Synthesis and Structure Analysis of α and β Forms of [12] Metallacrown-6 Nickel(II) Complex: [Ni6(SCH2CH2CH3)12]

Hai, Xiao; Jian, Fang Fang; Zhang, Ke Jie

doi:10.5012/bkcs.2009.30.4.846

Cited by 7 publications

(1 citation statement)

References 22 publications

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“…The organothiol PET ligands (not shown) extend from the S atoms to complete the Ni 6 (PET) 12 structure. The general Ni 6 (SR) 12 structure (SR = organothiol ligand) was first reported in 1965, and subsequent synthetic routes have produced Ni 6 (SR) 12 complexes containing a variety of different ligands. ,,− The persistence of this particular complex through different synthetic procedures and with various organic ligands indicates a robust atomic arrangement, and DFT studies have predicted Ni 6 (PET) 12 to be a very stable complex due to electron delocalization throughout ring structure. , However, reports on the catalytic applications of Ni 6 (SR) 12 remain scarce despite their rich synthetic history and predicted stability. , …”

Section: Resultsmentioning

confidence: 99%

Electrocatalytic Oxygen Evolution with an Atomically Precise Nickel Catalyst

et al. 2016

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The electrochemical oxygen evolution reaction (OER) is an important anodic process in water splitting and CO2 reduction applications. Precious metals including Ir, Ru. and Pt are traditional OER catalysts, but recent emphasis has been placed on finding less expensive, earth-abundant materials with high OER activity. Ni-based materials are promising next-generation OER catalysts because they show high reaction rates and good long-term stability. Unfortunately, most catalyst samples contain heterogeneous particle sizes and surface structures that produce a range of reaction rates and rate-determining steps. Here we use a combination of experimental and computational techniques to study the OER at a supported organometallic nickel complex with a precisely known crystal structure. The Ni6(PET)12 (PET = phenylethyl thiol) complex out performed bulk NiO and Pt and showed OER activity comparable to Ir. Density functional theory (DFT) analysis of electrochemical OER at a realistic Ni6(SCH3)12 model determined the Gibbs free energy change (ΔG) associated with each mechanistic step. This allowed computational prediction of potential determining steps and OER onset potentials that were in excellent agreement with experimentally determined values. Moreover, DFT found that small changes in adsorbate binding configuration can shift the potential determining step within the OER mechanism and drastically change onset potentials. Our work shows that atomically precise nanocatalysts like Ni6(PET)12 facilitate joint experimental and computational studies because experimentalists and theorists can study nearly identical systems. These types of efforts can identify atomic-level structure–property relationships that would be difficult to obtain with traditional heterogeneous catalyst samples.

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Section: Resultsmentioning

confidence: 99%

Electrocatalytic Oxygen Evolution with an Atomically Precise Nickel Catalyst

et al. 2016

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Synthesis and Structures of Cuprous Triptycylthiolate Complexes

2012

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A synthesis of 1-(thioacetyl)triptycene (5), a convenient protected form of 1-(thiolato)triptycene [STrip](-), is described, a key transformation being the high yield conversion of tert-butyl 1-triptycenyl sulfide (8) to 5 by a protocol employing BBr(3)/AcCl. Syntheses of the two-coordinate copper(I) compounds [Bu(4)N][Cu(STrip)(2)], [Bu(4)N]10, and [(Cu(IMes)(STrip)] (13) proceed readily by chloride displacement from CuCl and [Cu(IMes)Cl], respectively. Reaction of 10 with Ph(3)SiSH or Me(3)SiI produces the heteroleptic species [Cu(STrip)(SSiPh(3))](-) (11) and [Cu(STrip)I](-) (12), detected by mass spectrometry, in mixture with the homoleptic bis(thiolate) anions. Structural identification by X-ray crystallography of the ligand precursor molecules 9-(thioacetyl)anthracene (4, triclinic and orthorhombic polymorphs), tert-butyl 9-anthracenyl sulfide (7), 5, and tert-butyl 1-triptycenyl sulfide (8) are presented. Crystallographic characterization of bis(9-anthracenyl)sulfide (3), which features a C-S-C angle of 104.0° and twist angle of 54.8° between anthracenyl planes, is also given. A crystal structure of [Bu(4)N][(STrip)], [Bu(4)N]9, provides an experimental measure of 144.6° for the ligand cone angle. The crystal structures of [Bu(4)N]10 and 13 are reported, the former of which reveals an unexpectedly small C-S···S-C torsion angle of ∼41° (average of two values), which confers a near "cis" disposition of the triptycenyl groups with respect the S-Cu-S axis. This conformation is governed by interligand π···π and CH···π interactions. A crystal structure of an adventitious product, [Bu(4)N][(Cu-STrip)(6)(μ(6)-Br)]·[Bu(4)N][PF(6)], [Bu(4)N]14·[Bu(4)N][PF(6)] is described, which reveals a cyclic hexameric structure previously unobserved in cuprous thiolate chemistry. The Cu(6)S(6) ring displays a centrosymmetric cyclohexane chair type conformation with a Br(-) ion residing at the inversion center and held in place by apparent soft-soft interactions with the Cu(I) ions.

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Photocatalytic Hydrogen Generation System Using a Nickel-Thiolate Hexameric Cluster

Kagalwala

Gottlieb

et al. 2013

Inorg. Chem.

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We report the use of a nickel-thiolate hexameric cluster, Ni6(SC2H4Ph)12, for photocatalytic hydrogen production from water. The nickel cluster was synthesized ex-situ and characterized by various techniques. Single crystal X-ray analysis, (1)H NMR, 2D COSY, ESI-MS, UV-visible spectroscopy, and TGA provided insight into the structure and confirmed the purity and stability of the cluster. Cyclic voltammetry helped confirm hydrogen evolution reaction (HER) activity of this catalyst. Photoreactions carried out using an iridium photosensitizer, Ir(F-mppy)2(dtbbpy)[PF6], and TEA as the sacrificial reductant revealed the high activity of the Ni6 cluster as a water reducing catalyst. High TONs (3750) and TOFs (970 h(-1)) were obtained at optimum catalyst concentration (0.025 mM), with low concentrations of catalyst yielding up to 30,000 turnovers. Quenching studies, along with the evidence obtained from the electrochemical analysis, showed that this water reduction system proceeds through a reductive quenching mechanism. Mercury poisoning studies confirmed that no active, metallic colloids were formed during the photocatalytic reaction.

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Synthesis and Structure Analysis of α and β Forms of [12] Metallacrown-6 Nickel(II) Complex: [Ni₆(SCH₂CH₂CH₃)₁₂]

Cited by 7 publications

References 22 publications

Electrocatalytic Oxygen Evolution with an Atomically Precise Nickel Catalyst

Electrocatalytic Oxygen Evolution with an Atomically Precise Nickel Catalyst

Synthesis and Structures of Cuprous Triptycylthiolate Complexes

Photocatalytic Hydrogen Generation System Using a Nickel-Thiolate Hexameric Cluster

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