Penta and hexanuclear nickel tiara-like clusters with two different thiolate bridges

Tan, Chunhong; Jin, Muchun; Zhang, Hao; Hu, Shengmin; Sheng, Tianlu; Wu, Xintao

doi:10.1039/c5ce00863h

Cited by 11 publications

(13 citation statements)

References 53 publications

(136 reference statements)

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“…To support this assertion, we note that many similar Ni(II) thiolate clusters, including [Ni(SPh)2]x (x = 9, 11), [Ni(SCH2C(O)OEt)2]8, and [Ni(SCH2CH2 i Pr)2]6, have been previously reported, and these were synthesized using standard organometallic metathetical protocols. [36][37][38] Thus, while one-and two-phase Brust-Schiffrin protocols can be beneficial for nanoparticle syntheses, there is no reason to believe that Brust-Schiffrin is necessary for the synthesis of the Ni6 cluster. In the end, the utilization of Brust-Schiffrin protocol in this example likely only makes it more difficult to generate pure material.…”

Section: Case Study #2: Thiolate-protected Ni Nanoclustersmentioning

confidence: 99%

Case Studies in Nanocluster Synthesis and Characterization: Challenges and Opportunities

2018

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Atomically Precise Nanoclusters (APNCs) are an emerging area of nanoscience. Their mono-dispersity and well-defined arrangement of capping ligands facilitates the interrogation of their fundamental physical properties, allowing for the development of structurefunction relationships, as well as their optimization for a variety of applications, including quantum computing, solid-state memory, catalysis, sensing, and imaging. However, AP-NCs present several unique synthetic and characterization challenges. For example, nanocluster syntheses are infamously low yielding and often generate complicated mixtures. This combination of factors makes nanocluster purification and characterization more difficult than that of typical inorganic or organometallic complexes. Yet, while this fact is undoubtedly true, the past lessons learned from the characterization of inorganic complexes are still useful today. In this Account, we discuss six case studies taken from the recent literature in an attempt to identify common challenges and pitfalls encountered in APNC synthesis and characterization. For example, we show that several reducing agents employed in APNC synthesis, including the commonly used reagent NaBH4, do not always behave as anticipated. Indeed, we highlight one case where NaBH4 reduces the ligand and not the metal center, and other cases where NaBH4 acts as a Brønstead base instead of a reducing agent. In addition, we have identified several instances where the use of phase transfer agents, which were added to mediate APNC formation, played no role in the nanocluster synthesis, and likely made the isolation of pure material more difficult. We have also identified several cases of cluster misidentification driven by spurious or ambiguous characterization data, most commonly collected by mass spectrometry. To address these challenges, we propose that the nanocluster community adopt a standard protocol of characterization, similar to those used by the organometallic and coordination chemistry communities. This protocol requires that many complementary techniques be used in concert to confirm formulation, structure, and analytical purity of APNC samples. Two techniques that are under-utilized in this regard are combustion analysis and NMR spectroscopy. NMR spectroscopy, in particular, can provide information on purity and formulation that are difficult to collect with any other technique. X-ray absorption spectroscopy is another powerful method of nanocluster characterization, especially in cases where single crystals for X-ray diffraction are not forthcoming. Chromatographic techniques can also be extremely valuable for assessing purity, but are rarely used during APNC characterization. Our goal with this Account is to begin a discussion with respect to the best protocols for nanocluster synthesis and characterization. We believe that embracing a standard characterization protocol would make APNC synthesis more reliable, thereby accelerating their integration into a variety of technologies.

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Section: Case Study #2: Thiolate-protected Ni Nanoclustersmentioning

confidence: 99%

Case Studies in Nanocluster Synthesis and Characterization: Challenges and Opportunities

2018

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“…These reports include the discrete Ni(II) homoleptic thiolate complexes, [Ni 2 (SR) 4 ] 2– ; , mononuclear mixed ligand Ni(II) complexes of the type [Ni(SR) 2 PMe 2 Ph) 2 ] (L = PMe 2 Ph), [Ni(SR) 2 (Ph 2 PCH 2 CH 2 PPh 2 )], , [Ni(SR)L 1 L 2 ] 1+ , [Ni(SR) 2 L] (L 1 = t BuNC, L 2 = 1,2-bis(diisopropylphosphino)ethane), [Ni(SR)L] (L is a bidentate β-diketiminate (“nacnac”) ligand), and [Ni(SR)L] 1+ (L = (Ph 2 PCH 2 CH 2 ) 2 PPh); , thiolate bridged dimeric Ni(II) complexes; ,, and various thiolate bridged multinuclear Ni(II) complexes such as the recently reported trinuclear T-shaped Ni 3 S 8 complex, [Ni 3 (SCH 2 CH 2 CH 2 S) 4 ] 2– , which promotes the electrocatalytic reduction of N 2 to hydrazine. Several mononuclear nickel–thiolate complexes have been explored for the intramolecular proton transfer between nickel and coordinated thiolate, ,, while some nickel–pyridine thiolate complexes have been studied for ligand noninnocence and photocatalytic production of hydrogen. , On the other hand, a majority of research involving heterometallic nickel thiolate/sulfide compounds has been directed toward the model chemistry of nickel containing enzymes, such as [NiFe]-hydrogenases − and [NiFe]-carbon monoxide dehydrogenases/acetyl coenzyme A synthase. ,,− The synthesis of mononuclear nickel complexes in different ligand systems − and interactions of some of these complexes with CO 2 and CO in relation with the active site of the aforementioned enzymes have also been studied for a long time.…”

Section: Introductionmentioning

confidence: 99%

Thiolate Coordination vs C–S Bond Cleavage of Thiolates in Dinickel(II) Complexes

2021

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A detailed study for the synthesis of dinickel(II)–thiolate and dinickel(II)–hydrosulfide complexes and the complete characterization of the relevant intermediates involved in the C–S bond cleavage of thiolates are presented. Hydrated Ni(II) salts mediate the hydrolytic C–S bond cleavage of thiolates (NaSR/RSH; R = Me, Et, n Bu, t Bu), albeit inefficiently, to yield a mixture of a dinickel(II)–hydrosulfide complex, [Ni2(BPMP)(μ-SH)(DMF)2]2+ (1), and the corresponding dinickel(II)–thiolate complexes, such as [Ni2(BPMP)(μ-SEt)(ClO4)]1+ (2) (HBPMP is 2,6-bis[[bis(2-pyridylmethyl)amino]methyl]-4-methylphenol). A systematic study for the reactivity of thiolates with Ni(II) was therefore pursued which finally yielded 1 as a pure product which has been characterized in comparison with the dinickel(II)–dichloride complex, [Ni2(BPMP)(Cl)2(MeOH)2]1+ (3). While the reaction of thiolates with anhydrous Ni(OTf)2 in dry conditions could only yield [Ni2(BPMP)(OTf)2]1+ (5) instead of the expected dinickel(II)–thiolate compound, the C–S bond cleavage could be suppressed by the use of a chelating thiol, such as PhCOSH, to yield [Ni2(BPMP)(SCOPh)2]1+ (6). Finally, with the suitable choice of a monodentate thiol, a dinickel(II)–monothiolate complex, [Ni2(BPMP)(SPh)(DMF)(MeOH)(H2O)]2+ (7), was isolated as a pure product within 1 h of reaction, which after a longer time of reaction yielded 1 and PhOH. Complex 7 may thus be regarded as the intermediate that precedes the C–S bond cleavage and is generated by the reaction of a thiolate with an initially formed dinickel(II)–solvento complex, [Ni2(BPMP)(MeOH)2(H2O)2]3+(4). Selected dinickel(II) complexes were explored further for the scope of substitution reactions, and the results include the isolation of a dinickel(II)–bis(thiolate) complex, [Ni2(BPMP)(μ-SPh)2]1+ (8).

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“…15 Modification of the thiolate ligands adds further diversity to the complexes reported, particularly in the cases of multiligand complexes. 1,2,12,16 Thus, in this study, we report the influence of ligand functionality on the nuclearity of such complexes and demonstrate that through the incorporation of hydrogen-bonding capability, in the form of amide groups, it is possible to significantly influence the nuclearity of the resulting [Pd(SR) 2 ] n tiara complexes.…”

Section: Introductionmentioning

confidence: 62%

Influence of Hydrogen-Bonding Interactions on Nuclearity and Structure of Palladium Tiara-like Complexes

et al. 2018

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The role of intramolecular hydrogen-bonding interactions upon the nuclearity of palladium tiara-like complexes is reported herein. The synthesis of three palladium tiaras is described with three related thiolate ligands that vary in their hydrogen-bonding capability, amide vs ester for N -acetylcysteamine (tiara 1 ) vs 2-mercaptoethyl acetate (tiara 2 ) or ethyl thioglycolate (tiara 3 ), and in the relative position of the ester group, 2-mercaptoethyl acetate ( 2 ) or ethyl thioglycolate ( 3 ). Mass spectrometry indicates that, in the absence of protic solvents, N -acetylcysteamine reacts to form exclusively a six-membered tiara, [Pd(SCH 2 CH 2 NHCOCH 3 ) 2 ] 6 , 1 , whereas the ester containing analogues form both six- and eight-membered tiaras. Single-crystal X-ray diffraction studies indicate the significance of intramolecular N–H···O hydrogen bonds in determining the nuclearity of the amide-containing tiara 1 . NMR studies indicate that 1 is not in equilibrium with larger tiaras in solution, and that the smaller size of the aggregate inhibits the fluxional behavior of the pendant thiolate ligands, typically observed for larger tiaras. Electrochemical investigations of 1 reveal reductive processes that exhibit an increase in current upon addition of acid, along with the formation of palladium nanoparticles.

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Penta and hexanuclear nickel tiara-like clusters with two different thiolate bridges

Cited by 11 publications

References 53 publications

Case Studies in Nanocluster Synthesis and Characterization: Challenges and Opportunities

Case Studies in Nanocluster Synthesis and Characterization: Challenges and Opportunities

Thiolate Coordination vs C–S Bond Cleavage of Thiolates in Dinickel(II) Complexes

Influence of Hydrogen-Bonding Interactions on Nuclearity and Structure of Palladium Tiara-like Complexes

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