Homodinuclear Complexes Research Articles

Chiral Homodinuclear Dysprosium Macrocyclic Complexes with Single‐Molecule Magnetic Behaviours

AbstractA pair of enantiomerically chiral dysprosium homodinuclear complexes: [(acac)4Dy2(R,R,R,R‐L)] (R‐Dy) and [(acac)4Dy2(S,S,S,S‐L)] (S‐Dy) (Hacac=acetylacetone) have been synthesized based on macrocyclic chiral ligands (R,R,R,R‐H2L or S,S,S,S‐H2L), derived from the [2+2] template condensation of 4‐tert‐butyl‐2,6‐diformylphenol, dysprosium acetylacetonate and (1R,2R)‐/(1S,2S)‐1,2‐cyclohexanediamine, respectively. Circular dichroism spectra confirms their enantiomeric chirality. Single‐crystal structures show two crystallographic independent dysprosium(III) ions have square antiprismatic coordination with different D4d local symmetry. Furthermore, the selected R‐Dy complex owns the slow magnetic relaxation behaviour with the ferromagnetic Dy3+⋅⋅⋅Dy3+ coupling.

Design and photophysical characterization of dinuclear lanthanide complexes incorporating spacer ligands along with their mononuclear analogues: A comparative study

Two heteroleptic homo-dinuclear complexes of Dy(III) and Sm(III) with pyrazine (pyz) as spacer ligand [Ln(TFPB)3(μ-pyz)Ln(TFPB)3], along with their mononuclear analogue [Ln(TFPB)3(pyz)2] were synthesized and characterized. Diketone TFPB (4,4,4-trifluoro-1-phenyl-1,3-butanedione) was incorporated as main ligand. NMR analysis depicted single peak for pyz protons for dinuclear complexes and two for mononuclear ones, which confirmed the bridging nature of pyz in former complexes. UV spectra revealed two absorption bands despite of the different metal ion and nuclearity of complex, suggesting the absorption of UV-radiation by coordinated moieties inspite of the metal ion involved. The emission spectra exhibited significant intensity of yellow and orange-red peaks for Dy(III) and Sm(III) complexes, respectively, indicating effective sensitization of metal center. The enhanced emission intensity observed in dinuclear Sm-complexes, compared to their mononuclear counterparts, indicates a synergistic effect of the two metal ions on the overall emission properties, rather than a mere additive effect that would be expected from two independent mononuclear units. The photoluminescent properties of synthesized complexes were examined and discussed, suggesting potential applications in display devices. The Correlated Color Temperature (CCT) of these complexes falls within a range suitable for warm light sources and the highest branching ratio observed for 4G5/2 → 6H9/2 (for Sm3+ ion) and 4F9/2 → 6H13/2 (for Dy3+ ion) transitions suggests potential application in laser amplification. The alignment between band gap measurements obtained from UV and CV analyses highlight the possibility of employing these complexes in semiconductor technologies.

Bright LanthanideIII Triboluminescence despite Low Photoluminescence, and Dual Triboluminescence and Mechano‐Responsive Photoluminescence

AbstractIn pursuit of a new family of mechanically responsive luminescent materials, it is aimed to differentiate triboluminescence (TL) from photoluminescence (PL). A β‐diketonate ligand with tert‐butyl groups (2,2,6,6‐tetramethylheptane‐3,5‐dionate: tmh) is selected to quench EuIII‐centered PL via ligand‐to‐metal charge transfer, whereas tmh provides efficient photosensitization of TbIII ions. Bright TL is observed from the EuIII and TbIII homodinuclear complexes despite the fact that their PL quantum yields differed by a factor of >50. Nanomechanical tests reveal the ductility of the crystals, suggesting they are ideal for accumulating deformation energy before breakage. Furthermore, a TL/PL color difference is observed for a TbIII/EuIII heterodinuclear complex, and grinding results in mechanochromic luminescence (MCL); this is the first example of a dual TL‐ and MCL‐active lanthanideIII coordination compound. The photophysical properties before, during, and after grinding are investigated and correlated with powder and single‐crystal crystallographic data.

New Ni(II)-Ni(II) Dinuclear Complex, a Resting State of the (α-diimine)NiBr2/AlMe3 Catalyst System for Ethylene Polymerization

A novel room-temperature stable diamagnetic nickel complex 2 was detected upon activation of Brookhart-type ethylene polymerization pre-catalyst LNiBr2 (1, L = 1,4-bis-2,4,6-trimethylphenyl-2,3-dimethyl-1,4-diazabuta-1,3-diene) with AlMe3. Using in situ 1H, 2H, and 13C NMR spectroscopy, as well as DFT calculations, this species has been identified as an antiferromagnetically coupled homodinuclear complex [LNiII(μ-Me)(μ-CH2)NiIIL]+Br−. Its behavior in the reaction solution is characteristic of the resting state of nickel catalyzed ethylene polymerization.

Synthesis and Characterization of Lanthanide Metal Ion Complexes of New Polydentate Hydrazone Schiff Base Ligand

The new homodinuclear complexes of the general formula [Ln2L3(NO3)3] (where HL is newly synthesized 2-((2-(benzoxazol-2-yl)-2-methylhydrazono)methyl)phenol and Ln = Sm3+ (1), Eu3+ (2), Tb3+ (3a, 3b), Dy3+ (4), Ho3+ (5), Er3+ (6), Tm3+ (7), Yb3+ (8)), have been synthesized from the lanthanide(III) nitrates with the polydentate hydrazone Schiff base ligand. The flexibility of this unsymmetrical Schiff base ligand containing N2O binding moiety, attractive for lanthanide metal ions, allowed for a self-assembly of these complexes. The compounds were characterized by spectroscopic data (ESI-MS, IR, UV/Vis, luminescence) and by the X-ray structure determination of the single crystals, all of which appeared to be different solvents. The analytical data suggested 2:3 metal:ligand stoichiometry in these complexes, and this was further confirmed by the structural results. The metal cations are nine-coordinated, by nitrogen and oxygen donor atoms. The complexes are two-centered, with three oxygen atoms in bridging positions. There are two types of structures, differing by the sources of terminal (non-bridging) coordination centers (group A: two ligands, one nitro anion/one ligand, two nitro anions, group B: three ligands, three anions).

Homodinuclear RhI and IrI Complexes Derived from Imidazolium‐Benzimidazolates

AbstractThe reactions of [M(μ‐Cl)(COD)]2 (M=Rh, Ir) with the conjugated mesomeric betaines 2‐(3‐methyl‐1‐imidazolium)‐benzimidazolate (1aH), 2‐(3‐isopropyl‐1‐imidazolium)‐benzimidazolate (1bH) and 2‐(3‐tert‐butyl‐1‐imidazolium)‐benzimidazolate (1cH) in equilibrium with their carbenic tautomers 1’aH, 1’bH and 1’cH were investigated. In the case of 1aH and 1bH, the homodinuclear complexes [MCl(COD){M(μ‐1’a)(COD)}] and [MCl(COD){M(μ‐1’b)(COD)}] were obtained, whose anionic NHC ligand 1’a− or 1’b− bridges the metal centres in a κ1N : κ1N mode, while binding the M(COD) moiety in a C,N‐chelating mode. For M=Ir, [IrCl(COD){Ir(μ‐1’’b)(COD)}] containing the “abnormal” NHC isomer 1’’b− was observed as a side product. In the case of 1’cH, [{RhCl(COD)}2(μ‐1cH)] containing a κ1N : κ1N benzimidazolato ligand was obtained for M=Rh, while for M=Ir the reaction furnished [IrCl(COD){Ir(μ‐1’’c)(COD)}], which contains the anionic “abnormal” NHC ligand 1’’c−. This difference in behaviour is rationalised by the propensity of iridium(I) for oxidative addition, which in the present case involves a C−H bond of the dangling formamidium unit of [{IrCl(COD)}2(μ‐1cH)] to afford [IrICl(COD){IrIIIHCl(μ‐1’’c)(COD)}], followed by reductive elimination of HCl. The crystal structures of the new complexes were determined by single‐crystal X‐ray diffraction, except for [IrCl(COD){Ir(μ‐1’a)(COD)}], where by serendipity the closely related mononuclear complex [Ir(1’a)(COD)] was structurally characterised instead.

Dinuclear metal complexes of a new hybrid phosphine-phosphonodithioate ligand

Reaction of Ph2PCH2OH and {RP(S)(μ-S)}2 (R = p-C6H4OMe, Lawesson's reagent), in toluene, gave the new hybrid PIII/PV ligand Ph2PCH2OP(S)(R)SH 1 in high yield. Unfortunately, attempts to crystallise 1 gave, instead, suitable X-ray quality crystals of the Zwitterion Ph2P+(CH2OH)CH2OP(S)(R)S−1′, presumably arising from the presence of some residual formaldehyde. Three homodinuclear complexes [Ru2(η6-p-CH3C6H4iPr)2{μ-Ph2PCH2OP(S)(R)S}Cl3] (2) and [M2(η5-C5(CH3)5)2{μ-Ph2PCH2OP(S)(R)S}Cl3] [M = Rh, 3; M = Ir, 4 (R = p-C6H4OCH3)] were obtained upon reaction of a 1:1 molar ratio of 1 and either [(η6-p-CH3C6H4iPr)RuCl(μ-Cl)]2 or [M(μ-Cl)(Cl)(η5-C5(CH3)5)2]2 (M = Rh and Ir), respectively. The mononuclear IrIII complex Ir(η5-C5(CH3)5)(Ph2PCH2OH)Cl25 was prepared for comparative spectroscopic and crystallographic purposes with 4. All compounds were characterised by a combination of multinuclear NMR and FT−IR spectroscopy and elemental analysis. In addition, the first example of a phosphine-dithiophosphonate ligand 1′ along with two homodinuclear complexes 2·CHCl3 and 4 were determined by single crystal X-ray diffraction. Compound 5 displays an intramolecular O(1)−H(1)···Cl(2) hydrogen bond to a terminal IrIII bound chloride ligand.

Interdependent Metal-Metal Bonding and Ligand Redox-Activity in a Series of Dinuclear Macrocyclic Complexes of Iron, Cobalt, and Nickel.

This report describes an isostructural series of dinuclear iron, cobalt, and nickel complexes bound by a redox-active macrocyclic ligand. The series spans five redox levels (34-38 e-/cluster core), allowing for a detailed investigation into both the degree of metal-metal interaction and the extent of ligand-based redox-activity. Magnetometry, electrochemistry, UV-vis-NIR absorption spectroscopy, and crystallography were used in conjunction with DFT computational analyses to extract the electronic structures of the six homodinuclear complexes. The isoelectronic, 34 e- species [(3PDI2)Fe2(PMe3)2(μ-Cl)](OTf) and [(3PDI2)Co2(PMe3)2(μ-Cl)](OTf)3 exhibit metal-metal single bonds, with varying amounts of electron density delocalization into the ligand as a function of the effective nuclear charge of the metal ions. One- and two-electron reductions of [(3PDI2)Co2(PMe3)2(μ-Cl)](OTf)3 lead to isolable products, which show successive increases in both the Co-Co distances and the extent of reduction of the ligand manifold. This trend results from reduction of a Co-Co σ* orbital, which was found to be heavily mixed with the redox-active manifold of the 3PDI2 ligand. A similar trend was observed in the 37 and 38 e- dinickel complexes [(3PDI2)Ni2(PMe3)2(μ-Cl)](OTf)2 and [(3PDI2)Ni2(PMe3)2(μ-Cl)](OTf); however, their higher electron counts lead to high-spin ground states that result from occupation of a high-lying δ/δ* manifold with significant Ni-NPDI σ* character. This change in ground state configuration reforms a M-M bonding interaction in the 37 e- complex, but formation of the 38 e- species again disrupts the M-M bond alongside the transfer of electron density to the ligand.

Impact of cyanide co-ligand to convert crystal structure of pyrazole-based copper coordination compounds from a dinuclear to a polymeric structure and DFT calculations of [Cu2(tpmp)X2] (X = Cl and I)

Two coordination copper (I) compounds containing pyrazole-based ligand of N, N, N′, N′-tetra-[3,5-dimethyl-1-pyrazolyl) methyl] –paraphenylenediamine (tpmp) namely [Cu2(tpmp)Cl2] (1) and [Cu3(tpmp)Cl CN2]n (2) were designed and synthesized. Reaction of tpmp ligand with Cu(I) in 1:2 ratio gives a discrete homodinuclear complex of 1, while addition of cyanide co-ligand leads to the formation of polymer 2. The considered compounds have been characterized by single-crystal X-ray diffraction, infrared spectroscopy and elemental analysis (CHN). The Cu(I) center in 1 is three-coordinated with a distorted trigonal geometry while in 2, cyanide functions as a bridging co-ligand to form a polymer with three types of coordination geometries around the copper atoms including, distorted linear, trigonal planar and trigonal pyramidal with coordination numbers of 2, 3 and 4, respectively. In the structure of 1, neighboring dinuclear units were linked by the CH…Cl intermolecular hydrogen bonds along the three crystallographic axes. In polymer 2, connection between the adjacent chains by the CH…N hydrogen bonds forms a centipede-like skeleton which further extended by the CH…Cl non-covalent intermolecular interactions along the ab and ac planes. DFT calculations on the optimized unit cells of [Cu2(tpmp)X2] (X = Cl and I) which have the same chemical formula in the gas phase, indicate that the observed transitions in the UV–Vis spectra could be mainly assigned to the halogen to ligand charge transfer (XLCT). Topology analysis, Density of States (DOS) spectra, Natural Population Analysis (NPA) as well as second order perturbation theory calculations were also performed on these compounds. Apart from slightly difference between the obtained properties from the DFT calculations which can be attributed to the difference between the electronegativity of the halogen atoms, they have the same electronic properties. This can be assigned to the identical structure of these compounds in the gas phase.

Experimental and quantum computational study of two new bridged copper(II) coordination complexes as possible models for antioxidant superoxide dismutase: Molecular structures, X-band electron paramagnetic spectra and cryogenic magnetic properties

In the present study, we use a dual approach comprising experimental and quantum computational studies of two new bridged copper(II) coordination complexes with NNO donor ligands, viz., [Cu2(μ-sulfato)(L)2(2H2O)]·1.5H2O (1) and [Cu2(μ-succinato)(L)(HL)(H2O)]ClO4 (2), where HL/L = N′-[(E)-pyridin-2-ylmethylidene]benzohydrazide, have been synthesized and characterized using various physico-chemical techniques. Both complexes are structurally characterized using single crystal X-ray diffraction studies. The distances between two copper centers are 3.270(2) Å and 3.178(1) Å, for 1 and 2, respectively. On the basis of quantum computational DFT study, electronic excitations involve transitions mainly from metal-ligand bonding MO’s to the β-LUMO within the dominant Cu atom exhibiting dxy character and to the β-LUMO+1. EPR spectra for these polycrystalline samples were determined for the copper(II) hyperfine structures as well their zero-field splitting which are appropriate for the triplet state of such dimers. Cryomagnetic behavior is consistent with weak antiferromagnetic interactions between the Cu(1)⋯Cu(2) centers in both complexes. The magnetic exchange coupling constant (J) between the Cu(1)⋯Cu(2) centers for 1 and 2 were determined to be J = −1.50(1) and J = −7.7(1)cm−1, respectively. CH⋯π, π⋯π, and lone pair⋯π interactions which have gained attention and their role in bimolecular structure analysis has been recognized. In addition, antioxidant superoxide dismutase activity measurements have showed that homodinuclear complexes give significant scavenging effects against superoxide free radicals. Complex 2 is more antioxidant superoxide dismutase active than 1.

Homo- and Heterodinuclear Head-to-Head or Head-to-Tail Complexes of Rhodium(I) and Iridium(I) with C2,N3 or C8,N9 Bridging Azolato Ligands

Reaction of in situ lithiated N-methylimidazole or 1,5,6-trimethylbenzimidazole with [M(cod)(μ-Cl)]2 (M = Rh, Ir) led to the exclusive formation of the homodinuclear head-to-head complexes [2]–[5], where the metal centers are bridged by two C,N-coordinated azolato ligands. The two metal centers are each coordinated by one cod ligand and either two carbon or two nitrogen donors of the azolato ligands. Access to a heterodinuclear Ir/Rh complex [6] was achieved via the lithiated iridium complex [7] and addition of an equimolar amount of [Rh(cod)(μ-Cl)]2. Deprotonation of caffeine with lithium diisopropylamide and addition of [M(cod)(μ-Cl)]2 (M = Rh, Ir) led to mixtures of the head-to-head (M = Ir: [8H–H]; M = Rh: [9H–H]) and head-to-tail isomers (M = Ir: [8H–T]; M = Rh: [9H–T]) of the homodinuclear complexes. The molecular structures of the homo- and heterodinuclear complexes [3], [5]·2C6H5F, [6]·2C6H5F, and [9H–T]·C4H8O have been determined by X-ray diffraction studies.

Homodinuclear Ni (II) and Cu (II) Schiff base complexes derived from O-vanillin with a pyrazole bridge: Preparation, crystal structures, DNA and protein (BSA) binding, DNA cleavage, molecular docking and cytotoxicity study

Two homodinuclear complexes [Ni2(L)(μ-pz)] (C1) and [Cu2(L)(μ-pz)] (C2) (L = N,N′-bis(3-methoxysalicylidene)-1,3-diamino-2-propanol) were synthesized and characterized by elemental analysis, spectroscopic methods (UV–vis, 1H NMR and IR) and single crystal X-ray crystallography. The crystal structure of both complexes revealed that two metal atoms were doubly bridged by one alkoxo group as an endogenous bridge and one pyrazolate as exogenous bridge. The arrangement around each metal atom was square planar. Interaction of C1 & C2 with HS-DNA and protein (BSA) was investigated by UV–vis and fluorescence spectroscopy. Viscosity measurements, cyclic voltammetry (CV), circular dichroism (CD) and agarose gel electrophoresis were used in the interaction with DNA. The main mode of binding of the complexes with DNA was intercalation and the affinity of C2 (Kb = 9.73 × 105) to DNA was higher than C1 (Kb = 7.41 × 105). These complexes were also investigated in the interaction with BSA. The calculated binding constants of 1478 for C1 and 39012 for C2 revealed that the binuclear complexes strongly bound to protein (BSA). Beside the experimental investigations, the theoretical calculations of molecular docking were performed to obtain detailed binding information of the complexes to DNA and BSA. Finally, cytotoxic activities were assayed by MTT assay. C2 possesses a prominent cytotoxicity against MCF-7 (human breast cancer) (IC50: 19.45 ± 3.61 μM at 24 h; IC50: 17.07 ± 1.88 μM at 48 h) and LNCaP (human prostate cancer) (IC50: 34.55 ± 7.75 μM at 24 h; IC50: 24.93 ± 6.03 μM at 48 h) cell lines.

Groups 1, 2 and Zn(II) Heterodinuclear Catalysts for Epoxide/CO2 Ring-Opening Copolymerization.

A series of heterodinuclear complexes are reported where both Zn(II) and a metal from Group 1 or 2 are chelated by a macrocyclic diphenolate-tetra-amine ligand. The complexes are characterized in the solid state, where relevant by single crystal X-ray crystallography and elemental analysis, and in solution, using NMR spectroscopy and mass spectrometry. The complex synthesis is achieved by reaction of the ligand with diethyl zinc to form the monozinc complex, in situ, followed by subsequent coordination of the second metal; this method enables heterodinuclear conversions >90% as determined by NMR spectroscopy. Alternatively, the same heterodinuclear complexes are accessed by reaction between the two homodinuclear complexes at elevated temperatures for extended periods. These findings suggest that most of the heterodinuclear complexes are the thermodynamic reaction products; the only exception is the Na(I)/Zn(II) complex which is unstable with respect to the homodinuclear counterparts. The catalytic activities and selectivity of the stable heterodinuclear complexes are compared, against each other and the relevant homodinuclear analogues, for the ring-opening copolymerization of CO2 and CHO. Nearly all the heterodinuclear complexes are less active than the dizinc analogues, but the Mg(II)/Zn(II) catalyst is more active. The co-ligand influences the product selectivity, with iodide ligands resulting in cyclic carbonate formation and carboxylate ligands giving a high selectivity for polycarbonate.

CATALASE, CATECHOLASE AND PHENOXAZINONE SYNTHASE-LIKE ACTIVITIES OF HOMODINUCLEAR Co(II), Ni(II), Cu(II) and Zn(II) COMPLEXES INCLUDING OXIME GROUP

Homodinuclear (1) Co(II), (2) Ni(II), (3) Cu(II) and (4) Zn(II) metal complexes containing oxime group were tested for their catalase, catecholase and phenoxazinone synthase-like activity by volumetric and spectrophotometric procedures. Catalase-like activity of the complexes was studied by measuring the evolved dioxygen resulted from the disproportionation reaction of potentially harmful hydrogen peroxide. Catecholase and phenoxazinone synthase-like enzyme activities were followed by the increase in absorbance at 400 and 433 nm resulted from the oxidation reaction of 3,5-di- tert -butylcatechol to 3,5-di- tert -butylquinone and 2-aminophenol to 2-aminophenoxazine-3-one, respectively. Among the studied homodinuclear complexes, complex (3) showed the highest catalytic efficiency for three enzymes tested. Catalytic efficiency of the complexes was found 3>1>4=2 for catalase-like, 3>1>2>4 for catecholase-like and 3>1>4>2 for phenoxazinone synthase-like activity. Relatively higher catalytic activity of the Cu(II) complex is thought to be related to the lower redox potential of Cu(II) ion and better proximity of the chosen substrates with the complex (3).

Ethylene polymerization with novel silicon bridged homo-dinuclear cyanoethyl cyclopentadienyl complexes of titanium and zirconium

Novel homo-dinuclear silicon bridged cyanoethyl cyclopentadienyl complexes of titanium and zirconium (CH3)2Si((η5 − C5H3CH2CH2CN)(C5H5)MCl2)2(M = Ti(1), Zr(2)) were synthesized and developed for the polymerization of ethylene. Compared with their corresponding mononuclear complexes (η5 − C5H4CH2CH2CN)(C5H5)MCl2(M = Ti(3), Zr(4)), the dinuclear complexes had higher catalytic activity. And the polyethylene produced had a higher molecular weight than that obtained with mononuclear catalysts. Effects of conditions on the ethylene polymerization catalyzed by (2)/MAO (methylaluminoxane) were studied in detail. The catalyst showed a very high activity (> 106 g PE/mol Zr·h) under low catalyst concentration and high molar ratio of Al/Zr.

Synthesis, structures, nuclease activity, cytotoxicity, DFT and molecular docking studies of two nitrato bridged homodinuclear (Cu-Cu, Zn-Zn) complexes containing 2,2′-bipyridine and a chalcone derivative

Nitrato briged dinuclear complexes of type [Cu2(L)2(bpy)2(NO3)](NO3)·4H2O, 1 and [Zn2(L)2(bpy)2(NO3)](NO3)·4H2O, 2 (L=deprotonated form of free ligand LH, [1-(2-hydroxyphenyl)-3-(9-anthracenyl) propenone; bpy=2,2′bipyridine] are synthesized and characterized using a battery of physicochemical techniques and X-ray crystallography. A distorted square pyramidal geometry is assigned to them with N2O3 coordination core around the metal ion. The co-ligand L binds the metal ions through its O,O' atoms in anti-syn mode. The metal centers in complexes 1 and 2 are separated via bridging nitrato group at a distance of 6.073Å and 5.635Å respectively. Their structures and absorption spectra are supported by the computational studies using density functional theory (DFT) and TD-DFT. Both complexes exhibit nuclease activity and cleave supercoiled (form I) DNA. The complex 1 preferentially binds major groove of DNA and follows an oxidative pathway whereas complex 2 binds with minor groove of DNA via hydrolytic pathway. Both complexes inhibit topoisomerase I relaxation activity with IC50 values of 7 and 35μM. Molecular docking studies support the groove binding and topoisomerase I binding of the complexes. The complex 1 showed a significant cytotoxicity against HeLa cell lines (a cervical cancer cell lines) in vitro with IC50 value calculated as 2.9±0.021μM as compared to 28.2±0. 044μΜ for complex 2. Complex 2 induces the cell apoptosis at a later-stage as compared to complex 1. The cell apoptosis and topoisomerase inhibition by complexes enable them to be potential candidates as future anticancer drugs.

More about the redox behavior of late transition metal triple-decker complexes with cyclo-triphosphorus

The syntheses of the new triple-decker complexes [(triphos)Co(μ,η3:3-P3)Ru(triphos)](BPh4)2; (CoP3Ru)(BPh4)2, [(triphos)Co(μ,η3:3-P3)Os(triphos)](BPh4)2; (CoP3Os)(BPh4)2 and [(triphos)Ru(μ,η3:3-P3)Ru(triphos)]PF6·(CH3)2CO; (RuP3Ru)PF6·(CH3)2CO, three new members of the [(tripod)M(μ-P3)M′(tripod)]n+ (MP3M′n+) family are described. The structure of the homodinuclear complex (RuP3Ru)PF6·(CH3)2CO is also reported. This latter compound has a structure similar to that of the other members of the series and shows an M⋯M separation among the longest hitherto found in these compounds. An electrochemical study shows that they are stable in various oxidation states with a VEN value ranging between 28 and 34. A reasoning around the redox data shows a progressive shift of two pairs of redox processes, corresponding to the VEN variation 30/31-31/32 and 32/33-33/34, which almost rigidly moves in the cathode direction as the overall charge of the homoelectronic compound decreases.

Electronic Description of the Photophysics of Homo‐ and Heterodinuclear Cyclometallated Iridium and Rhodium Complexes

Photophysical properties of homodinuclear complexes 1 (Ir), 2 (Rh) and heterodinuclear complex 3 (Ir–Rh) have been discussed in solution and in the solid state with the help of quantum chemical calculations by combined DFT‐TDDFT methods. Quantum calculations on these three complexes indicate the participation of metal‐to‐ligand and ligand‐to‐ligand charge transfers to the lowest energy absorptions, and electron transitions from the cyclometallating ligand to the ancillary ligand. The emission behaviour in the solution and solid state confirm the participation of the triplet state as obtained from quantum chemical calculations. It is also noted that the emission behaviour in the mixed‐metal complex is controlled by the iridium metal centre. The ground state electronic interactions between the metal centres studied by electrochemistry are weak interactions, however, energy transfer in the excited state is facile across the bridge.

Structure, luminescence and magnetic properties of an erbium(iii) β-diketonate homodinuclear complex

The photoluminescence properties and field-induced single-molecule-magnetic behavior of a novel erbium(iii) β-diketonate homodinuclear complex, [Er2(nd)6(μ-bpm)] (nd = 2,4-nonanedione and bpm = 2,2′-bipyrimidine), are presented.

Greater than the Sum of Its Parts: A Heterodinuclear Polymerization Catalyst.

Homodinuclear catalysts have good precedent for epoxide and carbon dioxide/anhydride copolymerizations; in contrast, so far pure heterodinuclear catalysts are unknown. The synthesis and properties of a heterodinuclear Zn(II)/Mg(II) complex coordinated by a symmetrical macrocyclic ligand are reported. It shows high polymerization selectivity, control, and significantly greater activity compared to either of the homodinuclear analogues or any combinations of them. Indeed, compared to a 50:50 mixture of the homodinuclear complexes, it shows 5 times (CO2/epoxide) or 40 times (anhydride/epoxide) greater activity.