Syntheses, structures and bonding of 3d metal alkynyl complexes of cyclam and its derivatives

Banziger, Susannah D.; Ren, Tong

doi:10.1016/j.jorganchem.2019.01.024

Cited by 19 publications

(36 citation statements)

References 106 publications

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“…30−33 With the desire to use more earth-abundant elements and cost-efficient resources, our recent efforts have focused on cyclam complexes of 3d transition metals (cyclam = 1,4,8,11tetraazacyclotetradecane). Our work, 34,35 along with those from the laboratories of Shores, 36,37 Nishijo, 38−42 and Wagenknecht, 43−48 has significantly expanded the scope of this previously underexplored field. While previous work on dicobalt species bridged by oligoynes revealed the structural features similar to highly delocalized Ru 2 compounds, their voltammetric responses were not ideal.…”

Section: ■ Introductionmentioning

confidence: 91%

Improving Redox Reversibility and Intermetallic Coupling of Co(III) Alkynyls through Tuning of Frontier Orbitals

2020

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Reported herein are the syntheses and characterizations for a series of butadiyndiyl-bridged Co III (MPC) (MPC = 5,4,8, complexes, capped with chloride ([1] 2+ ), phenylacetylide ([2] 2+ ), or 3,5-dichlorophenylacetylide ([3] 2+ ). The MPC ligand was chosen to weaken the ligand field around the equatorial plane, allowing stronger axial coordination. Cyclic voltammetry measurement revealed the first unambiguous examples of stepwise one-electron reductions in bridged Co(cyclam′) complexes (cyclam′ = any ligand bearing the 1,4,8,11-tetraazacyclotetradecane framework). Further voltammetric analysis using NBu 4 BArF (NBu 4 BArF = tetrabutylammonium tetrakis [3,5-bis(trifluoromethyl)phenyl]borate) as electrolyte resulted in well-separated reversible reduction waves with up to 160 mV separation for [2] 2+ . These features hint at the possibility of application of earth-abundant metal complexes to function as molecular wires. These complexes were also characterized with infrared and UV−vis spectroscopy, density functional theory calculations, and single-crystal X-ray diffraction ([1](BPh 4 ) 2 only).

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Section: ■ Introductionmentioning

confidence: 91%

Improving Redox Reversibility and Intermetallic Coupling of Co(III) Alkynyls through Tuning of Frontier Orbitals

2020

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“…Our laboratory has become interested in 3d metal alkynyl compounds supported by both cyclam (1,4,8,11-tetraazacyclotetradecane) and its C-substituted derivatives. , Though the area is fairly young, Co(cyclam)-based compounds have been a frequent target due to the possibility of high yield preparation of trans -[Co(cyclam)(C 2 R)Cl] + under mild conditions. − Recent efforts led to the preparation of [Co(cyclam)(C 2 NAP R )Cl]Cl (NAP R = N -R-1,8-naphthalimide with R as isopropyl, NAP iPr , and mesityl, NAP Mes ) with a focus on the NAP R moiety as an emissive electron acceptor. , Explored in this study are the [Co(cyclam)(C 2 TPA)Cl] + and [Co(cyclam)(C 2 TPA) 2 ] + type compounds with HC 2 TPA as 4-ethynyl- N,N -bis(4-methoxyphenyl)aniline. Triarylamines (Ar 3 N) are excellent electron donors and exhibit a reversible one-electron oxidation that is accompanied by drastic changes in electronic absorption spectra, the latter of which has been frequently exploited in probing both organic − and organometallic mixed valency through spectroelectrochemical investigation .…”

Section: Introductionmentioning

confidence: 99%

Co(cyclam) Complexes of Triarylamine-acetylide: Structural and Spectroscopic Properties and DFT Analysis

et al. 2020

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Reported herein are the syntheses of mono-and bis-C 2 TPA (HC 2 TPA = 4-ethynyl-N,N-bis(4-methoxyphenyl)aniline) complexes of Co III (cyclam) (cyclam = 1,4,8,11-tetraazacyclotetradecane) complexes, and the formation of η 2 -adducts of Cu(I)/Ag(I) to the acetylenic bond of TPAC 2 ligand. The reaction between trans-[Co(cyclam)Cl 2 ]Cl and HC 2 TPA in the presence of Et 2 NH yielded trans-[Co(cyclam)(C 2 TPA)Cl]Cl ([1]Cl) and subsequent treatment of [1]Cl with CuCl or AgNO 3 afforded trans-[Co(cyclam)(C 2 TPAη 2 -CuCl 2 )Cl] (2a) or trans-[Co(cyclam)(C 2 TPA-η 2 -Ag(NO 3 ) 2 )(NO 3 )] (2b), respectively. The reaction between [Co(cyclam)Cl 2 ]Cl and 3 equiv of LiC 2 TPA afforded trans-[Co(cyclam)(C 2 TPA) 2 ]Cl ([3]Cl). X-ray diffraction studies of compounds [1]Cl, 2a/b, and [3]Cl established their molecular structures. All four compounds display redox couples that are characteristic of TPA (reversible oxidation) and Co III (irreversible reduction) center. The reversible TPA oxidation in compounds [1]Cl and [3]Cl enables further UV−vis/near-IR spectroelectrochemical studies to elucidate the change of electronic structures upon oxidation. The electronic spectra of both compounds [1]Cl and [3]Cl and their oxidized derivatives have been rationalized based on DFT and TD-DFT analysis.

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“…Synthesis of mono acetylide Co III (cyclam) compounds 1a – 1e was accomplished under N 2 through the reaction of HC 2 NAP R (R is defined in Scheme ) with [Co(cyclam)Cl 2 ]Cl in the presence of Et 3 N . Except for 1b , purification over silica resulted in bright orange microcrystalline solids in 45–63 % yield.…”

Section: Resultsmentioning

confidence: 99%

“…Each synthetic route suffers from harsh conditions, with the most notable being (i) use of a strong base and (ii) high temperature. Previous work to synthesize the first dissymmetric D‐B‐A Co III (cyclam) complexes, where D = C 6 H 4 ‐4‐NR′ 2 (R′ = Me or Ph‐4‐OMe) and A = N ‐isopropyl‐1,8‐naphthalimide (NAP i Pr), could only be accomplished using the first route . Since that time, our group has investigated the tuning of reactivity, crystallinity, and “robustness” of the naphthalimide unit through altering the alkyl group directly linked to the imide.…”

Section: Introductionmentioning

confidence: 99%

“…Each synthetic route suffers from harsh conditions, with the most notable being (i) use 1,8-naphthalimide (NAPiPr), could only be accomplished using the first route. [18] Since that time, our group has investigated the tuning of reactivity, crystallinity, and "robustness" of the naphthalimide unit through altering the alkyl group directly linked to the imide. Reported herein is the synthesis of new Co III (cyclam)(C 2 NAP R ) species with R as mesityl (Mes, 1a), methyl (Me, 1b), 1-ethylpropyl (Pen, 1c), 2-ethylhexyl (2-ethhex, 1d), or n-octyl (Oct, 1e) and a discussion on their properties and reactivity (Scheme 2).…”

Section: Introductionmentioning

confidence: 99%

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New Synthetic Route for Cobalt(III) Dissymmetric Bisalkynyl Complexes Based on Cobalt(III)(cyclam)(C₂NAP^Mes)

2019

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The synthesis and characterization of dissymmetric Co III -bis-alkynyl complexes supported by cyclam (1,4,8,11-tetraazacyclotetradecane) are reported. A series of trans-[Co(cyclam)-(C 2 NAP R )Cl]Cl were prepared from the reaction between [Co-(cyclam)Cl 2 ]Cl and HC 2 NAP R in the presence of Et 3 N, where NAP R is N-R-1,8-naphthalimide with R as mesityl (Mes, 1a), methyl (Me, 1b), 1-ethylpropyl (Pen, 1c), 2-ethylhexyl (2-ethhex, 1d), or noctyl (Oct, 1e). Treating compounds 1a and 1b with AgOTf in [a] Dr. 4766Scheme 3. i.) 3 equiv. H 2 NR, ethanol/2-propanol, reflux, 18-84 h; ii.) 2-3 equiv. HC 2 SiMe 3 , iPr 2 NH, 2 mol-% CuI, 2 mol-% Pd(PPh 3 ) 2 Cl 2 , 20 min-2 h; iii.) excess K 2 CO 3 , MeOH, 30 min.

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Syntheses, structures and bonding of 3d metal alkynyl complexes of cyclam and its derivatives

Cited by 19 publications

References 106 publications

Improving Redox Reversibility and Intermetallic Coupling of Co(III) Alkynyls through Tuning of Frontier Orbitals

Improving Redox Reversibility and Intermetallic Coupling of Co(III) Alkynyls through Tuning of Frontier Orbitals

Co(cyclam) Complexes of Triarylamine-acetylide: Structural and Spectroscopic Properties and DFT Analysis

New Synthetic Route for Cobalt(III) Dissymmetric Bisalkynyl Complexes Based on Cobalt(III)(cyclam)(C₂NAP^Mes)

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Syntheses, structures and bonding of 3d metal alkynyl complexes of cyclam and its derivatives

Cited by 19 publications

References 106 publications

Improving Redox Reversibility and Intermetallic Coupling of Co(III) Alkynyls through Tuning of Frontier Orbitals

Improving Redox Reversibility and Intermetallic Coupling of Co(III) Alkynyls through Tuning of Frontier Orbitals

Co(cyclam) Complexes of Triarylamine-acetylide: Structural and Spectroscopic Properties and DFT Analysis

New Synthetic Route for Cobalt(III) Dissymmetric Bisalkynyl Complexes Based on Cobalt(III)(cyclam)(C2NAPMes)

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New Synthetic Route for Cobalt(III) Dissymmetric Bisalkynyl Complexes Based on Cobalt(III)(cyclam)(C₂NAP^Mes)