Synthesis and electrocatalytic reactivity for water oxidation of two cerium complexes

Two cerium complexes with and without manganese ion, [MnCe₄(dipic)₆(H₂O)₂₀][Ce(dipic)₃]₂·7H₂O (dipic = dipicolinate) (1) and [Ce₂(H₂O)₄(O₂CMe)₆][Ce(H₂O)₄(NO₃)₂(O₂CMe)]₂·2H₂O·2MeOH (2), have been prepared, and their electrocatalytic reactivity for water oxidation has been investigated. Compound 1 is a heterometallic 3d-4f compound which possesses four Ce(IV) ions, two Ce(III) ions, and one Mn(II). Compound 2 is composed of three neutral parts, one of which is a dinuclear cerium molecule lying on an inversion center, and the other two are symmetric monomer units; the four cerium ions in 2 are all Ce(III). Electrochemical studies of 1 and 2 show that 1 can catalyze water oxidation at the potential ~1.5 V with an overpotential of ca. 900 mV versus NHE. Control potential electrolysis (CPE) experiments at 1.50 V of 1 displayed a stable current density of 2.5 mA/cm², and the calculated Faradaic efficiency is 60%. However, no electrocatalytic reactivity was observed for 2. By comparison experiments, it was found that the electrocatalysis of 1 may result from the cooperative catalytic effect of the 4f cerium ion and 3d transition metal manganese ion.     

Two 3d‐4f Heterometallic Coordination Polymers of Macrocyclic Oxamide with Benzotriazole‐5‐carboxylate Co‐ligand: Syntheses,Crystal Structures and Magnetic Properties

Two heterometallic 3d–4f coordination polymers, [Gd(CuL)₂(Hbtca)(btca)(H₂O)] · 2H₂O ( 1 ) and [Er(CuL)₂(Hbtca)(btca)(H₂O)] · H₂O · CH₃OH ( 2 ) (CuL, H₂L = 2,3‐dioxo‐5,6,14,15‐dibenzo‐1,4,8,12‐tetraazacyclo‐pentadeca‐7,13‐dien; H₂btca = benzotriazole‐5‐carboxylic acid) were synthesized by solvothermal methods and characterized by single‐crystal X‐ray diffraction. Complexes 1 and 2 exhibit a double‐strand meso‐helical chain structures formed by [Ln^IIICu^II₂] (Ln^III = Gd, Er) units by oxamide and benzotriazole‐5‐carboxylate bridges. They are isomorphic except that one free water molecule of 1 is replaced by a methanol molecule. All 1D chains are further interlinked by hydrogen bonds resulting in a 3D supramolecular architecture. The magnetic properties of the compound 1 and 2 are also discussed.     

A Ag-La heterometallic 2D layer based on mono-lacunary Keggin polyoxometalate: Synthesis,structure, and photocatalytic property

A new two-dimensional (2D) purely inorganic 4d-4f heterometallic compound [La(H₂O)₈][Ag{La(H₂O)₆}₂{SiW₁₁La(H₂O)₄O₃₉}₂]·13H₂O (1), based on mono-lacunary Keggin-type {α-SiW₁₁O₃₉} cluster (abbreviated to SiW₁₁), was conventional synthesized and characterized by elemental analysis, IR, TG, and single crystal X-ray diffraction. In compound 1, two mono-substituted {SiW₁₁La(H₂O)₄O₃₉}₂ clusters (abbreviated to SiW₁₁La) polymerize together to form a dimer. And the dimers are linked by Ag⁺ and La³⁺ heterometallic cations displaying a 2D network. Furthermore, the photocatalytic experiment indicates that the title compound presents excellent photocatalytic activity towards degradation of rhodamine B (RhB) dye.     

Synthesis,Structure and Luminescence of Cd3Cu2 and Cd2Ni4 Heteronuclear Complexes with Macrocyclic Oxamide and 5‐Sulfosalicylicate

Two novel heteronuclear complexes [Cd₃(SSAL)₂(CuL)₂(H₂O)₄]_n ( 1 ) and [Cd₂(HSSAL)₂(NiL)₄] · 4H₂O ( 2 ) were synthesized and structurally determined, where SSAL is the fully deprotonated 5‐sulfosalicylic ion (CuL and NiL, H₂L = 2,3‐dioxo‐5,6,14,15‐dibenzo‐1,4,8,12‐tetraazacyclopentadeca‐7,13‐diene). Compound 1 displays a 1D ladder‐like chain and all these chains are further interlinked through hydrogen bonds resulting in a 2D architecture. The structure of 2 consists of 5‐sulfosalicylates and an oxamido‐bridge and is arranged in butterfly‐like hexanuclear molecules. The luminescent properties of compounds 1 and 2 are also discussed.     

Stereochemistry of heterometallic platinum clusters

Heterometallic platinum complexes cover a huge field, as shown by a recent survey covering the crystallographic and structural data of almost 1500 examples. About 5% of those complexes exists as isomers and are summarized in this review; except one cis-trans example, the remainder are distortion isomers. These are discussed in terms of the coordination about the platinum atom, and correlations are drawn between donor atom, bond lengths and interbond angles, with attention to trans effect and metal-metal bonds. Distortion isomers, differing only by degree of distortion in Pt–L and Pt–M distances and L–M–L bond angles, spread over a wide range of oxidation states of platinum: zero, +1, +2 (most common) and +4. The mean Pt–Pt bond distance elongate with increase in oxidation state of platinum: 2.705 Å (Pt(0)–Pt(0)) < 2.720 Å (Pt(I)–Pt(I)) < 2.773 Å (Pt(II)–Pt(II)). The shortest mean Pt–M bond distances are: Pt(0)–Ga = 2.37 Å; Pt(I) = Au 2.697 Å, Pt(II)–Fe = 2.625 Å and Pt(IV)–Sn, 2.580 Å.     

A series of multinuclear homo- and heterometallic complexes with bridging tellurolato ligands derived from [CpIr(CO)(TeTol)2] (Cp = η-C5Me5, Tol = p-tolyl)

Reactions of [Cp^∗Ir(CO)(TeTol)₂] (1; Tol = p-tolyl) with certain organometallic Pd(II), Pt(II), Ir(III), Rh(III), and Ru(II) species afforded IrPd, IrPt, IrPt₂, Ir₂, IrRh, IrRu₃, and IrRu complexes having tellurolato-bridged dinuclear or trinuclear cores. This finding demonstrates that 1 is a versatile precursor to synthesize a variety of multinuclear homo- and heterometallic μ-tellurolato complexes, whose chemistry is still less advanced as compared with that of μ-thiolato complexes.     

Heterobimetallic thiocyanato-bridged coordination polymers based on [Hg(SCN)4]: Synthesis, crystal structure, magnetic properties and ESR studies

Three new M/Hg bimetallic thiocyanato-bridged coordination polymers; [Hg(SCN)₄Ni(Im)₃]_∞1, [Hg(SCN)₄Mn(Im)₂]_∞2, and [Hg(SCN)₄Cu(Me-Im)₂ Hg(SCN)₄Cu(Me-Im)₄]_∞3, (Im=imidazole, Me-Im=N-methyl-imidazole), have been synthesized and characterized by means of elemental analysis, ESR, and single-crystal X-ray. X-ray diffraction analysis reveals that these three complexes all form 3D network structure, and their structures all contain a thiocyanato-bridged Hg?M?Hg chain (M=Mn, Ni, Cu) in which the metal and mercury centers exhibit different coordination environments. In complex 1, the [Hg(SCN)₄]²⁻ anion connects three [Ni(Im)₃]²⁺ using three SCN ligands giving rise to a 3D structure, and in complex 2, four SCN ligands bridge [Hg(SCN)₄]²⁻ and [Mn(Im)₂]²⁺ to form a 3D structure. The structure of 3 contains two copper atoms with distinct coordination environment; one is coordinated by four N-methyl-imidazole ligands and two axially elongated SCN groups, and another by four SCN groups (two elongated) and two N-methyl-imidazole ligands. The magnetic property of complex 1 has been investigated. The spin state structure in hetermetallic NiHgNi systems of complex 1 is irregular. The ESR spectra results of complex 3 demonstrate Cu²⁺ ion lie on octahedral environment.     

Synthesis,Magnetism, and Thermostability of a Series of Two‐Dimensional Lanthanide–Nickel Heterometallic Coordination Polymers

A series of Ln–Ni heterometallic coordination polymers, {[Ln₂Ni(MIDA)₄(H₂O)₆](H₂O)₄} (Ln = La ( 1 ), Ce ( 2 ), Pr ( 3 ), and Nd ( 4 ); H₂MIDA = N‐methyl‐iminodiacetic acid), were obtained under hydrothermal conditions. Single crystal X‐ray diffraction revealed that they feature two‐dimensional isomorphic frameworks, which could be viewed as the construction by one‐dimensional {Ln}_n chain connecting by bridges of [Ni(MIDA)₂]². The magnetic measurements reveal that compounds 2 – 4 exhibit antiferromagnetic properties. TGA results indicate compounds 1 and 4 have good thermostability with the critical temperature of 375 °C.     

Modern aspects on tri- and tetranuclear cluster complexes supported by phosphido bridges

This report on small cluster complexes with metal-metal bonds in the field of coordination chemistry documents results in the following scientific areas. (1) Systematic synthetic routes via ditransition metal carbonyl derivative of manganese and rhenium (group 7) to functionalizedtriangulo- andtetrahedro-clusters including structural characterization, (2) Dynamic properties of mono- and diauration isomers like M₂(μ-AuPR₃)(μ-PCyH)(CO)₈/M₂(μ-H)(μ₃-PCy(AuPR₃))(CO)₈ (isomerization) and M₂(μ-AuPR₃)₂(μ₄-PCy)(CO)₈/M₂(μ-AuPR₃)(μ₃-PCy(AuPR₃))(CO)₈ (M = Mn, Re; R = organic residue) (rearrangement and valence isomerization) and MM’(μ-H)(μ-PCy₂)(μ₄-PCy(AuPR₃))(CO)₆ (M = M’, M ≠ M’) (topomerization) going from one to the other homologue and the kinetic study of isomerization in the framework Re₂(AuPCy₃)₂(μ-PMeN₂(μ-C(Bu)O)(CO)₆, (3) Correlations of chirality transfer in diastereomerictetrahedro-clusters Re₂(M¹PR₃)₂(μ-PCy₂)(CO)₇(η¹-L*) (M¹ = coin metals, L* = chiral ligand as (+) or (-) prolinate, for example) from CD data. These selected contributions will be discussed to answer the question “Do small cluster complexes remain as a future challenge in cluster chemistry?”