Syntheses, Structures, and Magnetic Properties of Mixed-Valent Diruthenium(II,III) Diphosphonates with Discrete and One-Dimensional Structures

Homo-valent diruthenium(II,II) carbonates Na4[Ru2(CO3)4]·10H2O: synthesis, structure, properties, and calculation

Homo-valent diruthenium(II,II) carbonates have been underexplored hitherto. This paper reports the synthesis and crystal structure of a diruthenium(II,II) compound, Na₄Ru₂(CO₃)₄·10H₂O (1). It has a two-dimensional structure in which the paddle-wheel diruthenium units of Ru₂(CO₃)₄^4- are cross-linked through the carbonate groups. The investigation of the primary magnetic properties and theoretical studies with density functional theory (DFT) reveal that weak antiferromagnetic interactions are propagated between the Ru₂ units which contain two unpaired electrons in an electron configuration σ²π⁴δ²π*²δ*² with a ground state S = 1. According to Raman spectrum measurements combined with theoretical calculations, the strong peak at 356 cm^-1 in the small-wavenumber region was assigned to the stretching of the Ru-Ru double bonds.

Multiple MMCT properties of the diruthenium-based cyanido-bridged complex RuVI2-NC-RuII-CN-RuVI2

The diruthenium-based linear mixed valence complex trans-[Ru₂(ap)₄-NC-Ru(DMAP)₄-CN-Ru₂(ap)₄][PF₆]₂ (12+[PF6]2) (ap = 2-anilinopyridinate, DMAP = 4-dimethylaminopyridine) and its two-electron oxidation product 14+[PF6]4 have been synthesized and fully characterized. The investigation reveals that complex 12+ displays a single MMCT transition, whereas complex 14+ has three identified MMCT transitions (MMCT-1, MMCT-2 and MMCT-3) upon oxidation. Interestingly, MMCT-2 in complex 14+ might result from the transition from the Ru^III-NC-Ru^II-CN-Ru^III component, which is composed of the central Ru^II and its two neighboring Ru^III atoms from the cluster RuVI2 units, to both the terminal Ru^III atoms of the same cluster RuVI2 units, which is supported by the TDDFT calculations.

A Ru diphosphonato complex with a metal-metal bond for water oxidation

Unlike [Ru2(μ-O2CCH3)4], the structurally analogous water-soluble RuII,III2 diphosphonato complex K3[Ru2(hedp)2(H2O)2] (K3·1) is only involved in stoichiometric water oxidation with a maximum 67% O2 yield under CAN/HNO3 solution (pH 1.0) for 2.5 h. The water oxidation mechanism and intermediate products were ascertained by UV-vis, ESI-MS and DFT calculation.

Metal phosphonates incorporating metalloligands: assembly, structures and properties

This feature article summarizes the current status of metal–metalloligand phosphonates including the synthetic strategies, crystal structures and properties. Future challenges in this field are discussed.

Towards a new type of heterometallic system based on a paddle-wheel Ru2 dimer: first results derived from the use of a high spin diruthenium(iii,iii) building block

Heterometallic diruthenium(iii,iii) compound shows a two-step relaxation and order below 14 K with a coercive field of 24.9 kOe at 1.8 K.

Chlorine and temperature directed self-assembly of Mg-Ru2(ii,iii) carbonates and particle size dependent magnetic properties

A series of heterometallic magnesium diruthenium(ii,iii) carbonates, namely K{Mg(H2O)6}2[Ru2(CO3)4Cl2]·4H2O (1), K2[{Mg(H2O)4}2Ru2(CO3)4(H2O)Cl]Cl2·2H2O (2), K[Mg(H2O)5Ru2(CO3)4]·5H2O (3) and K[Mg(H2O)4Ru2(CO3)4]·H2O (4), were synthesized from the reaction of Ru2(CO3)4(3-) and Mg(2+) in aqueous solution. Compound 1 is composed of ionic crystals with the Ru2(CO3)4Cl2(5-) : Mg(H2O)6(2+) : K(+) ratio of 1 : 2 : 1. Compound 2 consists of two dimensional layer structures, in which each octahedral environment Mg(H2O)4(2+) bonds to two [Ru2(CO3)4(H2O)Cl](4-) units in a cis manner forming a neutral square-grid layer {Mg(H2O)4Ru2(CO3)4(H2O)Cl}n. For compound 3, one water molecule of each Mg(H2O)6(2+) is substituted by an oxygen atom of Ru2(CO3)4(3-) forming [Mg(H2O)5Ru2(CO3)4](-), and then the neighboring Ru2 dimers are linked together by the rest of the two oxygen atoms of carbonates to form a layer structure {Mg(H2O)5Ru2(CO3)4}n(n-). In compound 4, the neighboring squared-grid layers {Ru2(CO3)4}n(3n-), similar to those in compound 3, are linked by each octahedral environment Mg(H2O)4(2+) in a cis manner forming the three-dimensional network {Mg(H2O)4Ru2(CO3)4}n(n-). Compound 3 shows ferromagnetic coupling between Ru2 dimers, and a long-range ordering is observed below 3.8 K. Compound 4 displays a magnetic ordering below 3.5 K, and a systematic study of the size-dependent magnetic properties of compound 4 reveals that the coercivity of 4 has been improved with reduced sample particle size from the micrometer to the nanometer scale.

Crystal structure of poly[[di-μ2-aqua-aquasodium] 4-amino-3,5,6-trichloropyridine-2-carboxylate trihydrate], the sodium salt of the herbicide picloram

The trihydrated sodium salt of the herbicide picloram comprises a cationic μ₂-aqua-bridged chain structure that is linked to the picloramate anions through amine N—H⋯O and water O—H⋯O and O—H⋯N hydrogen bonds.

In the structure of the title complex, {[Na(H₂O)₃](C₆H₂Cl₃N₂O₂)·3H₂O}_n, the sodium salt of the herbicide picloram, the cation adopts a polymeric chain structure, based on μ₂-aqua-bridged NaO₅ trigonal–bipyramidal complex units which have, in addition, a singly bonded water mol­ecule. Each of the bridges within the chain, which extends parallel to the a axis, is centrosymmetric, with Na⋯Na separations of 3.4807 (16) and 3.5109 (16) Å. In the crystal, there are three water mol­ecules of solvation and these, as well as the coordinating water mol­ecules and the amino group of the 4-amino-3,5,6-tri­chloro­picolinate anion, are involved in extensive inter-species hydrogen-bonding inter­actions with carboxyl and water O atoms, as well as the pyridine N atom. Among these associations is a centrosymmetric cyclic tetra­water R₄⁴(8) motif, resulting in an overall three-dimensional structure.

Multidimensional (0D to 3D) Alkaline-Earth Metal Diphosphonates: Synthesis, Structural Diversity, and Luminescence Properties

A series of new alkaline-earth metal diphosphonate frameworks were successfully synthesized under solvothermal reaction condition (160 °C, 3 d) using 1-hydroxyethylidene-1,1-diphosphonic acid (CH3C(OH)(H2PO3)2, hedpH4) as a diphosphonate building block and Mg(II), Ca(II), Sr(II), or Ba(II) ions as alkaline-earth metal ion centers in water, dimethylformamide, and/or EtOH media. These diphosphonate frameworks, (H2NMe2)4[Mg(hedpH2)3]·3H2O (1), (H2NMe2)2[Ca(hedpH2)2] (2), (H2NMe2)2[Sr3(hedpH2)4(H2O)2] (3), and [Ba3(hedpH2)3]·H2O (4) exhibited interesting structural topologies (zero-, one-, two-, and three-dimensional (0D, 1D, 2D, and 3D, respectively)), which are mainly depending on the metal ions and the solvents used in the synthesis. The single-crystal analysis of these newly synthesized compounds revealed that 1 was a 0D molecule, 2 has 1D chains, 3 was a 3D molecule, and 4 has 2D layers. All compounds were further characterized using thermogravimetric analysis, solid-state (31)P NMR, powder X-ray diffraction analysis, UV-vis spectra, and infrared spectroscopy. In addition, Eu(III)- and Tb(III)-doped compounds of 1-4, namely, (H2NMe2)4[Ln(x)Mg(1-x)(hedpH2)2(hedpH(2-x))]·3H2O (1Ln), (H2NMe2)2[Ln(x)Ca(1-x)(hedpH2)(hedpH(2-x))] (2Ln), (H2NMe2)2[Ln(x)Sr(3-x)(hedpH2)3(hedpH(2-x))(H2O)2] (3Ln), and [Ln(x)Ba(3-x)(hedpH2)2(hedpH(2-x))]·H2O (4Ln) (where Ln = Eu, Tb), were synthesized, and their photoluminescence properties were studied. The quantum yield of 1Eu-4Eu was measured with reference to commercial red phosphor, Y2O2S:Eu(3+) (YE), and the quantum yield of terbium-doped compounds 1Tb-4Tb was measured with reference to commercial green-emitting phosphor CeMgAl10O17:Tb(3+). Interestingly, the compound 2Eu showed very high quantum yield of 92.2%, which is better than that of the reference commercial red phosphor, YE (90.8%).

Isomeric chain structures of {[Mn(H₂O)₄]₂Ru₂(CO₃)₄Br₂}n(n-): syntheses, structural diversity and magnetic properties

The self-assembly of Ru2(CO3)4(3-) paddle-wheel precursors and Mn(2+) ions in aqueous solution yields various carbonate complexes. With appropriate selection of the synthetic conditions, we are able to intentionally tune the composition and structure of Mn-Ru2-carbonate assemblies to form infinite chain structural complexes, e.g., K[{Mn(H2O)4}2Ru2(CO3)4Br2]·H2O (1) and H[{Mn(H2O)4}2Ru2(CO3)4Br2]·6H2O (2). Complexes 1 and 2 are obtained at different temperatures (25 °C for 1 and 5 °C for 2, respectively), and their crystal structures consist of brick-wall stacked chains, in which neighboring Ru2(CO3)4Br2(5-) units are linked by two disubstituted octahedral Mn(H2O)4(2+) in a cis manner, resulting in two isomeric (twisted and zigzag) negative double-chain α- and β-{[Mn(H2O)4]2Ru2(CO3)4Br2}n(n-). The magnetic properties of complexes 1 and 2 were highly characterized. The alternating current (AC) susceptibility analysis of complex 1 reveals a two-step magnetism transition at T1 = 5.0 K and T2 = 2.6 K, respectively. Complex 2 exhibits metamagnetism behavior, with a transition field H(C) = ~1.2 kOe at 2.0 K.

Diphosphates and diphosphonates in polyoxometalate chemistry

In the wide area of polyoxometalate (POM) chemistry, diphosphate/diphosphonate-based POMs represent a more recent area of study. However, in this short time it has emerged to become very dynamic, as shown by the wide variety of compounds reported. Ever since the discovery of the first polyoxotungstate framework constructed from diphosph(on)ate ligands, a widespread investigation on the preparative chemistry and properties of such compounds has followed. The main focus of such a study is based on factors such as the oxidation state of the metal, the effect of pH and temperature during synthesis, and the presence of different functional groups on the diphosphonate. In this review we discuss in detail all diphosphate/diphosphonate-based POMs, beginning with early developments, subsequent growth in interest, and finally focusing on the very latest developments.

A novel inorganic-organic hybrid borate, poly{[Na(2)(C(4)H(2)O(4))(H(3)BO(3))(H(2)O)(4)]·H(3)BO(3)}

The structure of the title compound, catena-poly[[[di-μ-aqua-μ-fumarato-μ-(boric acid)-disodium]-di-μ-aqua] boric acid monosolvate], contains two crystallographically independent Na(+) cations, each being six-coordinated by one fumarate O atom, one boric acid O atom and four water O atoms in a distorted octa-hedral geometry. Adjacent [NaO(2)(OH(2))(4)] units share edges and are linked into chains propagating parallel to [100]. The free boric acid mol-ecules are connected to the chains through strong inter-molecular O-H⋯O hydrogen bonds. Additional O-H⋯O hydrogen bonds between the water mol-ecules, the free and coordinated boric acid mol-ecules and the fumarate anion lead to the formation of a three-dimensional supra-molecular structure. With the exception of the two water mol-ecules, all other atoms lie on mirror planes.

Redetermination of the borax structure from laboratory X-ray data at 145 K

The title compound, sodium tetraborate decahydrate (mineral name: borax), Na₂[B₄O₅(OH)₄]·8H₂O, has been studied previously using X-ray [Morimoto (1956). Miner. J.2, 1–18] and neutron [Levy & Lisensky (1978). Acta Cryst. B34, 3502–3510] diffraction data. The structure contains tetra­borate anions [B₄O₅(OH)₄]²⁻ with twofold rotation symmetry, which form hydrogen-bonded chains, and [Na(H₂O)₆] octa­hedra that form zigzag chains [Na(H₂O)_4/2(H₂O)_2/1]. The O—H bond distances obtained from the present redetermination at 145 K are shorter than those in the neutron study by an average of 0.127 (19) Å.

Cyanide-Bridged Mn(III)−Fe(III) Bimetallic Complexes Based on the Pentacyano(1-methylimidazole)ferrate(III) Building Block: Structure and Magnetic Characterizations

Seven cyanide-bridged bimetallic complexes have been synthesized by the reaction of [Fe(1-CH3im)(CN)5]2- with Mn(III) Schiff base complexes. Their crystal structure and magnetic properties have been characterized. Five complexes, [Mn2(5-Brsalen)2Fe(CN)5(1-CH3im)] x H2O (1), [Mn2(5-Clsalen)2(H2O)2Fe(CN)5(1-CH3im)] x H2O (2), [Mn2(5-Clsaltn)2(H2O)2Fe(CN)5(1-CH3im)] (3), [Mn2(5-Clsaltmen)2(H2O)2Fe(CN)5(1-CH3im)] x H2O (4), and [Mn2(5-Brsaltmen)2(H2O)2Fe(CN)5(1-CH3im)] x CH3OH (5), are neutral and trinuclear with two [Mn(SB)]+ (SB2- = Schiff base ligands) and one [Fe(1-CH3im)(CN)5]2-. Complex {[Et4N][Mn(acacen)Fe(CN)5(1-CH3im)]}n x 6nH2O (6) is one-dimensional with alternate [Mn(acacen)]+ and [Fe(CN)5(1-CH3im)]2- units. The two-dimensional complex {[Mn4(saltmen)4Fe(CN)5(1-CH3im)]}n[ClO4]2n x 9nH2O (7) consists of Mn4Fe units which are further connected by the phenoxo oxygen atoms. Magnetic studies show the presence of ferromagnetic Mn(III)-Fe(III) coupling in the trinuclear compounds with the magnetic coupling constant (J) ranging from 4.5 to 6.0 cm-1, based on the Hamiltonian H = -2JSFe(SMn(1) + SMn(2)). Antiferromagnetic interaction has been observed in complex 6, whereas ferromagnetic coupling occurs in complex 7. Complexes 6 and 7 exhibit long-range magnetic ordering with a TN value of 4.0 K for 6 and Tc of 4.8 K for 7. Complex 6 shows metamagnetic behavior at 2 K, and complex 7 possesses a hysteresis loop with a coercive field of 500 Oe, typical of a soft ferromagnet.

Template- and pH-Directed Assembly of Diruthenium Diphosphonates with Different Topologies and Oxidation States

In the presence of organic templates, six diruthenium diphosphonates, namely, [H3N(CH2)3NH3]2[Ru2(hedp)2] (1), [H3N(CH2)4NH3]2[Ru2(hedp)2].4H2O (2), [H3N(CH2)5NH3]2[Ru2(hedp)2].4H2O (3), [H3N(CH2)3NH3][Ru2(hedp)(hedpH)].H2O (4), [H3N(CH2)4NH3][Ru2(hedpH(0.5))2].2H2O (5), and [H3N(CH2)5NH3]2[Ru2(hedp)2][Ru2(hedpH)2]] (6) [hedp = 1-hydroxyethylidenediphosphonate, CH3C(OH)(PO3)2] have been synthesized under hydrothermal conditions. Compounds 1-3 contain homovalent paddlewheel cores of Ru2(II,II)(hedp)2(4-) that are connected through edge-sharing of the [RuO5Ru] octahedra, resulting in infinite linear chains. Compounds 4-6 contain mixed-valent diruthenium(II,III) phosphonate paddlewheel cores of Ru2(II,III)(hedpH(n))2(3-2n)- that are connected by phosphonate oxygen atoms, forming distorted square-grid layers in 4 and 6 or a kagomé lattice in 5. Both the templates and the pH values are found to play important roles in directing the final products with particular topologies and oxidation states of the diruthenium unit. The magnetic studies show that weak antiferromagentic interactions are propagated between the homovalent diruthenium units in compounds 1-3. For compounds 4-6, weak ferromagnetic interactions are observed.

Mixed-Valent Diruthenium Diphosphonate with Kagomé Structure

This paper reports the first example of diruthenium phosphonate with kagomé structure, namely, [NH3(CH2)4NH3][Ru2(hedpH(0.5))2].2H2O (hedp = 1-hydroxyethylidenediphosphonate). The compound contains kagomé layers that are linked by very strong hydrogen bonds into a nanoscale kagomé structure. Ferromagnetic interactions are mediated between the paramagnetic diruthenium units.