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The complete series of [Ru2Cl(Dp-FPhF)x(O2CCH3)4−x] (x = 1–4; Dp-FPhF− = N,N′-bis(4-fluorophenyl)formamidinate) compounds, has been prepared and characterized by a multi-technique approach, including single crystal X-ray diffraction. A careful study of the different methodologies has allowed us to prepare four compounds with good yields and without an inert atmosphere or further purification. Specifically, [Ru2Cl(Dp-FPhF)(O2CCH3)3] (1) was obtained using an ultrasound-assisted (USS) method, while [Ru2Cl(Dp-FPhF)4] (4) was prepared by microwave assisted solvothermal synthesis (MWS). The intermediate substitution products cis-[Ru2Cl(Dp-FPhF)2(O2CCH3)2] (2) and [Ru2Cl(Dp-FPhF)3(O2CCH3)] (3) have been prepared by conventional heating, controlling the molar ratio of the starting materials. ESI-MS and infrared spectroscopy were used to follow all the reactions and permitted a qualitative evaluation of the axial reactivity in this series. Magnetic and absorption measurements confirmed a high spin σ2π4δ2(π*δ*)3 electronic configuration in all cases. However, the effect of the gradual modification of the electronic density in the diruthenium core markedly affects other properties. The cyclic voltammograms of the compounds show a strong decrease in the one electron oxidation potential and an increase in the reduction potential in the series from 1 to 4. Furthermore, despite their paramagnetic nature, 1H- and 19F-NMR spectra were recorded, and a correlation between the paramagnetic shift of the signals and the substitution degree of the diruthenium species was observed. These results provide a comprehensive guide to synthesise and understand the effects of equatorial ligand substitution on the properties of Ru25+ compounds. [ABSTRACT FROM AUTHOR]

We report herein on three zigzag one-dimensional coordination polymers of {[Ru2 (µ-NHOCR)4](µ-SCN)}n (R = o-Me-C6H4 (2), m-Me-C6H4 (3), p-Me-C6H4 (4)) formula. These new compounds have been obtained by reaction of the corresponding [Ru2(µ-NHOR)4(THF)2](BF4) complex with (NBu4)(SCN) under different synthetic conditions. The crystal structure of [Ru2 (µ-NHOCC6H4-o-Me)4(THF)2](BF4) (1), 2 and 3 are presented. A cis-(2,2) arrangement of the amidate ligands of the [Ru2(µ-NHOCR)4]+ units is observed in all cases. Interestingly, the structures of 2 and 3 show linkage isomerism in alternated tetraamidatodiruthenium units whose axial positions are occupied by the same type of donor atom of the SCN ligands. This results in zigzag chains with a Ru-S-C angle of 98.97ffi and Ru-N-C angle of 169.36ffi in the case of 2 and 97.99ffi and 159.26ffi, respectively, in the case of 3. The magnetic data obtained for 2-4 are indicative of a 24ffi2(*ffi*)3 ground state (S = 3/2) and a large zero-field splitting (ZFS) in all cases (D = 54.57, 62.72 and 43.00 cm-1 for 2-4, respectively). Similar small antiferromagnetic interactions between diruthenium units (zJ = 0.93, 0.79 and 1.11 cm1 for 2-4, respectively) are estimated for all the polymers, suggesting an analogous zigzag arrangement of the chains for 4. [ABSTRACT FROM AUTHOR]

Microwave and solvothermal activation processes have been explored as tools for the preparation of various nickel and ruthenium complexes. Different reaction conditions are tested using ethanol or water as solvents. Three nickel derivatives, [Ni(9-atc) 2 (OH 2 ) 2 (py) 2 ]·2EtOH ( 1 ), [Ni 2 (9-atc) 4 (OH 2 )(py) 4 ]·2H 2 O ( 2 ·2H 2 O), and [Ni 2 (9-atc) 4 (py) 2 ] ( 3 ), and two diruthenium compounds, {[Ru 2 Cl(9-atc) 4 ]·2H 2 O} n ( 4 ) and [Ru 2 (9-atc) 4 (EtOH) 2 ]·2EtOH ( 5 ), are obtained. The crystal structure determination of complexes 1 – 3 and 5 is also described. Compound 1 displays a 1D extended supramolecular structure with hydrogen bonds involving crystallization solvent molecules. Compound 2 is dimetallic, and both nickel centers show an octahedral coordination environment, whereas complexes 3 and 5 display a typical carboxylate-bridged paddlewheel-type structure with two metal atoms connected by four bridging carboxylate ligands. All compounds show weak antiferromagnetic interactions except 3 , where a strong intra-dimer antiferromagnetic coupling is observed. Compound 4 also shows a strong zero field splitting. [ABSTRACT FROM AUTHOR]

Five nickel complexes, [Ni2(3,4,5-tmb)4(4,4′-bpy)] ( 1), [Ni2(2-ntc)4(4,4′-bpy)] ( 2), [Ni(9-atc)2(4,4′-bpy)] ( 3), [Ni(3,4,5-tmb)2( t-bpee)] ( 4), and [Ni2(2-ntc)4( t-bpee)2] ( 5) (3,4,5-tmb=3,4,5-trimethoxybenzoate; 2-ntc=2-naphthalenecarboxylate; 9-atc=9-anthracenecarboxylate; 4,4′-bpy=4,4′-bipyridine; t-bpee= trans-1,2-bis(4-pyridyl)ethylene), are prepared. They are characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, and single-crystal and powder X-ray diffraction. 1 and 2 form linear chains of paddlewheel units joined by 4,4′-bpy ligands; 3 and 4 display zigzag chains formed by cis-bis(chelate) Ni(O2CR)2 units joined by 4,4′-bpy and t-bpee, respectively; and the structure of 5 consists of double chains. The magnetic behavior of the compounds is also studied, and DFT calculations using the broken-symmetry approximation are performed to gain a better understanding of the strong antiferromagnetism found in 1. [ABSTRACT FROM AUTHOR]

A series of 2-D nickel compounds with the stoichiometry [NiCl2(N--N)] has been prepared, [N--N = pyrazine (1), 4,4'-bipyridine (2), fratts-4,4'-azopyridine (3), trans-1,2-bis(4-pyridyl)ethylene (4), and l,2-bis(4-pyridyl)ethane (5)]. The complex [NiBr2(4,4'-bpy)] (6) was also obtained for comparative reasons. Compound 2 is the f} phase of the previously reported complex [NiCl2(4,4'-bpy)]. The syntheses of complexes 1--6 were carried out using solvothermal and microwave techniques. The compounds have been characterized by elemental analysis, infrared spectroscopy, thermogravimetry, and powder X-ray diffraction. The crystal structures of compounds 1, 4, and 5 have been solved using ab initio X-ray powder diffraction methods. Compounds 1--6 show the same arrangement, and their structures are described as layers formed by [NiX2] chains linked perpendicularly by N--N ligands. The magnetic properties of the compounds are explained as a balance between the ferromagnetic interactions along the [NiXj chains and the antiferromagnetic interactions between chains from different layers. This work demonstrates that this balance can be tuned by the length of the N--N ligand. [ABSTRACT FROM AUTHOR]

Several metal-organic frameworks of nickel(II) were obtained starting from the molecular complex 1, [Ni(OH2)4(4-pyc)2] (4-pyc = 4-pyridinecarboxylate or isonicotinate). By using different reaction conditions, two polymorphs of the anhydrous complex [Ni(4-pyc)2] n ( 2a and 2b) and the polynuclear compound [Ni5(OH2)3(4-pyc)10] n ( 3) were obtained in very high yield. All of the compounds were characterized by elemental analysis and spectroscopic data. The crystal structure determination of compounds 2b and 3 was also carried out. Structural and topological analysis of these new structural types and other related ones were performed. It was found that compounds 2a and 2b are a rare case of coordination framework isomers. Thermogravimetric studies indicate that compounds 2b and 3 lose the pore-allocated solvent molecules at moderate temperatures without any significant structural change, and at higher temperatures, compounds 1 and 3 are transformed into 2a. Textural parameters that characterize the microporous networks for 2b and 3 were obtained by nitrogen-adsorption measurements. For both samples, the micropore size distribution indicates cylindrical pores with diameters of 0.85 ( 2b) and 0.90 nm ( 3). The values of Brunauer-Emmett-Teller and Langmuir surface areas are 178 and 185 m2 g-1 for compound 2b, and 995 and 982 m2 g-1 for compound 3. Micropore volumes are 0.065 and 0.350 cm3 g-1 for 2b and 3, respectively. The magnetic properties of compounds 1, 2a, and 2b are consistent with the presence of zero-field splitting and a small antiferromagnetic coupling between the metal atoms. The magnetic properties of the pentanuclear compound 3 were analyzed by considering one monomer with zero-field splitting caused by axially distorted NiII octahedral compounds, and two dimeric fragments with magnetic interactions within each dimetallic unit. [ABSTRACT FROM AUTHOR]

• Amidinato Ru 2 compounds with a large variety of oxidation states can be prepared. • The E of the π* and δ* levels can be finely tuned by changing the amidinates ligands. • Magnetic, structural and spectroscopic data are carefully analyzed in this work. • Potential use in electronic devices and bioinorganic applications are considered. The amidinate anions have been widely used in the formation of dinuclear complexes with paddlewheel structure. The higher donor character of this type of ligands, compared to carboxylate ligands, increases the electronic density of the dimetallic units giving, in the case of ruthenium, stable complexes with a large variety of oxidation states containing Ru 2 4+, Ru 2 5+ and Ru 2 6+ units. Even complexes with Ru 2 2+, Ru 2 3+ and Ru 2 7+ cores have been detected in electrochemical measurements and isolated in some cases. The influence of formamidinate and benzamidinate ligands in the synthesis, characterization, properties and reactivity of metal-metal bonded diruthenium complexes with paddlewheel structure in several oxidation states is considered. A revision of the electronic and magnetic properties of diruthenium complexes and their relationship with the different electronic configurations found in this type of complexes is broadly documented. Additionally, the switching between oxidation states is considered through the discussion of the results obtained by electrochemical measurements. Finally, the most relevant applications of the amidinatodiruthenium complexes are also reviewed. [ABSTRACT FROM AUTHOR]