形式电荷与配体对无支撑双核铱(II)配合物性能影响的研究

铱配合物因其独特的电子分布，在催化剂制备、有机发光二极管技术和光动力治疗等领域展现出广泛的应用潜力。而由单一金属–金属键连接的无支撑双核铱( II)配合物，不仅提供额外的反应位点和多样化的赤道面及轴位配体类型，还能增强金属–金属至配体电荷转移（MMLCT），在光学性能方面备受瞩目。然而，这类配合物因为合成难度大和性质没有进行深入探索的问题，限制了其研究与应用的进一步发展。

因此，为深入研究无支撑双核铱( I I )配合物中金属–金属键和立体结构对其光物理性质及电化学性能的影响，本文设计并合成了一系列具有不同形式电荷的无支撑双核铱( I I )配合物。通过调节赤道面螯合配体咪唑环N 上的氢原子数量和轴位配体，成功合成了形式电荷范围从0 至+ 4 的双核铱( I I )金属配合物。配合物的晶体结构显示，其金属–金属键长对形式电荷的依赖性较小。然而，当轴位配体由三苯基膦（P P h 3）替换为碘离子（I －）后，金属–金属键长会受到配体的反位影响而缩短，这一结果揭示了配体类型对金属–金属键长的影响。在无支撑双核铱( I I )配合物光学性能的研究中，碘取代的配合物没有明显的光学特征，而轴位配体为P P h 3 时，配合物具有来自d σ ( I r – I r )→π * (N^N^N)的MMLCT 磷光发射特性，且可通过赤道面螯合配体的修饰进行调控。

同时，调控螯合配体中咪唑环N 原子上的氢原子数量会主要影响配体上的还原反应，配合物的形式电荷越低，展现出的还原电势越高。此外，轴位配体的更换不仅影响了配合物发生在金属中心的氧化过程，也对还原过程产生了影响。通过引入给电子基团和增大共轭结构，实现了对配合物光学性能和电化学性能的调控。

本文通过调控无支撑双核铱( I I )金属配合物的形式电荷与赤道面螯合配体的结构，深入研究了这类配合物的结构、光物理性质和稳定性等重要性质之间的互相影响与联系，为探索它们可能的应用领域提供了研究的基础。

[1] DUTTA I, SARBAJNA A, PANDEY P, et al. Acceptorless dehydrogenation of alcohols on a diruthenium(II,II) platform [J]. Organometallics, 2016, 35(10): 1505-1513.
[2] SAILER J K, SHARLAND J C, BACSA J, et al. Diruthenium tetracarboxylate-catalyzed enantioselective cyclopropanation with aryldiazoacetates [J]. Organometallics, 2023, 42(15): 2122-2133.
[3] LA MANNA S, DI NATALE C, PANZETTA V, et al. A diruthenium metallodrug as a potent inhibitor of amyloid-beta aggregation: Synergism of mechanisms of action [J]. Inorganic Chemistry, 2024, 63(1): 564-575.
[4] WERLE C, GODDARD R, PHILIPPS P, et al. Structures of reactive donor/acceptor and donor/donor rhodium carbenes in the solid state and their implications for catalysis [J]. Journal of the American Chemical Society, 2016, 138(11): 3797-3805.
[5] FORTUNATO M T, MOORE C E, TURRO C. Ligand-centered photocatalytic hydrogen production in an axially capped Rh2(II,II) paddlewheel complex with red light [J]. Journal of the American Chemical Society, 2023, 145(50): 27348-27357.
[6] POWERS D C, HWANG S J, ANDERSON B L, et al. Stereoelectronic effects in Cl2 elimination from binuclear Pt(III) complexes [J]. Inorganic Chemistry, 2016, 55(22): 11815-11820.
[7] MELENDO I, FUERTES S, MARTIN A, et al. NIR-II emission from cyclometalated dinuclear Pt(III) complexes [J]. Inorganic Chemistry, 2024, 63(12): 5470-5480.
[8] SINGH S, SHINDE V N, KUMAR S, et al. Mono and dinuclear palladium pincer complexes of nnse ligand as a catalyst for decarboxylative direct C-H heteroarylation of (Hetero)arenes [J]. Chemistry-An Asian Journal, 2023, 18(19): e202300628.
[9] KUO J L, GOLDBERG K I. Metal/ligand proton tautomerism facilitates dinuclear H2 reductive elimination [J]. Journal of the American Chemical Society, 2020, 142(51): 21439-21449.
[10] RUBIO-PEREZ L, IGLESIAS M, MUNARRIZ J, et al. A bimetallic iridium(ii) catalyst: [Ir(IDipp)(H)2][BF4]2 (IDipp = 1,3-bis(2,6-diisopropylphenylimidazol-2-ylidene)) [J]. Chemical Communications, 2015, 51(48): 9860-9863.
[11] CHEN T R, WU F S, LEE H P, et al. Diiridium bimetallic complexes function as a redox switch to directly split carbonate into carbon monoxide and oxygen [J]. Journal of the American Chemical Society, 2016, 138(11): 3643-3646.
[12] KIM J, SHIN K, JIN S, et al. Oxidatively induced reductive elimination: Exploring the scope and catalyst systems with Ir, Rh, and Ru complexes [J]. Journal of the American Chemical Society, 2019, 141(9): 4137-4146.
[13] VILA J, SOLA M, ACHARD T, et al. Rh(I) complexes with hemilabile thioether-functionalized nhc ligands as catalysts for
[2 + 2 + 2] cycloaddition of 1,5-bisallenes and alkynes [J]. ACS Catalysis, 2023, 13(5): 3201-3210.
[14] FORSON K G, OWENS R N, PARKMAN J A, et al. Allene trifluoroacetoxylation with a 2-phosphinoimidazole-derived bimetallic Rh(II) catalyst [J]. ACS Catalysis, 2023, 13(19): 12458-12463.
[15] CHEN H, YANG W, ZHANG J, et al. Divergent geminal alkynylation-allylation and acylation-allylation of carbenes: Evolution and roles of two transition-metal catalysts [J]. Journal of the American Chemical Society, 2024, 146(7): 4727-4740.
[16] SANTRA D C, MONDAL S, YOSHIDA T, et al. Ru(II)-based metallo-supramolecular polymer with tetrakis(N-methylbenzimidazolyl)bipyridine for a durable, nonvolatile, and electrochromic device driven at 0.6 V [J]. ACS Applied Materials Interfaces, 2021, 13(26): 31153-31162.
[17] YANG L, HENDSBEE A D, XUE Q, et al. Atomic precision graphene model compound for bright electrochemiluminescence and organic light-emitting diodes [J]. ACS Applied Materials Interfaces, 2020, 12(46): 51736-51743.
[18] BENDARY S H, BETIHA M A, HUSSEIN M F, et al. Solar energy conversion to electricity by tris (2,2′-bipyirdyl) ruthenium(II) chloride hexahydrate-diethyl ammonium tetrachloroferrate-oxalic acid photogalvanic cell: Statistical analysis [J]. Journal of Molecular Liquids, 2022, 347.
[19] GROSS P, IM H, LAWS D, et al. Enantioselective aziridination of unactivated terminal alkenes using a planar chiral Rh(III) indenyl catalyst [J]. Journal of the American Chemical Society, 2024, 146(2): 1447-1454.
[20] QIU Z, DENG H, NEUMANN C N. Site-isolated Rhodium(II) metalloradicals catalyze olefin hydrofunctionalization [J]. Angewandte Chemie International Edition, 2024: e202401375.
[21] LI C C, XU R, LIU X Y, et al. Visible self-luminous indium-based metal–organic framework for electrochemiluminescence detection of Hg2+ [J]. Sensors and Actuators B: Chemical, 2024, 405.
[22] PRIETO OTOYA T D, MCQUAID K T, HENNESSY J, et al. Probing a major DNA weakness: Resolving the groove and sequence selectivity of the diimine complex lambda-[Ru(phen)2phi]2+ [J]. Angewandte Chemie International Edition, 2024, 63(13): e202318863.
[23] WEI J, TANG H, SHENG L, et al. Site-specific metal-support interaction to switch the activity of Ir single atoms for oxygen evolution reaction [J]. Nature Communications, 2024, 15(1): 559.
[24] HUA K, LI X, RUI Z, et al. Integrating atomically dispersed ir sites in MnCo2O4.5 for highly stable acidic oxygen evolution reaction [J]. ACS Catalysis, 2024, 14(5): 3712-3724.
[25] QI Y, ZHANG B Y, ZHANG G H, et al. Efficient overall water splitting of a suspended photocatalyst boosted by metal-support interaction [J]. Joule, 2024, 8(1): 193-203.
[26] ZHENG Z, WANG L, XIN Y Y, et al. Iridium(III) carbene phosphors with fast radiative transitions for blue organic light emitting diodes and hyperphosphorescence [J]. Advanced Functional Materials, 2024.
[27] YAN Z P, WANG Z H, ZHUANG X M, et al. A steric interlocked phosphorescent iridium(III) complex toward ultrapure green electroluminescence [J]. Advanced Optical Materials, 2024.
[28] LI Y, LUO S, WANG H, et al. Photoacidolysis-mediated iridium(III) complex for photoactive antibacterial therapy [J]. Journal of Medicinal Chemistry, 2023, 66(7): 4840-4848.
[29] WANG Y, LUO Y Z, LIU Z J, et al. Cationic n,s-chelate half-sandwich iridium complexes: Synthesis, characterization, anticancer and antiplasmodial activity [J]. Biomaterials Science, 2023, 11(21): 7090-7098.
[30] ZONG C C, ZHENG W, YANG Y, et al. Ru/Ir nanojunctions supported on CNTs as active and ultrastable catalysts for CO preferential oxidation toward hydrogen purification [J]. Chemical Engineering Journal, 2024, 481.
[31] HUANG J J, ZHONG C L, XIA Y J, et al. Multifunctional catalytic sites regulation of atomic-scale iridium on orthorhombic-CoSe2 for high efficiency dual-functional alkaline hydrogen evolution and organic degradation [J]. Journal of Energy Chemistry, 2024, 92: 271-281.
[32] TAIE Z, PENG X, KULKARNI D, et al. Pathway to complete energy sector decarbonization with available iridium resources using ultralow loaded water electrolyzers [J]. ACS Applied Material Interfaces, 2020, 12(47): 52701-52712.
[33] ZHELAVSKYI O, PARIKH S, JHANG Y J, et al. Green light promoted iridium(III)/copper(I)-catalyzed addition of alkynes to aziridinoquinoxalines through the intermediacy of azomethine ylides [J]. Angewandte Chemie International Edition, 2024: e202318876.
[34] WANG W F, LU K, LIU P R, et al. Regioselective 1,n-diborylation of alkylidenecyclopropanes enabled by catalysis with a spirocyclic nhc irIII pincer complex [J]. ACS Catalysis, 2024: 5156-5166.
[35] YANG X, XU S, ZHANG Y, et al. Narrowband pure near-infrared (NIR) Ir(III) complexes for solution-processed organic light-emitting diode (OLED) with external quantum efficiency over 16% [J]. Angewandte Chemie International Edition, 2023, 62(41): e202309739.
[36] YAN J, QU Z H, ZHOU D Y, et al. Bis-tridentate Ir(III) phosphors and blue hyperphosphorescence with suppressed efficiency roll-off at high brightness [J]. ACS Applied Materials Interfaces, 2024, 16(3): 3809-3818.
[37] YAN Z P, MAO M X, LIU Q M, et al. Rigidity‐enhanced narrowband iridium(iii) complexes with finely‐optimized emission spectra for efficient pure‐red electroluminescence [J]. Advanced Functional Materials, 2024.
[38] CHEN W, QIU M, TU R, et al. Aggregation-induced near-infrared emission and electrochemiluminescence of an iridium(III) complex for ampicillin sodium sensing [J]. Inorganic Chemistry, 2023, 62(29): 11708-11717.
[39] KRITCHENKOV I S, SOLOMATINA A I, KOZINA D O, et al. Biocompatible Ir(III) complexes as oxygen sensors for phosphorescence lifetime imaging [J]. Molecules, 2021, 26(10).
[40] HUANG H, BANERJEE S, QIU K, et al. Targeted photoredox catalysis in cancer cells [J]. Nature Chemistry, 2019, 11(11): 1041-1048.
[41] GONZALO-NAVARRO C, ZAFON E, ORGANERO J A, et al. Ir(III) half-sandwich photosensitizers with a π-expansive ligand for efficient anticancer photodynamic therapy [J]. Journal of Medicinal Chemistry, 2024, 67(3): 1783-1811.
[42] LIU C, ZHOU L, WEI F, et al. Versatile strategy to generate a rhodamine triplet state as mitochondria-targeting visible-light photosensitizers for efficient photodynamic therapy [J]. ACS Applied Materials Interfaces, 2019, 11(9): 8797-8806.
[43] KAUR M, ADHIKARI M, MANAR K K, et al. BICAAC-derived covalent and cationic Ir(I) complexes: Application of Ir(BICAAC)Cl(COD) complexes as catalysts for transfer hydrogenation and hydrosilylation reactions [J]. Inorganic Chemistry, 2024, 63(3): 1513-1523.
[44] GUPTA P, DREXLER H J, WINGAD R, et al. P,N-type phosphaalkene-based Ir(I) complexes: synthesis, coordination chemistry, and catalytic applications [J]. Inorganic Chemistry Frontiers, 2023, 10(8): 2285-2293.
[45] JAEGERS N R, KHIVANTSEV K, KOVARIK L, et al. Catalytic activation of ethylene C–H bonds on uniform d8 Ir(I) and Ni(II) cations in zeolites: Toward molecular level understanding of ethylene polymerization on heterogeneous catalysts [J]. Catalysis Science & Technology, 2019, 9(23): 6570-6576.
[46] MAK K H G, CHAN P K, FAN W Y, et al. Photochemical reaction of Cp*Ir(Co)2 with C6F5X (X = Cn, F): Formation of diiridium(II) complexes [J]. Organometallics, 2013, 32(4): 1053-1059.
[47] PALERMO A P, ZHANG S, OKRUT A, et al. Remotely bonded bridging dioxygen ligands enhance hydrogen transfer in a silica-supported tetrairidium cluster catalyst [J]. Journal of the American Chemical Society, 2024, 146(6): 3773-3784.
[48] LEE H P, HSU Y F, CHEN T R, et al. A novel cyclometalated dimeric iridium complex, [(dfpbo)2Ir]2 [dfpbo = 2-(3,5-difluorophenyl)benzoxazolato-N,C2'], containing an unsupported Ir(II)-Ir(II) bond [J]. Inorganic Chemistry, 2009, 48(4): 1263-1265.
[49] COTTON F A, CURTIS N F, HARRIS C B, et al. Mononuclear and polynuclear chemistry of rhenium (III): Its pronounced homophilicity [J]. SCIENCE, 1964, 145(3638): 1305-1307.
[50] GOULD C A, MCCLAIN K R, RETA D, et al. Ultrahard magnetism from mixed-valence dilanthanide complexes with metal-metal bonding [J]. SCIENCE, 2022, 375(6577): 198-202.
[51] SCHIAVO S L, PIRAINO P, BONAVITA A, et al. A dirhodium(II,II) molecular species as a candidate material for resistive carbon monoxide gas sensors [J]. Sensors and Actuators B: Chemical, 2008, 129(2): 772-778.
[52] YI X, LIU B, CHEN K, et al. Unbridged Rh(II)-Rh(II) complexes of N-heterocyclic carbenes and reactions with O2 to form dirhodium(μ-η1:η1-O2) complexes [J]. Dalton Transactions, 2019, 48(12): 3835-3839.
[53] RASMUSSEN P G, ANDERSON J E, BAILEY O H, et al. A novel metal-metal bonded iridium(II) dimer [J]. Journal of the American Chemical Society, 2002, 107(1): 279-281.
[54] HüCKSTäDT H, HOMBORG H. Dimere IrII‐Phthalocyaninate mit (Ir-Ir)‐Bindung; Kristallstruktur von Di(pyridinphthalocyaninato(2-)‐iridium(II)) [J]. Zeitschrift für anorganische und allgemeine Chemie, 2004, 623(1-6): 369-378.
[55] HEINEKEY D M, FINE D A, BARNHART D. Protonation of metal−metal bonds in dinuclear iridium complexes:  Consequences for structure and reactivity [J]. Organometallics, 1997, 16(12): 2530-2538.
[56] FENG M Q, CHAN K S. Synthesis and reactivity of nonbridged metal-metal bonded rhodium and iridium phenanthroline-based NO dimers [J]. Organometallics, 2002, 21(13): 2743-2750.
[57] PATRA S K, RAHAMAN S M, MAJUMDAR M, et al. A rare unsupported iridium(II) dimer, [IrCl2(CO)2]2 [J]. Chemical Communications, 2008, (22): 2511-2513.
[58] HUANG H, RHEINGOLD A L, HUGHES R P. Serendipitous Discovery of a Simple Compound with an Unsupported Ir−Ir Bond [J]. Organometallics, 2009, 28(5): 1575-1578.
[59] ZHENG F, YANG Y, WU S, et al. Structure-property relationships of photofunctional diiridium(II) complexes with tetracationic charge and an unsupported Ir-ir bond [J]. Communications Chemistry, 2022, 5(1): 159.
[60] KOSE M. Synthesis, characterization, and antimicrobial properties of two Cu(II) complexes derived from a benzimidazole ligand [J]. Journal of Coordination Chemistry, 2014, 67(14): 2377-2392.