José L. Priego

MMX polymer chains on surfaces

Fibres of [Ru(2)Br(micro-O(2)CEt)4]n polymer have been isolated on different surfaces under specific conditions, and morphologically characterised by AFM and STM, showing an unexpected helical internal structure.

Synthesis and structure of a new complex of ruthenium containing the tetra(μ-tertbutylbenzoate)diruthenium(II,III) unit

Abstract The compound Ru2Cl(μ-O2CC6H4-p-CMe3)4 has been prepared by the reaction of Ru2Cl(μ-O2CCH3)4 with p-tertbutylbenzoic acid in a water/methanol mixture (1 : 1). The reactions of Ru2Cl(μ-O2CC6H4-p-CMe3)4 with AgBF4, in anhydrous or wet thf, lead to [Ru2(μ-O2CC6H4-p-CMe3)4(thf)2]BF4 and [Ru2(μ-O2CC6H4-p-CMe3)4(thf)2]OH, respectively. The compounds are characterized by elemental analysis, magnetic measurements and spectroscopic techniques. The structure of [Ru2(μ-O2CC6H4-p-CMe3)4(thf)2]OH has been determined by X-ray crystallography. The compound has four bridging p-tertbutylbenzoate ligands with an RuRu distance of 2.260(1) A; the coordination of each ruthenium atom is completed with a thf ligand which is occupying the axial position in the Ru25+ unit.

Time-Dependence Structures of Coordination Network Wires in Solution

We present a mechanochemistry-based procedure to isolate individual chains on surfaces of a ruthenium MMX polymer. After sonication of solutions containing the two building blocks of the mentioned MMX polymer, time-depending structures are formed in the solution. The architecture of the different structures obtained in this process, as a function of the time, is monitored using atomic force microscopy. The resulting structures exhibit uniform subnanometer diameters over microns length, in agreement with the expected diameter for an individual polymer chain. From the atomic force microscope images, we infer a long persistence length for the linear structures. Finally, the effect of the temperature solution in the formation of the different structures is also addressed.

Influence of carboxylic acids on the reactions with chlorotetraacetatodiruthenium(II,III): X-ray crystal structure of [Ru2(μ-O2CC4H3S)4(OPPh3)2]BF4·2H2O

Abstract The reaction of Ru 2 Cl(μ-O 2 CCH 3 ) 4 with indole-2-carboxylic, N -methyl-pyrrole-2-carboxylic, furane-2-carboxylic, thiophene-2-carboxylic and benzofurane-2-carboxylic acids, which contain nitrogen, oxygen or sulphur atoms in the α position with respect to the carboxylate group, leads to compounds of the type Ru 2 Cl(μ-O 2 CR) 4 . In these compounds O,O-coordination of the carboxylate ligands has been found. The analogous reaction with quinoline-2-carboxylic acid (Hquin) gives a disproportionation process with formation of Ru(quin) 3 and Ru 2 (quin) 4 ; in this case, N,O-coordination of the ligand has been observed. The indole-2-carboxylato derivative has a non-polymeric structure, whereas with the other ligands polymeric structures with chlorine atoms bridging Ru 2 5+ units are formed. Treatment of Ru 2 Cl(μ-O 2 CR) 4 in thf or acetone with AgBF 4 gave [Ru 2 (μ-O 2 CR) 4 L 2 ]BF 4 (L = thf, acetone; R = N -methyl-2-pyrrolyl, 2-furyl, 2-thienyl) or [Ru 2 (μ-O 2 CR) 4 ]BF 4 (R = 2-benzofuryl). The axial positions of these compounds can be occupied by OPPh 3 to give the corresponding [Ru 2 (μ-O 2 CR) 4 (OPPh 3 ) 2 ]BF 4 The compounds have been characterized by analytical, spectroscopic and magnetic data. The structure of [Ru 2 (μ-O 2 CC 4 H 3 S) 4 (OPPh 3 ) 2 BF 4 ·2H 2 O has been determined by X-ray crystallography. The dinuclear cation has two ruthenium atoms linked by four bridging thiophene-2-carboxylate ligands and two OPPh 3 ligands coordinated to axial positions, with an Ru—Ru distance of 2.2747(11) A.

First microwave synthesis of multiple metal-metal bond paddlewheel compounds

A green and efficient microwave assisted synthesis of elusive tetrakis(diaryltriazenido)diruthenium(II) complexes was carried out under microwave irradiation. It is a simple, clean, and fast method that proceeds with good yield, in contrast with the poor ones reported in previous syntheses.

Non-polymeric diruthenium(II,III) carboxylates. Crystal structures of [Ru2Cl(µ-O2CCMe3)4(H2O)] and [Ru2Cl(µ-O2CCHMe2)4(thf)](thf = tetrahydrofuran)

The reaction of [Ru2Cl(µ-O2CMe)4] with trimethylacetic acid and isobutyric acid in methanol–water gave [Ru2Cl(µ-O2CCMe3)4(H2O)]1 and [Ru2Cl(µ-O2CCHMe2)4(H2O)]2 respectively. Recrystallization of these compounds from tetrahydrofuran (thf) led to [Ru2Cl(µ-O2CCMe3)4(thf)]3 and [Ru2Cl(µ-O2CCHMe2)4(thf)]4, which lose thf giving [Ru2Cl(µ-O2CCMe3)4]5 and [Ru2Cl(µ-O2CCHMe2)4]6. The complexes were characterized by elemental analysis, IR spectroscopy, conductivity and magnetic measurements; the crystal structures of 1 and 4 were determined by X-ray diffraction methods. Complex 1 has two ruthenium atoms bridged by four trimethylacetato ligands, one axial position being occupied by a chlorine atom and the other by a water molecule. Complex 4 has a similar structure with one chlorine atom and one thf molecule occupying the axial positions. Thus, in both cases the crystal structure determination shows the non-polymeric nature, the first examples for compounds of this type with alkanecarboxylate ligands.

Synthesis and properties of diruthenium (II,III)compounds with trans-2-methyl-2-pentenoate ligand. Crystal structure of Ru2Cl(μ-O2CC(Me)CHEt)4

Abstract The reaction of Ru2Cl(μ-O2CMe)4 with trans-2-methyl-2-pentenoic acid affords the polymeric compound Ru2Cl(μ-O2CC (Me)CHEt)4 (1). This compound has polymeric structure in solid state, but is non-polymeric in solution. The reaction of 1 with OPPh3 in CH2Cl2 solution gives Ru2Cl(μ-O2CC(Me)CHEt)4(OPPh3) (2) supporting the non-polymeric structure of 1 in solution. The reaction of 1 with AgSCN leads to Ru2(μ-O2CC(Me)CHEt)4(SCN) (3) which also has a polymeric structure in solid state. The Ru–Cl bond in 1 was broken with AgBF4 in THF solution, giving [Ru2(μ-O2CC(Me)CHEt)4]BF4(4). All compounds have been characterised by analysis elemental, spectroscopic data and mass and magnetic measurements. The X-ray analysis of 1 shows [Ru2(μ-O2CC(Me)CHEt)4]+ units linked by chloride ions giving linear chains. The Ru–Ru and Ru–Cl distances are 2.281(1) and 2.5705(9) A respectively.

Liquid secondary ion mass spectrometric study of diruthenium(II,III) complexes

Liquid secondary ion mass spectra of diruthenium(II,III) compounds of the type Ru2Cl(μ-O2CCMe3)4(H2O) (1), Ru2Cl(μ-O2CCHMe2)4(thf) (2), Ru2X(μ-O2CR)4 (X Cl, R CMe3 (3), CHMe2 (4), CHEt2 (5), CHMePh (6), Me (9), C6H4-p-CMe3 (10); X SCN, RCMe3 (7), CHEt2 (8)), Ru2X(μ-O2CR)4(OPPh3) (XCl, RCHMe2 (11), CMe3 (12); XSCN, RCMe3 (13)) and Ru2Cl(μ-NHOCR)4 (RCMe3 (14), C6H4-p-CMe3 (15)) have been studied. The positive ion of Ru2X(μ-O2CR)4 (XCl, SCN) compounds typically contains intact M+ or [M + H]+ cations. For the complexes Ru2X(μ-O2CR)4(OPPh3) (XCl, SCN) no molecular peaks were found, but the detected fragment clearly confirms the proposed stoichiometries. MS/MS experiments have been carried out to establish general fragmentation pathways of these complexes. Also, clustering processes — as a result of ion molecule reactions which give [Ru2(μ-O2CR)4XRu2(μ-O2CR)4]+ (XCl, SCN) — have been found. These results show that the liquid secondary ion mass spectrometry (LSIMS) technique is useful to establish the structure and molecular formula of diruthenium(II,III) compounds, even when the molecular peaks are not observed. This technique also informs us on the polymeric/non-polymeric nature of this type of complex.

Tert-butylbenzamidate diruthenium(II, III) compounds. Crystal structure of [Ru2(μ-HNOCC6H4-p-CMe3)4(OPPh3)2]BF4

Abstract The reaction between Ru2Cl(μ-O2CCH3)4 and molten p-tert-butylbenzamide led to the formation of Ru2Cl(μ-HNOCC6H4-p-CMe3)4. The polymeric structure of this insoluble compound was broken with AgBF4, in anhydrous thf, giving [Ru2(μ-HNOCC6 H4-p-CMe3)4(thf)2]BF4. The reaction of this cationic complex with OPPh3 gave [Ru2(μ-HNOCC6H4-p-CMe3)4(OPPh3)2]BF4. The compounds have been characterized by elemental analysis, spectroscopic data and magnetic measurements and the crystal structure of [Ru2(μ-HNOCC6H4-p-CMe3)4(OPPh3)2]BF4 was determined by X-ray crystallography. The asymmetric unit is composed of halves of two different crystallographically independent centrosymmetric cations. Each ruthenium(II,III) dimer is bonded to four bridging p-tert-butylbenzamidate ligands and to two axial triphenylphosphine oxide molecules. The RuRu distances in the two dimeric cations of the unit cell are 2.281(2) and 2.280(2) A. The compound has a non-polar 2 : 2 arrangement of the tert-butylbenzamidate ligands.

Synthesis of diruthenium(II,III) amidate compounds. Crystal structure of [Ru2(μ-HNOCC4H3S)4(thf)2]SbF6·0.5cyclohexane

Abstract The reaction of Ru2Cl(μ-O2CMe)4 with amides in 2-methoxyethanol affords the compounds Ru2Cl(μ-HNOCR)4 [R=C6H3-3,5-(OMe)2 (1), C6H4p-OMe (2), C6H4p-CMe3 (3), C4H3S (4), cyclo-C6H11 (5), CMe3 (6)]. The reaction of 1–6 with AgBF4 and AgSbF6 gives [Ru2(μ-HNOCR)4(thf)2]BF4 [R=C6H3-3,5-(OMe)2 (7), C6H4p-OMe (8), C6H4p-CMe3 (9), C4H3S (10), cyclo-C6H11 (11), CMe3 (12)] and [Ru2(μ-HNOCR)4(thf)2]SbF6 [R=C6H3-3,5-(OMe)2 (13), C6H4p-OMe (14), C6H4p-CMe3 (15), C4H3S (16), cyclo-C6H11 (17), CMe3 (18)], respectively. The structure of complex 16·0.5cyclohexane has been determined by X-ray crystallography. The RuRu bond distance in the [Ru2(μ-HNOCC4H3S)4(thf)2]+ unit is 2.286(2) A. A magnetic study, in the 2–300 K temperature range, of the compounds is described. Complexes 1–18 show a large zero-field splitting which varies from 43 to 71 cm−1. These complexes also show a weak, but not negligible intermolecular antiferromagnetic coupling (zJ from −0.1 to −2.9 cm−1). These antiferromagnetic exchanges have not been observed previously in the amidate complexes.