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Quiroz M, Darensbourg MY. Development of (NO)Fe(N 2S 2) as a Metallodithiolate Spin Probe Ligand: A Case Study Approach. Acc Chem Res 2024; 57:831-844. [PMID: 38416694 PMCID: PMC10979402 DOI: 10.1021/acs.accounts.3c00667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 02/14/2024] [Accepted: 02/15/2024] [Indexed: 03/01/2024]
Abstract
ConspectusThe ubiquity of sulfur-metal connections in nature inspires the design of bi- and multimetallic systems in synthetic inorganic chemistry. Common motifs for biocatalysts developed in evolutionary biology include the placement of metals in close proximity with flexible sulfur bridges as well as the presence of π-acidic/delocalizing ligands. This Account will delve into the development of a (NO)Fe(N2S2) metallodithiolate ligand that harnesses these principles. The Fe(NO) unit is the centroid of a N2S2 donor field, which as a whole is capable of serving as a redox-active, bidentate S-donor ligand. Its paramagnetism as well as the ν(NO) vibrational monitor can be exploited in the development of new classes of heterobimetallic complexes. We offer four examples in which the unpaired electron on the {Fe(NO)}7 unit is spin-paired with adjacent paramagnets in proximal and distal positions.First, the exceptional stability of the (NO)Fe(N2S2)-Fe(NO)2 platform, which permits its isolation and structural characterization at three distinct redox levels, is linked to the charge delocalization occurring on both the Fe(NO) and the Fe(NO)2 supports. This accommodates the formation of a rare nonheme {Fe(NO)}8 triplet state, with a linear configuration. A subsequent FeNi complex, featuring redox-active ligands on both metals (NO on iron and dithiolene on nickel), displayed unexpected physical properties. Our research showed good reversibility in two redox processes, allowing isolation in reduced and oxidized forms. Various spectroscopic and crystallographic analyses confirmed these states, and Mössbauer data supported the redox change at the iron site upon reduction. Oxidation of the complex produced a dimeric dication, revealing an intriguing magnetic behavior. The monomer appears as a spin-coupled diradical between {Fe(NO)}7 and the nickel dithiolene monoradical, while dimerization couples the latter radical units via a Ni2S2 rhomb. Magnetic data (SQUID) on the dimer dication found a singlet ground state with a thermally accessible triplet state that is responsible for magnetism. A theoretical model built on an H4 chain explains this unexpected ferromagnetic low-energy triplet state arising from the antiferromagnetic coupling of a four-radical molecular conglomerate. For comparison, two (NO)Fe(N2S2) were connected through diamagnetic group 10 cations producing diradical trimetallic complexes. Antiferromagnetic coupling is observed between {Fe(NO)}7 units, with exchange coupling constants (J) of -3, -23, and -124 cm-1 for NiII, PdII, and PtII, respectively. This trend is explained by the enhanced covalency and polarizability of sulfur-dense metallodithiolate ligands. A central paramagnetic trans-Cr(NO)(MeCN) receiver unit core results in a cissoid structural topology, influenced by the stereoactivity of the lone pair(s) on the sulfur donors. This {Cr(NO)}5 radical bridge, unlike all previous cases, finds the coupling between the distal Fe(NO) radicals to be ferromagnetic (J = 24 cm-1).The stability and predictability of this S = 1/2 moiety and the steric/electronic properties of the bridging thiolate sulfurs suggest it to be a likely candidate for the development of novel molecular (magnetic) compounds and possibly materials. The role of synthetic inorganic chemistry in designing synthons that permit connections of the (NO)Fe(N2S2) metalloligand is highlighted as well as the properties of the heterobi- and polymetallic complexes derived therefrom.
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Affiliation(s)
- Manuel Quiroz
- Department of Chemistry, Texas
A & M University, College Station, Texas 77843, United States
| | - Marcetta Y. Darensbourg
- Department of Chemistry, Texas
A & M University, College Station, Texas 77843, United States
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Wu C, Kakarla LN, Chandrasekaran CP, Zhang X, Mague JT, Sproules S, Donahue JP. Asymmetric by Design: Heteroleptic Coordination Compounds with Redox-Active Dithiolene and 1,2,4,5-Tetrakis(isopropylthio)benzene Ligands. Inorg Chem 2024; 63:173-183. [PMID: 38134365 PMCID: PMC10777400 DOI: 10.1021/acs.inorgchem.3c02928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 11/22/2023] [Accepted: 11/24/2023] [Indexed: 12/24/2023]
Abstract
The 1,2,4,5-tetrakis(alkylthio)benzenes are redox-active organosulfur molecules that support oxidation to a stable radical cation. Their utility as ligands for the assembly of multimetal complexes with tailored functionality/property is unexamined. Here, 1,2,4,5-tetrakis(isopropylthio)benzene (tptbz, 1) is shown to bind PdCl2 at either one end, leaving the other open, or at both ends to form centrosymmetric [Cl2Pd(tptbz)PdCl2], 4. Ligand metathesis between Na2[(N≡C)2C2S2] (Na2mnt) and [Cl2M(tptbz)] (M = Pd, 2; M = Pt, 3) yields [(mnt)M(tptbz)] (M = Pd, 5; M = Pt, 6), but an alternative route involving transmetalation with [(mnt)SnMe2] delivers substantially greater yield. The mixed dithiolene-dithioether compound [(Ph2C2S2)Pt(tptbz)] (8) is formed by a similar transmetalation protocol using [(Ph2C2S2)SnnBu2]. Compounds 5, 6, and 8 are the first such heteroleptic complexes prepared by deliberate synthesis. The cyclic voltammetry of 8 reveals anodic waves at +0.14 and +0.97 V vs Fc+/Fc, which are attributed to successive dithiolene oxidation processes. While oxidized at +0.73 V as a free ligand, the redox-active MO of tptbz is pushed to a higher potential upon coordination to Pt2+ and is inaccessible. Calculations of the structures of [8]+ and of [((Cl2-3,5-C6H3)2C2S2)Pt(tptbz)]+ show that, in the latter, the dithiolene MOs are drawn down in energy into proximity with the tptbz MOs.
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Affiliation(s)
- Che Wu
- Department
of Chemistry, Tulane University, 6400 Freret Street, New Orleans, Louisiana 70118-5698, United States
| | - Lakshmi Nishanth Kakarla
- Department
of Chemistry and Biochemistry, Lamar University, Beaumont, Texas 77710, United States
| | | | - Xiaodong Zhang
- Department
of Chemistry, Tulane University, 6400 Freret Street, New Orleans, Louisiana 70118-5698, United States
| | - Joel T. Mague
- Department
of Chemistry, Tulane University, 6400 Freret Street, New Orleans, Louisiana 70118-5698, United States
| | - Stephen Sproules
- WestCHEM,
School of Chemistry, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - James P. Donahue
- Department
of Chemistry, Tulane University, 6400 Freret Street, New Orleans, Louisiana 70118-5698, United States
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Verpekin VV, Chudin OS, Kondrasenko AA, Burmakina GV, Vasiliev AD, Zimonin DV, Rubaylo AI. Chemistry of vinylidene complexes—XXVII—new µ-vinylidene MnPt complexes with platinum-coordinated 1-adamantyl isocyanide ligand: spectroscopic, structural and electrochemical study. TRANSIT METAL CHEM 2022. [DOI: 10.1007/s11243-022-00511-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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4
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Quiroz M, Lockart MM, Saber MR, Vali SW, Elrod LC, Pierce BS, Hall MB, Darensbourg MY. Cooperative redox and spin activity from three redox congeners of sulfur-bridged iron nitrosyl and nickel dithiolene complexes. Proc Natl Acad Sci U S A 2022; 119:e2201240119. [PMID: 35696567 PMCID: PMC9233302 DOI: 10.1073/pnas.2201240119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Accepted: 05/06/2022] [Indexed: 12/15/2022] Open
Abstract
The synthesis of sulfur-bridged Fe-Ni heterobimetallics was inspired by Nature's strategies to "trick" abundant first row transition metals into enabling 2-electron processes: redox-active ligands (including pendant iron-sulfur clusters) and proximal metals. Our design to have redox-active ligands on each metal, NO on iron and dithiolene on nickel, resulted in the observation of unexpectedly intricate physical properties. The metallodithiolate, (NO)Fe(N2S2), reacts with a labile ligand derivative of [NiII(S2C2Ph2)]0, NiDT, yielding the expected S-bridged neutral adduct, FeNi, containing a doublet {Fe(NO)}7. Good reversibility of two redox events of FeNi led to isolation of reduced and oxidized congeners. Characterization by various spectroscopies and single-crystal X-ray diffraction concluded that reduction of the FeNi parent yielded [FeNi]-, a rare example of a high-spin {Fe(NO)}8, described as linear FeII(NO-). Mössbauer data is diagnostic for the redox change at the {Fe(NO)}7/8 site. Oxidation of FeNi generated the 2[FeNi]+⇌[Fe2Ni2]2+ equilibrium in solution; crystallization yields only the [Fe2Ni2]2+ dimer, isolated as PF6- and BArF- salts. The monomer is a spin-coupled diradical between {Fe(NO)}7 and NiDT+, while dimerization couples the two NiDT+ via a Ni2S2 rhomb. Magnetic susceptibility studies on the dimer found a singlet ground state with a thermally accessible triplet excited state responsible for the magnetism at 300 K (χMT = 0.67 emu·K·mol-1, µeff = 2.31 µB), and detectable by parallel-mode EPR spectroscopy at 20 to 50 K. A theoretical model built on an H4 chain explains this unexpected low energy triplet state arising from a combination of anti- and ferromagnetic coupling of a four-radical molecular conglomerate.
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Affiliation(s)
- Manuel Quiroz
- Department of Chemistry, Texas A&M University, College Station, TX 77843
| | - Molly M. Lockart
- Department of Chemistry & Biochemistry, Samford University, Birmingham, AL 35229
| | - Mohamed R. Saber
- Chemistry Department, Faculty of Science, Fayoum University, Fayoum 63514, Egypt
| | - Shaik Waseem Vali
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77845
| | - Lindy C. Elrod
- Department of Chemistry, Texas A&M University, College Station, TX 77843
| | - Brad S. Pierce
- Department of Chemistry & Biochemistry, University of Alabama, Tuscaloosa, AL 35487
| | - Michael B. Hall
- Department of Chemistry, Texas A&M University, College Station, TX 77843
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Pal N, Naskar T, Majumdar A. Synthesis, structural diversity and redox reactions in 1, 2- Bis(diphenylphopshinoethane)Nickel(II)-Thiolate complexes. Inorganica Chim Acta 2022. [DOI: 10.1016/j.ica.2021.120738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Das A, Ganguly T, Majumdar A. Thiolate Coordination vs C-S Bond Cleavage of Thiolates in Dinickel(II) Complexes. Inorg Chem 2021; 60:944-958. [PMID: 33405907 DOI: 10.1021/acs.inorgchem.0c03068] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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, nBu, tBu), 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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Affiliation(s)
- Ayan Das
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Kolkata 700032, India
| | - Tuhin Ganguly
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Kolkata 700032, India
| | - Amit Majumdar
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Kolkata 700032, India
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Selvakumar J, Simpson SM, Zurek E, Arumugam K. An electrochemically controlled release of NHCs using iron bis(dithiolene) N-heterocyclic carbene complexes. Inorg Chem Front 2021. [DOI: 10.1039/d0qi00638f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A series of five coordinated [Fe(NHC)(S2C2R2)2] complexes were isolated and subjected to electrochemical reduction for the facile release of NHCs in the catalytic media.
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Affiliation(s)
| | - Scott M. Simpson
- Department of Chemistry
- St. Bonaventure University
- St. Bonaventure
- USA
| | - Eva Zurek
- Department of Chemistry
- State University of New York at Buffalo
- Buffalo
- USA
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