Chemistry of ruthenium with some phenolic ligands: synthesis, structure and redox properties (original) (raw)
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Chemistry of some ruthenium phenolates: synthesis, structure and redox properties
Polyhedron, 2000
Reaction of three phenolate ligands, viz. 2,4,6-tribromophenol (HL 1 , where H stands for the phenolic proton), 2-nitrophenol (HL 2) and 2,4,6-trinitrophenol (HL 3 O), with [Ru(PPh 3) 3 Cl 2 ] in a 2:1 molar ratio in the presence of a base gives complexes of type [Ru(PPh 3) 2 (L) 2 ] (L= L 1 , L 2 and L 3). The 2,4,6-tribromophenolate ligand (L 1) binds to ruthenium as a bidentate O,Br-donor, while the 2-nitrophenolate ligand (L 2) acts as a bidentate O,O-donor. 2,4,6-Trinitrophenol (HL 3 O) undergoes oxygen loss from one nitro group at the ortho position and coordinates to ruthenium in the 2-nitroso-4,6-dinitrophenolate (L 3) form through the nitroso nitrogen and phenolate oxygen. The structures of the [Ru(PPh 3) 2 (L 1) 2 ] and [Ru(PPh 3) 2 (L 3) 2 ] complexes have been solved by X-ray crystallography. In [Ru(PPh 3) 2 (L 1) 2 ] the coordination sphere around ruthenium is O 2 P 2 Br 2 with a trans-cis-cis disposition of the three sets of donor atoms, respectively. In [Ru(PPh 3) 2 (L 3) 2 ] ruthenium has a N 2 O 2 P 2 coordination sphere with a cis-cis-trans arrangement of the three sets of donor atoms, respectively. The [Ru(PPh 3) 2 (L) 2 ] complexes are diamagnetic (low-spin d 6 , S=0) and in acetonitrile solution show intense MLCT transitions in the visible region. Cyclic voltammetry on the [Ru(PPh 3) 2 (L) 2 ] complexes shows a reversible ruthenium(II)-ruthenium(III) oxidation within 0.63-0.71 V versus SCE followed by an irreversible ruthenium(III)-ruthenium(IV) oxidation near 1.5 V versus SCE.
Polyhedron, 2005
Ruthenium (II) complexes with the hemilabile ligand Ph 2 PCH 2 P(O)Ph 2 (dppmO) were obtained and characterized by 31 P{ 1 H} NMR, IR and cyclic voltammetry. The reaction of the compound tcc-[RuCl 2 (g 2 -dppmO) 2 ] with carbon monoxide yielded the complexes [RuCl 2 (CO)(g 1 ,g 2 -dppmO) 2 ] and [RuCl(CO)(g 2 -dppmO) 2 ]PF 6 . For the tcc-[RuCl 2 (g 2 -dppmO) 2 ] and [RuCl 2 (CO)(g 1 ,g 2 -dppmO) 2 ] species, two dimensional NMR analyses 31 P-31 P gCOSY, 13 C-1 H HSQC, 1 H-31 P HMBC were performed. Based on the resulting chemical shifts, coupling constants and correlations between 1 H, 13 C and 31 P spectra it was possible to reveal the structures of these complexes in solution. The structure of the tcc-[RuCl 2 (g 2 -dppmO) 2 ] complex was determined by X-ray diffraction, confirming the NMR results. The mer-[RuCl 3 (g 1 ,g 2 -dppmO) 2 ] complex was characterized by EPR and its crystal structure was also established by X-ray diffraction. The isomerization of tcc-[RuCl 2 (g 2 -dppmO) 2 ] into cct-[RuCl 2 (g 2 -dppmO) 2 ] was followed by UV-Vis spectroscopy and 31 P{ 1 H} NMR.
Syntheses and Structures of Ruthenium Complexes Containing a Ru-H-Tl Three-Center-Two-Electron Bond
Angewandte Chemie (International ed. in English), 2018
Treatment of CpRuH(PP) (PP=dppm, dppe) with TlPF produced [CpRu(H)(Tl)(PP)]PF . X-ray diffraction and computational studies suggest that the complexes contain a Ru-H-Tl 3c-2e bond and can be viewed as the first σ-complexes of period 6 main-group hydrides [CpRu{η -(H-Tl)}(PP)]PF or [Tl{η -H-RuCp(PP)}]PF . The complexes can be stored as a solid at room temperature for days without appreciable decomposition, but are unstable in solution and evolved to the trimetallic complexes [{CpRu(PP)} (μ-Tl)]PF .
Synthesis, spectral, and redox properties of three triply bridged complexes of ruthenium
Inorganic Chemistry, 1989
Syntheses are described for the ligand-bridged complexes [(tpm)Ru"'(p-O)(p-L),Ru"'(tpm)"+ (L = 02P(0)(OH), n = 0 (1); L = 0 2 C 0 , n = 0 (2); L = 02CCH3, n = 2 (3); tpm is the tridentate, facial ligand tris(1-pyrazoly1)methane. The X-ray crystal structure of [(tpm)Ru(p-O)(p-O2P(O)(0H)),Ru(tpm)].8H2O was determined from three-dimensional X-ray counter data. The com lex crystallizes in the trigonal space group P3221 with three molecules in a cell of dimensions (I = 18.759 (4) A and c = 9.970 ( 6 ) 1. The structure was refined to a weighted R factor of 0.042 based on 1480 independent reflections with I 1 3 4 . The structure reveals that the complex consists of two six-coordinate ruthenium atoms that are joined by a p-oxo bridge (rRu4 = 1.87 A; LRuORu = 1 2 4 . 6 O ) and two p-hydrogen phosphato bridges (average rRu+ = 2.07 A) which are capped by two tpm ligands.
RuCl2{PPh2(2,6Me2C6H3)}2]: A Neutral 14Electron Ruthenium(II) Complex with Two Agostic Interactions
Angewandte Chemie-international Edition, 1999
Coordinatively unsaturated transition metal complexes, which play a key role in many catalytic processes, have been often obtained with bulky tertiary phosphanes (PR 3 ) as ligands that provide steric protection to the empty coordination sites at the metal. The steric crowding forces the R group of the ligand in close proximity to the metal center to induce an agostic interaction [1] between a CÀH bond in the R group and the metal atom, thus preventing dimerization or solvent coordination. Ruthenium(ii) complexes with small phosphanes are generally six-coordinate 18-electron species of the type [RuX 2 (PR 3 ) 4 ] (X halide), whereas with the bulky triarylphosphanes five-coordinate 16-electron complexes such as [RuCl 2 (PPh 3 ) 3 ] are formed. [2] La Placa and Ibers noted that the close approach of one ortho-phenyl hydrogen atom to the metal effectively blocks a coordination site at the ruthenium center. [3] It can be anticipated that when the ortho-hydrogen atom of the phenyl rings of PPh 3 are substituted with methyl groups, stronger contacts would occur; the CH 3 group is forced close to metal center, and an agostic interaction is favored. With this in mind, we have been investigating ruthenium(ii) complexes with ortho-methyl-substituted arylphosphane ligands.
Organometallics, 2002
Reaction of diphenyl[2.2]paracyclophanylphosphine, rac-PPh 2 (C 16 H 15 ) (1), with [Ru(ηarene)Cl 2 ] 2 (where arene ) C 6 H 6 , [2.2]paracyclophane (C 16 H 16 )) in a 2:1 ratio affords the half-sandwich complexes Ru(η-arene)Cl 2 {PPh 2 (C 16 H 15 )} (arene ) C 6 H 6 (2), C 16 H 16 (3)) in high yield. In solution, the structures of 2 and 3 have been probed and assigned using 2D NMR spectroscopy and the structure of the [2.2]paracyclophane derivative, 3, has been established in the solid-state by single-crystal X-ray diffraction. Cyclic voltammetry and steady-state voltammetry of 2 in 0.25 M [ n Bu 4 N][PF 6 ]/CH 2 Cl 2 shows that the complex undergoes a chemically reversible, one-electron oxidation and an irreversible, two-electron reduction. The voltammetry of the related complex [Ru(η 6 -C 6 H 6 )Cl 2 (PPh 3 )] (4), recorded under analogous conditions, is similar both in terms of the processes displayed and the potentials at which they occur. a Atom labels are as shown; the CH2 protons labeled "a" correspond to those on the same side of cyclophane as the P atom, and those labeled "b" are on the opposite side. Resonances are given in units of ppm and J values in Hz.
J Organomet Chem, 1994
The reaction between 4-methoxyphenol and Ru,(CO)~~ in cyclohexane has been investigated and found to afford a hexaruthenium 'raft' cluster Ru,(p-H)&-q7-0C~H~OMe-4)(CO& (3a), together with tetraruthenium clusters incorporating three (Ru&-OC,H,OMe-4),(@lX~-OCsH.,OMe-4XCO),, (3bN or four (Ru&-OC,H,OMe-4),(LL-OC,H,OMe-4),(CO~u, (3~)) aryloxo ligands; similarly, reaction of Ru,(CO),, with 2-naphthol afforded the analogous Ru,(~~-H)~(IL~-~'-OC~~H~XCO)~~ &I), Ru&-0C,,H7)2(11-CIX~-OC10H7MC0)10 (4b) and Ru.,(~~-OC~~H~)~(~-OC~~H~)~(CO~~,, (4e). The source of chloride in 3b and 4b is believed to be carbon tetrachloride contaminant in the cyclohexane. An X-ray diffraction study reveals that 3b contains an Ru,(CO), unit linked to an Ru(CO), moiety by two asymmetric triply-bridging and one asymmetric doubly-bridging 4methox-yphenoxo ligands, and an asymmetric doubly-bridging chloro ligand; this interaction is strongly suggestive of a higher oxidation state ruthenium linked to a trinuclear cluster of formally zero oxidation state. The dynamic 13C NMR spectra of 4c have been recorded, and are consistent with restricted rotation about the Ar-0 linkage of the p+oordinated naphthoxo ligands at low temperature.