO) afforded a mixture of high molecular weight polyethylene and oligomers. Reactions with ethylene by VCl₂[2-(2,6-R′₂C₆H₃)­NCH₂(C₅H₄N)]­(NAd) (<b>1a,b</b>), <b>4</b>–<b>6</b> afforded 1-butene with high selectivities (>92%), and the activities by <b>4a</b>,<b>b</b> are at the same level as those in <b>1a</b>,<b>b</b>. The activities by <b>5</b>,<b>6</b> were lower than <b>4a</b>,<b>b</b> and were at the same level of that by VCl₂[2-(2,6-Me₂C₆H₃)­NCH₂(C₅H₄N)]­(NPh). These results thus suggest that both the chelate anionic donor and the imido ligands play a role for both the activity and the selectivity

Synthesis and Structural Analysis of (Imido)Vanadium(V) Complexes Containing Chelate (Anilido)Methyl-imine Ligands: Ligand Effect in Ethylene Dimerization

A series of (imido)vanadium dichlorido complexes containing chelate anionic donor ligands of the type, VCl₂(L)­(NR) [R = 1-adamantyl (Ad), L = 2-(2,6-Me₂C₆H₃)­NCH₂(C₉H₆N) (<b>2</b>), 8-(2,6-Me₂C₆H₃)­NCH₂(C₉H₆N) (<b>3</b>); L = 2-(2,6-R′₂C₆H₃)­NCH₂(C₅H₄N), R = 2-MeC₆H₄, R′ = Me (<b>4a</b>), ^<i>i</i>Pr (<b>4b</b>); L = 2-(2,6-Me₂C₆H₃)­NCH₂(C₅H₄N), R = 4-MeC₆H₄ (<b>5</b>), 3,5-Me₂C₆H₃ (<b>6</b>)], have been prepared and identified. The reactions with ethylene by <b>2</b>,<b>3</b> in the presence of methylaluminoxane (MAO) afforded a mixture of high molecular weight polyethylene and oligomers. Reactions with ethylene by VCl₂[2-(2,6-R′₂C₆H₃)­NCH₂(C₅H₄N)]­(NAd) (<b>1a,b</b>), <b>4</b>–<b>6</b> afforded 1-butene with high selectivities (>92%), and the activities by <b>4a</b>,<b>b</b> are at the same level as those in <b>1a</b>,<b>b</b>. The activities by <b>5</b>,<b>6</b> were lower than <b>4a</b>,<b>b</b> and were at the same level of that by VCl₂[2-(2,6-Me₂C₆H₃)­NCH₂(C₅H₄N)]­(NPh). These results thus suggest that both the chelate anionic donor and the imido ligands play a role for both the activity and the selectivity

Electrochemistry, Charge Transfer Properties, and Theoretical Investigation of a Macrocyclic Boronate Dimer of 1′,1‴-Biferrocenediboronic Acid and Related Ferrocenyl Boronate Complexes

The target compound of this study is the macrocyclic tetraferrocenyl boronate complex <b>CP</b>_<b>2</b><b>C</b>, which has two types of metal connections (i.e., Fe^II–CpCp–Fe^II and Fe^II–CpBO₂C₅H₈O₂BCp–Fe^II (Cp = cyclopentadienyl)) in the finite structure (<b>C</b> = 1′,1‴-biferrocenediboronic acid, <b>P</b> = pentaerythritol). The electrochemical behavior of <b>CP</b>_<b>2</b><b>C</b> in dichloromethane was compared with that of the related boronate complexes <b>APA</b> and <b>BP</b>_<b>2</b><b>B</b>, having Fe^II–CpBO₂C₅H₈O₂BCp–Fe^II, and <b>Cester</b>, having Fe^II–CpCp–Fe^II. The effects of the counteranion of the supporting electrolyte on potential splitting revealed that <b>CP</b>_<b>2</b><b>C</b> exhibits an intrabiferrocenyl through-bond interaction through the CpCp ligand, as well as an interbiferrocenyl through-space interaction across the CpBO₂C₅H₈O₂BCp ligand. Chemical oxidation of <b>CP</b>_<b>2</b><b>C</b> with AgSbF₆ produced the one- and two-electron-oxidized species <b>CP</b>_<b>2</b><b>C</b>^<b>+</b> and <b>CP</b>_<b>2</b><b>C</b>^<b>2+</b>, which exhibit intervalence charge transfer transition bands through the CpCp ligand in the near-infrared region, giving one and two valence isomers, respectively. DFT calculations revealed the charge distribution of <b>CP</b>_<b>2</b><b>C</b>^<b>2+</b>; the positive charges are localized on each biferrocenium unit, especially on the longer diagonal, to minimize the electrostatic repulsion over the CpBO₂C₅H₈O₂BCp ligand

Electrochemistry, Charge Transfer Properties, and Theoretical Investigation of a Macrocyclic Boronate Dimer of 1′,1‴-Biferrocenediboronic Acid and Related Ferrocenyl Boronate Complexes

The target compound of this study is the macrocyclic tetraferrocenyl boronate complex <b>CP</b>_<b>2</b><b>C</b>, which has two types of metal connections (i.e., Fe^II–CpCp–Fe^II and Fe^II–CpBO₂C₅H₈O₂BCp–Fe^II (Cp = cyclopentadienyl)) in the finite structure (<b>C</b> = 1′,1‴-biferrocenediboronic acid, <b>P</b> = pentaerythritol). The electrochemical behavior of <b>CP</b>_<b>2</b><b>C</b> in dichloromethane was compared with that of the related boronate complexes <b>APA</b> and <b>BP</b>_<b>2</b><b>B</b>, having Fe^II–CpBO₂C₅H₈O₂BCp–Fe^II, and <b>Cester</b>, having Fe^II–CpCp–Fe^II. The effects of the counteranion of the supporting electrolyte on potential splitting revealed that <b>CP</b>_<b>2</b><b>C</b> exhibits an intrabiferrocenyl through-bond interaction through the CpCp ligand, as well as an interbiferrocenyl through-space interaction across the CpBO₂C₅H₈O₂BCp ligand. Chemical oxidation of <b>CP</b>_<b>2</b><b>C</b> with AgSbF₆ produced the one- and two-electron-oxidized species <b>CP</b>_<b>2</b><b>C</b>^<b>+</b> and <b>CP</b>_<b>2</b><b>C</b>^<b>2+</b>, which exhibit intervalence charge transfer transition bands through the CpCp ligand in the near-infrared region, giving one and two valence isomers, respectively. DFT calculations revealed the charge distribution of <b>CP</b>_<b>2</b><b>C</b>^<b>2+</b>; the positive charges are localized on each biferrocenium unit, especially on the longer diagonal, to minimize the electrostatic repulsion over the CpBO₂C₅H₈O₂BCp ligand

Electrochemistry, Charge Transfer Properties, and Theoretical Investigation of a Macrocyclic Boronate Dimer of 1′,1‴-Biferrocenediboronic Acid and Related Ferrocenyl Boronate Complexes

The target compound of this study is the macrocyclic tetraferrocenyl boronate complex <b>CP</b>_<b>2</b><b>C</b>, which has two types of metal connections (i.e., Fe^II–CpCp–Fe^II and Fe^II–CpBO₂C₅H₈O₂BCp–Fe^II (Cp = cyclopentadienyl)) in the finite structure (<b>C</b> = 1′,1‴-biferrocenediboronic acid, <b>P</b> = pentaerythritol). The electrochemical behavior of <b>CP</b>_<b>2</b><b>C</b> in dichloromethane was compared with that of the related boronate complexes <b>APA</b> and <b>BP</b>_<b>2</b><b>B</b>, having Fe^II–CpBO₂C₅H₈O₂BCp–Fe^II, and <b>Cester</b>, having Fe^II–CpCp–Fe^II. The effects of the counteranion of the supporting electrolyte on potential splitting revealed that <b>CP</b>_<b>2</b><b>C</b> exhibits an intrabiferrocenyl through-bond interaction through the CpCp ligand, as well as an interbiferrocenyl through-space interaction across the CpBO₂C₅H₈O₂BCp ligand. Chemical oxidation of <b>CP</b>_<b>2</b><b>C</b> with AgSbF₆ produced the one- and two-electron-oxidized species <b>CP</b>_<b>2</b><b>C</b>^<b>+</b> and <b>CP</b>_<b>2</b><b>C</b>^<b>2+</b>, which exhibit intervalence charge transfer transition bands through the CpCp ligand in the near-infrared region, giving one and two valence isomers, respectively. DFT calculations revealed the charge distribution of <b>CP</b>_<b>2</b><b>C</b>^<b>2+</b>; the positive charges are localized on each biferrocenium unit, especially on the longer diagonal, to minimize the electrostatic repulsion over the CpBO₂C₅H₈O₂BCp ligand

Conglomerate, Racemate, and Achiral Crystals of Polymetallic Europium(III) Compounds of Bis- or Tris-β-diketonate Ligands and Circularly Polarized Luminescence Study

This work reports (a) conglomerate and racemic crystal structures of [(Δ,Δ,Δ,Δ,Δ,Δ)- or/and (Λ,Λ,Λ,Λ,Λ,Λ)-EuIII6(TTP)8(OH2)6Na4]n coordination polymers, (b) racemic crystal structures of (Δ,Δ,Δ,Δ)-/(Λ,Λ,Λ,Λ)-EuIII4(TTP)4(bipy)4(MEK)2(OH2)2 tetrahedral clusters, and (c) the achiral crystal structure of the [EuIII2(BTP)4(OH2)2Na2]n coordination polymer (where BTP = dianionic bis-β-diketonate, TTP = trianionic tris-β-diketonate, and bipy = 2,2′-bipyridine). The screw coordination arrangement of the TTP ligand has led to the formation of homoconfigurational racemic EuIII products. The conglomerate crystallization of [EuIII6(TTP)8(OH2)6Na4]n appears to be caused by the presence of the sodium, Na+ counterions, and interactions between oxygen atoms and the trifluoromethyl unit of the TTP ligand and Na+ ions. All the EuIII compounds exhibit characteristic red luminescence (5D0 → 7FJ, J = 0–4) in solution or in the solid crystalline state. Circularly polarized luminescence (CPL) was observed in the chiral EuIII6(TTP)8(OH2)6Na4]n species, displaying a |glum| value in the range of 0.15 to 0.68 at the 5D0 → 7F1 emission band. Subtle changes of the [EuIII6(TTP)8(OH2)6Na4]n structure which may be due to selection of twinned crystals or crystals that do not correspond to a perfect spontaneous resolution, are considered to be responsible for the variation in the observed CPL values

Excited State Engineering in Ag₂₉ Nanocluster through Peripheral Modification with Silver(I) Complexes for Bright Near-Infrared Photoluminescence

The optical property of an ionic metal nanocluster (NC) is affected by the ionic interaction with counter ions. Here, we report that the modification of trianionic [Ag29(BDT)12(TPP)4]3– NC (BDT: 1.3-benzenedithiol; TPP: triphenylphosphine) with silver(I) complexes led to the intense photoluminescence (PL) in the near-infrared (NIR) region. The binding of silver(I) complexes to the peripheral region of Ag29 NC is confirmed by the single-crystal X-ray diffraction (SCXRD) measurement, which is further supported by electrospray ionization mass spectrometry (ESI-MS) and nuclear magnetic resonance (NMR) spectroscopy. The change of excited-state dynamics by the binding of silver(I) complexes is discussed based on the results of a transient absorption study as well as temperature-dependent PL spectra and PL lifetime measurements. The modification of Ag29 NCs with cationic silver(I) complexes is considered to give rise to a triplet excited state responsible for the intense NIR PL. These findings also afford important insights into the origin of the PL mechanism as well as the possible light-driven motion in Ag29-based NCs