Pentamethylcyclopentadienyl Ruthenium Complexes with Sulfur- and Selenium-Donor Ligands

Exploring the persistence of the fluorinated thiolate 2,3,5,6-S(C6F4H-4) motif to establish πF-πF stacking in metal complexes: a crystal engineering perspective

π-π stacking interactions are versatile because they are involved in many processes, such as protein folding, DNA stacking, and drug recognition. However, from the point of view of crystal engineering, there is an incipient knowledge of its exploitation. A comparison of these interactions with hydrogen bonds shows a huge difference in their employment as a reliable non-covalent interaction. And different reasons can be listed to explain why hydrogen bonding can be considered a more robust interaction than π-π stacking. For instance, hydrogen bonds encompass a wide energy range (25-40 kJ mol-1). From this, these interactions can be classified as strong, moderate, and weak. Hence, the first two can be considered highly to moderately directional to be exploited in crystal engineering. This aspect is relevant for them to be used in a relatively reliably way in this area of supramolecular chemistry. On the other hand, in the case of π-π stacking, the energy range is 0-10 kJ mol-1, thus implying that hydrogen bonds or any other energetically more robust contact would predominate in the competition for establishing packing interactions in a given arrangement. In this sense, if stacking is pretended to be exploited from the point of view of crystal engineering, one of the points that must be ensured is that this interaction will be the one energetically predominant. However, although there are other factors to consider, it seems that energetics is the dominant one. In this line, our research group has obtained and studied many single-crystalline structures of coordination and organometallic compounds containing fluorinated thiolates. This being particularly true in the case of the thiolate 2,3,5,6-S(C6F4H-4) bound to different metals, where it has been observed that they preferentially tend to establish πF-πF stacking interactions, results that have been reported in several papers. Thus, from this perspective, we have explored, using ConQuest (CCDC) a number of structures to observe how feasible is to find stacking in coordination and organometallic compounds containing the thiolate 2,3,5,6-S(C6F4H-4).

Carboxamide carbonyl-ruthenium(ii) complexes: detailed structural and mechanistic studies in the transfer hydrogenation of ketones

The organo-carboxamide carbonyl-ruthenium(ii) complexes displayed moderate catalytic activities in the transfer hydrogenation of a broad spectrum of ketones.

4-Coordinated, 14-electron ruthenium(ii) chalcogenolate complexes: synthesis, electronic structure and reactions with PhICl2 and organic azides

The 4-coordinated Ru^II chalcogenolate complexes [Ru(STipp)₂(PPh₃)₂] (Tipp = 2,4,6-triisopropylphenyl, 1) and [Ru(SeMes)₂(PPh₃)₂] (Mes = 2,4,6-trimethylphenyl, 2) have been synthesized, and their reactions with PhICl₂ and organic azides have been studied. Complex 2 synthesized from [Ru^II(PPh₃)₃Cl₂] and NaSeMes displays a seesaw structure with P-Ru-P and Se-Ru-Se bond angles of 103.43(13) and 145.26(6)°, respectively. Natural bond order analyses revealed that in each of 1 and 2, there are two n →σ* (donor-acceptor) π interactions between the chalcogen lone pairs and the Ru-P antibonding molecular orbitals. The calculated second-order perturbation interaction energies of the two interactions for 1 (20.5 and 18.3 kcal mol^-1) are stronger than those of 2 (13.6 and 11.0 kcal mol^-1), suggesting the thiolate ligand (TippS^-) is a stronger π-donor than the selenolate ligand (MesSe^-) with respect to Ru^II. Chlorination of 1 with PhICl₂ afforded the dichloride complex [Ru(STipp)₂Cl₂(PPh₃)] (3), which was hydrolyzed to the hydroxo complex [Ru(STipp)₂(OH)Cl(PPh₃)] (4) after column chromatography on silica in air. Treatment of 4 with HCl and methyl triflate gave 3 and [Ru(STipp)₂(OH)(OTf)(PPh₃)] (OTf = triflate, 5), respectively. Reactions of 1 and 2 with p-tolyl azide (p-tolN₃) afforded the tetrazene complexes [Ru{N₄(p-tol)₂}(ER)₂(PPh₃)] (ER = STipp (6), SeMes (7)), whereas that with tosyl azide (TsN₃) gave the imido complexes [Ru(κ²-NTs)(STipp)₂(PPh₃)] (ER = STipp (8), SeMes (10)). The short Ru-N_imido distances in 8 [1.883(3) Å] and 10 [1.892(2) Å] are indicative of multiple bond character. Treatment of 8 with TsN₃ afforded the tetrazene complex [Ru(N₄Ts₂)(STipp)₂(PPh₃)] (9), but no cycloaddition was found between 10 and TsN₃. Nucleophilic attack of the imido ligand in 10 with methyl triflate yielded the amido complex [Ru(κ²-NMeTs)(SeMes)₂(PPh₃)](OTf) (11). The crystal structures of 2, 4, 6, and 8-11 have been determined.

Synthetic and X-ray Structural and Reactivity Studies of Cp*RuIV Complexes Containing Bidentate Dithiocarbonate, Xanthate, Carbonate, and Phosphinate Ligands (Cp* = η5-C5Me5)

The reaction of [Cp*RuCl2]2 (1; Cp* = eta5-C5Me5) with tetraalkyldithiuram disulfides (R2NC(S)SS(S)CNR2, R = Me, Et), isopropylxanthic disulfide ([iPrOC(S)S]2), and bis(thiophosphoryl) disulfide ([(iPrO)2P(S)S]2) led to the isolation of dark-red crystalline solids of Cp*RuIVCl2(eta2-dithiolate) complexes [dithiolate = S2CNR2, DTCR (2a, R = Me; 2b, R = Et), S2COiPr (3), and S2P(iPrO)2 (4)]. Dichlorido substitution in 2 and 3 with DTCEt and S2COiPr anions yielded RuIV derivatives containing bis(DTC) and mixed DTC-dithiocarbonate ligands. These are the first organoruthenium complexes of such ligands. The reaction of monophosphines with 2a resulted in monochlorido substitution, whereas the analogous reaction with 3 resulted in displacement of both chlorido ligands and reduction of the metal center to RuII. Reduction at Ru was also observed in the reaction of 2a with [CpCr(CO)3]2. Of these complexes, only 2 and 3 are air-stable in the solid state for an extended period. All of the complexes have been spectrally characterized, and selected compounds are also crystallographically characterized.

Discrete copper(i) clusters with Cu6P6Se6 and Cu6P4Se6 cores

The reactions of chalcogenophosphinites with copper(I) metal salts are shown to yield highly stable, multi-metallic copper-chalcogen based clusters with novel topologies.