Compounds Of Ru Research Articles

Thermodynamic and transport properties of Ru2−x Fe x CrSi (1.3 ≤ x ≤ 1.8)

We have measured the temperature (T) dependences of the electric resistivity, ρ(T), and the specific heat, Cp(T), of the ferromagnetic full-Heusler compound Ru2−xFexCrSi (1.3 ≤ x ≤ 1.8). ρ(T) shows a metallic behavior (∂ρ/∂T > 0) for 20 ≲ T ≤ 300 K and nominal upturn at around 20 K for all samples. In the low-temperature range, Cp(T) can be described by Debye’s T3 law. Although the coefficient of the lattice part of Cp(T), β, is insensitive for the Fe concentration x, the electronic specific heat part, γ, decreases with increasing x. The values of the total densities of states (Dtotal(EF)) estimated from γ were 12.8, 10.1, and 9.6 states/f.u. eV for x = 1.3, 1.6, and 1.8, respectively. The values of majority spin band (D↑(EF)) and the minority spin band (D↓(EF)) were also estimated using γ and the spin polarization P defined by Andreev-reflection experiments.

Spin-glass and antiferromagnetic transitions in Ru2−xFexCrSi

In this study the properties of the Heusler compounds Ru2−xFexCrSi (0< x < 0.1) are investigated. Ru1.9Fe0.1CrSi was revealed to exhibit two anomalies in the temperature dependence of magnetization M(T); one is a peak in M(T) at T*N ∼ 30 K and the other is strong irreversibility in M(T) below T*N, the onset of which is defined as Tg. M(T) and specific heat CP(T) of Ru2CrSi are measured. A clear peak is observed in both M(T) and CP(T). This is in quite contrast to the case for Ru1.9Fe0.1CrSi, where no anomaly in CP(T) was observed at T*N or at any other temperatures. These indicate that an antiferromagnetic transition occurs at TN = 14 K in Ru2CrSi. For x = 0.02 the characteristic two anomalies in M(T) are also found at various magnetic fields, and their field dependence is basically the same as that for x = 0.1. These two anomalies are suggestive of successive spin-glass transitions. As for the dependence of the two anomalies on x, Tg does not change with x, whereas T*N decreases with decreasing x and seems to approach Tg at zero field.

New diruthenium (II,III) compounds bearing terminal olefin groups

The reaction between Ru2(DmAniF)3(OAc)Cl (DmAniF is N,N′-di(m-methoxyphenyl)formamidinate) and HO2C(CH2)mCHCH2 (m=3, 4 and 8) under reflux afforded new diruthenium species Ru2(DmAniF)3(O2C(CH2)mCHCH2)Cl (m=3, 1a; 4, 1b; and 8, 1c). Similarly, the reaction between cis-Ru2(DmAniF)2(OAc)2Cl and HO2C(CH2)mCHCH2 resulted in Ru2(DmAniF)2(O2C(CH2)mCHCH2)2Cl (m=3, 2a; and 8, 2c). Compounds 2 subsequently underwent an olefin ring closing metathesis reaction catalyzed by (Cy3P)2Cl2Ru(CHPh) to afford the dimerized compounds Ru2(DmAniF)2(μ-O2C(CH2)mCH)2Cl (m=3, 3a; and 8, 3c). All compounds reported herein were analyzed by voltammetry, high resolution mass spectrometry and Vis–NIR spectroscopy, with the structures of 1c and 2c established through X-ray single crystal diffraction.

SPINEL COMPOSITION, PGE GEOCHEMISTRY AND MINERALOGY OF THE CHROMITITES FROM THE VOURINOS OPHIOLITE COMPLEX, NORTHWESTERN GREECE

The Vourinos ophiolite complex, in northwestern Greece, hosts abundant deposits of chromian spinel of historical economic importance. The chromitites have been investigated with regards to the composition of the chromian spinel and olivine, and the distribution of the platinum-group elements (PGE) minerals. Chromitites are composed of magnesiochromite, accompanied by magnesian olivine and locally abundant micro-inclusions of pargasitic amphibole. The composition of magnesiochromite varies significantly in southern Vourinos (Cr#: 0.58–0.81), and less in northern Vourinos (Cr#: 0.75–0.83). Olivine cores from the chromite deposits of southern Vourinos have lower Mg# and Ni than those of northern Vourinos. The PGE contents vary between 13.6 and 375.4 ppb, and are higher in IPGE with respect to PPGE, which is typical of mantle-hosted ophiolitic chromitites. The PGE abundances of southern Vourinos chromitites correlate positively with the Cr# of the ore-hosted magnesiochromite. Consistent with the geochemical data, the platinum-group mineral (PGM) assemblage is almost exclusively dominated by Ru–Os–Ir phases. Two distinct PGM assemblages have been recognized: 1) a primary one, formed at the early magmatic stage before or during magnesiochromite crystallization, and 2) a secondary one, formed by desulfurization–oxidation of primary PGM sulfide precursors (laurite). This laurite has a Ru# value ranging from 0.55 to 0.98. The secondary assemblage is dominated by oxygen-bearing compounds of Ru–Os–Ir–Fe–Ni, some of which exhibit intriguing internal rosette-like textures. Raman spectroscopy data on these PGE-bearing oxygen compounds did not reveal any OH − content, indicating that they might represent oxides. Compositional discrepancies regarding the NiO content and the Mg# of olivine, as well as the Os content of laurite, suggest that the chromian spinel deposits from the south and the north of the complex have been formed under different physicochemical [ f ( S 2 )–T] conditions. Combined geological, mineralogical and compositional data indicate that the Vourinos chromitites crystallized from a progressively differentiating melt of boninitic affinity.

Transport Properties of Heusler Compound Ru2−xFexCrSi under Pressure

We investigated transport properties of the full-Heusler compound Ru2−xFexCrSi (x = 0.1), which is an insulator, under pressure P up to 8 GPa. The temperature dependence of electric resistance R(T) for Ru1.9Fe0.1CrSi is insensitive to pressure. R(T) is not described by the simple activation-type but -logT in the wide T and all P range we measured. This might be due to atomic disorder in the crystalline.

Magnetic Properties of Ru-rich Ru2−x Fe x CrZ (Z=Si, Ge)

The properties of Heusler compounds Ru2−xFexCrGe are investigated and compared with those of Ru1.9Fe0.1CrSi. Ru2CrGe is confirmed to exhibit an antiferromagnetic transition with Neel temperature 13 K by magnetic susceptibility and specific heat measurements. When Fe is substituted for Ru, a peak in the magnetic susceptibility is observed, and in the lower temperature region irreversibility between temperature dependences of magnetization for zero-field-cooling and field-cooling conditions is found. Nevertheless, in specific heat of Ru1.9Fe0.1CrGe, there is no anomaly to indicate phase transition. The specific heat is almost identical to that for Ru1.9Fe0.1CrSi. The above results demonstrate that the magnetic states in the low temperature region of Fe-substituted samples are spin-glass-like states. Slight substitution of Fe for Ru destroys the long-range-order and lead to peculiar spin-glass-like states.

PLATINUM-GROUP MINERALS FROM THE OLKHOVAYA-1 PLACERS RELATED TO THE KARAGINSKY OPHIOLITE COMPLEX, KAMCHATSKIY MYS PENINSULA, RUSSIA

Mineral assemblages from the Olkhovaya–1 River placers, in Kamchatka, Far-Eastern Russia, provide genetic information on their evolution. The minerals are dominated by Os–Ir–Ru alloys (80%), consisting of all possible mineral species, and Pt–Fe alloys consisting of native platinum, Fe-rich platinum and isoferroplatinum. The following features of the mineral assemblage are characteristic of mineralization associated with an ophiolitic complex: (1) in the Os–Ru–Ir diagram, the compositions of the hexagonal alloy form a ruthenium trend; (2) there are two typical equilibrium magmatic parageneses of alloys: early osmium– iridium, and later isoferroplatinum–ruthenium, which both are associated with laurite and the solid solution laurite–irarsite (Ru,Ir) (S,As) 2 . The cooperite, sperrylite and Pd minerals formed at the postmagmatic stage. Tetraferroplatinum–tulameenite, replacing the Pt–Fe alloys, as well as the multicomponent compounds of Ru, Os, Ir, Rh, Pt with Fe replacing the Os–Ir–Ru alloys and PGE sulfides, result from serpentinization of PGM-bearing rocks. The PGM assemblage in the Ol’khovaya–1 River placers is related to the Karaginsky ophiolite complex of the Kamchatskiy Mys Peninsula.

Diruthenium−Tin Complexes from the Reaction of Ph2SnH2 with Ru(CO)5 and Their Reactions with Bis(tri-tert-butylphosphine)platinum

Ph2SnH2 reacts with 2 equiv of Ru(CO)5 to give the compound [Ru(CO)4H]2(μ-SnPh2) (1) in 57% yield by loss of CO from each molecule of Ru(CO)5 and by an oxidative addition of an Sn−H bond to each ruthenium atom. When compound 1 was irradiated with visible radiation, the compound Ru2(CO)8(μ-SnPh2) (2) was obtained by loss of hydrogen. A mechanism involving loss of CO followed by loss of H2 and readdition of CO is supported by isotopic labeling studies. Compound 1 reacts with Pt(PBut3)2 to yield the new trimetallic compound Ru2(CO)7(μ-SnPh2)(μ-H)2(μ-PtPBut3) (3). Compound 3 contains a Pt(CO)(PBut3) group bridging the Ru−Ru bond and two bridging hydrido ligands. Compound 2 reacts with Pt(PBut3)2 to yield the two products PtRu2(CO)8)(PBut3)(μ-SnPh2) (4; 78% yield) and Pt2Ru2(CO)8(PBut3)2(μ-SnPh2) (5; 15% yield) by the addition of one and two Pt(PBut3) groups to the metal−metal bonds of 2. The first Pt(PBut3) addition occurs at the Ru−Ru bond to form 4. The second Pt(PBut3) addition occurs at one of the Ru−Sn b...

Mixed-Valent Metals Bridged by a Radical Ligand: Fact or Fiction Based on Structure-Oxidation State Correlations

Electron-rich Ru(acac)2 (acac- = 2,4-pentanedionato) binds to the pi electron-deficient bis-chelate ligands L, L = 2,2'-azobispyridine (abpy) or azobis(5-chloropyrimidine) (abcp), with considerable transfer of negative charge. The compounds studied, (abpy)Ru(acac)2 (1), meso-(mu-abpy)[Ru(acac)2]2 (2), rac-(mu-abpy)[Ru(acac)2]2 (3), and (mu-abcp)[Ru(acac)2]2 (4), were calculated by DFT to assess the degree of this metal-to-ligand electron shift. The calculated and experimental structures of 2 and 3 both yield about 1.35 A for the length of the central N-N bond which suggests a monoanion character of the bridging ligand. The NBO analysis confirms this interpretation, and TD-DFT calculations reproduce the observed intense long-wavelength absorptions. While mononuclear 1 is calculated with a lower net ruthenium-to-abpy charge shift as illustrated by the computed 1.30 A for d(N-N), compound 4 with the stronger pi accepting abcp bridge is calculated with a slightly lengthened N-N distance relative to that of 2. The formulation of the dinuclear systems with monoanionic bridging ligands implies an obviously valence-averaged Ru(III)Ru(II) mixed-valent state for the neutral molecules. Mixed valency in conjunction with an anion radical bridging ligand had been discussed before in the discussion of MLCT excited states of symmetrically dinuclear coordination compounds. Whereas 1 still exhibits a conventional electrochemical and spectroelectrochemical behavior with metal centered oxidation and two ligand-based one-electron reduction waves, the two one-electron oxidation and two one-electron reduction processes for each of the dinuclear compounds Ru2.5(L*-)Ru2.5 reveal more unusual features via EPR and UV-vis-NIR spectroelectrochemistry. In spite of intense near-infrared absorptions, the EPR results show that the first reduction leads to Ru(II)(L*-)Ru(II) species, with an increased metal contribution for system 4*-. The second reduction to Ru(II)(L2-)Ru(II) causes the disappearance of the NIR band. One-electron oxidation of the Ru2.5(L*-)Ru2.5 species produces a metal-centered spin for which the alternatives RuIII(L0)Ru(II) or Ru(III)(L*-)Ru(III) can be formulated. The absence of NIR bands as common for mixed-valent species with intervalence charge transfer (IVCT) absorption favors the second alternative. The second one-electron oxidation is likely to produce a dication with Ru(III)(L0)Ru(III) formulation. The usefulness and limitations of the increasingly popular structure/oxidation state correlations for complexes with noninnocent ligands is being discussed.

Synthesis, Separation, and Circularly Polarized Luminescence Studies of Enantiomers of Iridium(III) Luminophores

A family of heteroleptic (C;N)2Ir(acac) and homoleptic fac-Ir(C;N)3 complexes have been synthesized and their photophysical properties studied (where C;N = a substituted 2-phenylpyridine and acac = acetylacetonate). The neutral Delta and Lambda complexes were separated with greater than 95% enantiomeric purity by chiral supercritical fluid chromatography, and the solution circular dichroism and circularly polarized luminescence spectra for each of the enantio-enriched iridium complexes were obtained. The experimentally measured emission dissymmetries (gem) for this series compared well with predicted values provided by time-dependent density functional theory calculations. The discovered trend further showed a correlation with the dissymmetries of ionic, enantiopure hemicage compounds of Ru(II) and Zn(II), thus demonstrating the applicability of the model for predicting emission dissymmetry values across a wide range of complexes.

Ruthenium Carbonyl Cluster Complexes with Phenylgermyl Ligands from the Reactions of Ph3GeH with Ru(CO)5 and Ru3(CO)12

Four new triphenylgermylruthenium carbonyl compounds HRu(CO)4GePh3, 14; Ru(CO)4(GePh3)2, 15; Ru2(CO)8(GePh3)2, 16; and Ru3(CO)9(GePh3)3(μ-H)3, 17 were obtained from the reaction of Ru(CO)5 with Ph3GeH in hexane solvent at reflux, 68 °C. The major product 14 was formed by loss of CO from the Ru(CO)5 and an oxidative addition of the GeH bond of the Ph3GeH to the metal atom. This six coordinate complex contains one terminal hydrido ligand. Compound 15 is formed from 14 and contains two trans-positioned GePh3 ligands in the six coordinate complex. Compound 16 contains two Ru(CO)4(GePh3) fragments joined by an Ru–Ru single bond. Compound 17 contains a triangular cluster of three ruthenium atoms with three bridging hydrido ligands and one terminal GePh3 ligand on each metal atom. When heated to 125 °C, 14 was converted to the new triruthenium compound Ru3(CO)10(μ-GePh2)2, 18. Compound 18 consists of a triangular tri-ruthenium cluster with two GePh2 ligands bridging two different edges of the cluster and one bridging CO ligand. Ru3(CO)12 was found to react with Ph3GeH at 97 °C to yield three products: 15, and two new compounds Ru3(CO)9(μ-GePh2)3, 19 and Ru2(CO)6(μ-GePh2)2(GePh3)2, 20 were obtained. Compound 19 is similar to 18 having a triangular tri-ruthenium cluster but has three bridging GePh2 ligands, one on each Ru–Ru bond. Compound 20 contains only two ruthenium atoms joined by a single Ru–Ru bond that has two bridging GePh2 ligands and a terminal GePh3 ligand on each metal atom. All compounds were characterized by a combination of IR, 1H NMR, single-crystal X-ray diffraction analyses.

Photochemically promoted regiospecific P–C bond cleavage in the diruthenium compound Ru2(CO)2(bmf): X-ray diffraction structure of Ru2(CO)6[μ-C=C(PPh2)C(O)OCH(OMe)](μ-PPh2)

The ruthenium cluster Ru3(CO)12 reacts with the diphosphine ligand 3,4-bis(diphenylphosphino)-5-methoxy-2(5H)-furanone (bmf) in refluxing toluene to furnish the donor–acceptor compound Ru2(CO)2(bmf) as a 1 : 1 mixture of diastereomers. Photolysis of Ru2(CO)2(bmf) using 366 nm light leads to the oxidative cleavage of a P–C bond and formation of the phosphido-bridged complex Ru2(CO)6[μ-C=C(PPh2)C(O)OCH(OMe)](μ-PPh2). The regioselective Ph2P–C(furanone ring) bond activation attendant upon optical excitation is traced to the phosphine group that was β to the furanone carbonyl group, as established by X-ray analysis of one of the diastereomers of Ru2(CO)6[μ-C=C(PPh2)C(O)OCH(OMe)](μ-PPh2). Both diruthenium products have been fully characterized in solution by IR and NMR (1H and 31P) spectroscopies and elemental analyses. The observed regioselectivity associated with the P–C bond activation in Ru2(CO)2(bmf) is discussed with respect to the chemistry of other bmf-substituted compounds prepared by our groups.

Diphosphine ligand substitution in H4Ru4(CO)12: X-ray diffraction structures and reactivity studies of the cluster compounds H4Ru4(CO)10(P–P) [where P–P–(Z)–Ph2PCH–CHPPh2, bpcd

The tetraruthenium cluster H4Ru4(CO)12 (1) has been studied for its reactivity with the unsaturated diphosphine ligands (Z)–Ph2PCH–CHPPh2 and 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) under thermal, near-UV photolysis, and Me3NO-assisted activation. All three cluster activation methods promote loss of CO and furnish the anticipated substitution products H4Ru4(CO)10[(Z)–Ph2PCH–CHPPh2] (2) and H4Ru4(CO)10(bpcd) (3) that possess a chelating diphosphine ligand. Clusters 2 and 3 have been characterized in solution by IR and NMR spectroscopies, and these data are discussed with respect to the crystallographically determined structure for both new cluster compounds. The 31P NMR spectral data and the solid-state structures confirm the presence of a chelating diphosphine ligand in clusters 2 and 3. Cluster 2 crystallizes in the monoclinic space P21/c, a=11.768(6) A, b=18.521(9) A, c=20.48(1) A, β=102.291(8)°, V=4361(4) A3, Z=4, and d calc=1.726 Mg/m3; R=0.0225, R w=0.0491 for 6798 reflections with I > 2σ(I). The four bridging hydrides were located in H4Ru4(CO)10[(Z)–Ph2PCH–CHPPh2] and their adopted positions are discussed relative to the solution 1H NMR spectrum. H4Ru4(CO)10(bpcd) crystallizes in the orthorhombic space Pbca, a=19.072(3) A, b=20.169(3) A, c=22.774(3) A, V=8760(2) A3, Z=8, and d calc=1.870 Mg/m3; R=0.0428, R w=0.0896 for 10296 reflections with I > 2σ(I). Sealed NMR tubes containing clusters 2 and 3 were found to be exceeding stable towards near-UV light and temperatures up to ca. 125 °C. The surprisingly robust behavior of 2 and 3 is contrasted with the related cluster Ru3(CO)10(bpcd) that undergoes fragmentation to the donor-acceptor compound Ru2(CO)6(bpcd) and the phosphido-bridged compound Ru2(CO)6(μ–PPh2)[μ–C–C(PPh2)C(O)CH2C(O)] under mild conditions. The electrochemical properties of each substituted cluster have been investigated by cyclic voltammetry, and our findings are discussed with respect to the reported electrochemical data on the parent cluster H4Ru4(CO)12.

Preparation and Characterization of a Family of Ru2 Compounds Bearing Iodo/Ethynyl Substituents on the Periphery

A high-yield synthesis of mixed-bridging-ligand Ru2 compounds, Ru2(D(3,5-Cl2Ph)F)(4-n)(OAc)nCl [n = 1 (1) and 2 (2)] was developed, where D(3,5-Cl2Ph)F is bis(3,5-dichlorophenyl)formamidinate. The acetate ligands in 1 and 2 can be quantitatively displaced with DMBA-I to yield Ru2(D(3,5-Cl2Ph)F)3(DMBA-I)Cl (3) and Ru2(D(3,5-Cl2Ph)F)2(DMBA-I)2Cl (4), respectively, where DMBA-I is N,N'-dimethyl-4-iodobenzamidinate. When compound 2 was treated with 1 equiv of HDMBA-I, a unique Ru2 compound containing three different types of bidentate bridging ligands, cis-Ru2(D(3,5-Cl2Ph)F)2(DMBA-I)(OAc)Cl (5), was obtained. Subsequent reactions between 3/4 and (trimethylsilyl)acetylene under Sonogashira coupling conditions resulted in Ru2(D(3,5-Cl2Ph)F)(4-n)(DMBA-C[triple bond]CSiMe3)nCl [n = 1 (6) and 2 (8)] in excellent yields, which were converted to the corresponding bis(phenylacetylide) compounds Ru2(D(3,5-Cl2Ph)F)(4-n)(DMBA-C[triple bond]CSiMe3)n(C[triple bond]CPh)2 [n = 1 (7) and 2 (9)]. Structural studies of several compounds provided insights about the change in Ru2 coordination geometry upon the displacement of bridging and axial ligands. Voltammetric studies of these compounds revealed rich redox characteristics in all Ru2 compounds reported and a minimal electronic perturbation upon the peripheral Sonogashira modification.

Pentamethylcyclopentadienyl Ruthenium(III) vs. Hexamethylbenzene Ruthenium(II) in Sulfur‐Centered Reactivity of Their Thioether‐Thiolate and Allied Complexes

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Pentamethylcyclopentadienyl Ruthenium(III) vs Hexamethylbenzene Ruthenium(II) in Sulfur-Centered Reactivity of Their Thioether-Thiolate and Allied Complexes

The reactivity features of [Cp*Ru(III){eta(3)-tpdt)}] (7) and [(HMB)Ru(II)(eta(3)-tpdt)] (10) {Cp* = eta(5)-C(5)Me(5); HMB = eta(6)-C(6)Me(6); tpdt = 3-thiapentane-1,5-dithiolate, S(CH(2)CH(2)S(-))(2)} are presented, together with selected aspects of their (eta(3)-apdt) analogues 8 and 11 {apdt = 3-azapentane-1,5-dithiolate, HN(CH(2)CH(2)S(-))(2)}. This account will highlight the differences observed in their reactions with metal fragments of compounds of Ru and groups 10 and 11 in various coordination environments and with alkylating agents, including alpha,omega-dibromoalkanes. The mechanistic pathway of the alkylation of 7 will be discussed in some detail.

Synthetic, structural and antifungal studies of coordination compounds of Ru(III), Rh(III) and Ir(III) with tetradentate schiff bases

A series of octahedral Ru(III), Rh(III) and Ir(III) complexes have been prepared with tetradentate Schiff bases derived by condensing isatin with 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane, 1,2-diaminobenzene and 1,3-diaminobenzene. The obtained complexes were characterized on the basis of their elemental analyses, magnetic moment, conductance, IR electronic, 1HNMR and FAB mass spectra, as well as thermal analyses. The Ru(III) complexes are low spin paramagnetic, while Rh(III) and Ir(III) behave as diamagnetic complexes. The IR spectral data revealed that all the Schiff bases behave as tetradentate and are coordinated to Ru(III), Rh(III) and Ir(III) via nitrogen and oxygen. Antifungal studies of the ligands as well as their complexes were carried out by the agar plate method.

Iterative Synthesis of Oligoynes Capped by a Ru2(ap)4-terminus and Their Electrochemical and Optoelectronic Properties

Cross-coupling reactions between terminal ethynes (HC⋮CY) and Ru2(ap)4(C2(k-1)H) under Hay conditions, where ap is 2-anilinopyridinate and k = 2−5, resulted in compounds Ru2(ap)4(C2kY) (Y = SiiPr3 and Ph) along with the homocoupling products YC4Y and [Ru2(ap)4]2(μ-C4(k-1)). Compounds Ru2(ap)4(C2kY) display two reversible Ru2-based one-electron couples: an oxidation and a reduction. The HOMO−LUMO gaps (Eg) estimated from electrode potentials correlate linearly with the number of acetylenic bonds (k) within each series. Both nonlinear absorption and degenerate four-wave mixing measurements were carried out at both 532 and 800 nm with nano- and femtosecond laser pulses.

Selective Ligand Modification on the Periphery of Diruthenium Compounds: Toward New Metal-Alkynyl Scaffolds

Diruthenium compounds Ru2(DmAniF)3(OAc)Cl (1, DmAniF is N,N‘-di(m-methoxyphenyl)formamidinate) and cis-Ru2(DmAniF)2(OAc)2Cl (6) reacted with N,N‘-dimethyl-4-iodobenzamidine (HDMBA-I) to furnish new compounds Ru2(DmAniF)3(DMBA-I)Cl (2) and cis-Ru2(DmAniF)2(DMBA-I)2Cl (7), respectively. Both compounds 2 and 7 were modified with a terminal alkyne under Sonogashira conditions. Examples reported include 2 cross-coupled with HC⋮CSiiPr3 or HC⋮CFc to yield Ru2(DmAniF)3(DMBA-4-C2SiiPr3)Cl (3a) or Ru2(DmAniF)3(DMBA-4-C2Fc)Cl (3b), respectively, and 7 cross-coupled with HC⋮CFc to yield cis-Ru2(DmAniF)2(DMBA-4-C2Fc)2Cl (8). The peripherally modified compounds (2, 3a/3b, 7, and 8) were further alkynylated at the axial positions of the Ru2 core to yield a series of bis-alkynyl adducts: Ru2(DmAniF)3(DMBA-4-C2SiiPr3)(C4SiMe3)2 (4a), Ru2(DmAniF)3(DMBA-4-C2Fc)(C4SiMe3)2 (4b), Ru2(DmAniF)3(DMBA-I)(C4SiMe3)2 (5), cis-Ru2(DmAniF)2(DMBA-4-C2Fc)2(C2Ph)2 (9), and cis-Ru2(DmAniF)2(DMBA-I)2(C2Ph)2 (10). All compounds reported were characterized with voltammetric, vis−NIR, and NMR (whenever applicable) techniques. Molecular structures of compounds 1, 4a, 5, 6, 9, and 10 were established through X-ray diffraction studies.

Paramagnetic Precursors for Supramolecular Assemblies: Selective Syntheses, Crystal Structures, and Electrochemical and Magnetic Properties of Ru2(O2CMe)4-n(formamidinate)nCl Complexes, n = 1−4

Reactions of Ru(2)(O(2)CMe)(4)Cl with two formamidines, HDXyl(2,6)F = N,N'-di(2,6-xylyl)formamidine and HDAniF = N,N'-di(p-anisyl)formamidine, have been investigated with the idea of synthesizing compounds with a mixed set of ligands having different labilities to be used as precursors of paramagnetic, higher-order assemblies. Depending on the formamidine and the reaction conditions, several Ru(2)(5+) compounds of the type Ru(2)(O(2)CMe)(4)(-)(n)(DArF)(n)Cl (DArF = anion of an N,N'-diarylformamidine) have been isolated. With the bulky formamidine HXyl(2,6)F, the compounds Ru(2)(O(2)CMe)(3)(DXyl(2,6)F)Cl (1) and trans-Ru(2)(O(2)CMe)(2)(DXyl(2,6)F)(2)Cl (2) were obtained. From reactions with appropriate amounts of HDAniF in THF and in the presence of NEt(3) and LiCl, complexes of the general type Ru(2)(O(2)CMe)(4)(-)(n)(DArF)(n)Cl (n = 1-4) were selectively obtained. For n = 2, only the cis isomer was obtained. The choice of solvent in reactions of Ru(2)(O(2)CMe)(4)Cl and HDAniF is of great importance. Toluene favored the formation of the fully substituted Ru(2)(5+) complex Ru(2)(DAniF)(4)Cl (3), whereas MeOH resulted in a disproportionation reaction that gave the edge-sharing bioctahedral Ru(3+)Ru(3+) complex [trans-Ru(2)(mu-OMe)(2)(mu-O(2)CMe)(2)(HDAniF)(4)]Cl(2) (6) and the Ru(2)(4+) complex Ru(2)(DAniF)(4) (7). Complexes 6 and 7 with an Ru(2)(6+) and Ru(2)(4+) core, respectively, are diamagnetic, whereas all Ru(2)(5+) complexes are paramagnetic with sigma(2)pi(4)delta(2)(pi*delta*)(3) ground-state electronic configurations and large zero-field splitting contributions. All compounds show rich and complex electrochemical behavior.