Juan F. Van der Maelen

The chemical and electrochemical oxidation of pyridonate-bridged ruthenium(I) dimers. X-Ray structure of [Ru2(μ-pyO)2(CO)4(pyOH)2] (pyOH = 2-pyridone)

Abstract Chemical and electrochemical studies have shown that the pyridonate-bridged ruthenium(I) dimers [Ru 2 (μ-pyO) 2 (CO) 4 (L) 2 ] ( 1 ) (L = PPh 3 , 1a ; P i Pr 3 , 1b ; or pyOH, 1c ; pyOH = 2-pyridone) can be oxidized to the cationic paramagnetic species [Ru 2 (μ-pyO) 2 (CO) 4 (L) 2 ] + ( 2 ). The species 2 are very unstable at room temperature, decomposing into a mixture of 1 and the ruthenium(II) cations [Ru(pyO)(CO) 2 (L)] + ( 3 ). The latter can be obtained quantitatively by reaction of 1 with two equivalents of oxidant. The structure of complex 1c , which has an oxidant peak in its cyclic voltammogram at an unexpectedly high potential (1.11 versus 0.47 V for 1a and 0.33 V for 1b ), has been determined by X-ray crystallography, revealing the presence of two intramolecular hydrogen bonds between the oxygen. atoms of the bridging and the terminal pyO fragments.

Tri- and binuclear ruthenium carbonyl complexes containing bridging ligands derived from ortho-substituted anilines. A comparative study of their syntheses using RuCl3 · nH2O or [Ru3(CO)12] as starting materials

The trinuclear carbonyl clusters [Ru3(μ-H)(μ,η2-o-HNC6H2Me2NH2)(CO)9] (o-H2NC6H2Me2NH2 = 1,2-diamino-4,5-dimethylbenzene) and [Ru3(μ,η2-o-OC6H4NH2)2(CO)8] (o-HOC6H4NH2 = 2-aminophenol) have been prepared by two alternative synthetic routes which involve (a) thermal reaction of [Ru3(CO)12] with the appropriate ligand or (b) reacton of RuCl3 · nH2O with CO in refluxing 2-methoxyethanol, followed by treatment of the resulting solution with the appropriate ligand in the presence of zinc. However, [Ru3(μ-H)(μ,η2-o-SC6H4NH2)(CO)9] (o-HSC6H4NH2 = 2-aminothiphenol) and [Ru3(μ-H)(μ,η2-o-OC6H4NH2)(CO)9] can only be prepared by method (a), whereas [Ru2(μ,η2-o-SC6H4NH)(CO)6] can only be prepared by method (b). The compound [Ru3(μ-H)(μ,η2-o-SC6H4NH2)(CO)9] has been characterized by X-ray diffraction methods: C15H7NO9Ru3S, orthorhombic, space group Pbca, a = 11.191(5), b = 16.462(5), c = 21.978(2) A, V = 4049(2) A3, Z = 8, T = 293 K, R(F) = 0.043.

QTAIM analysis of the bonding in Mo-Mo bonded dimolybdenum complexes

A number of local and integral topological parameters of the electron density of relevant bonding interactions in the binuclear molybdenum complexes [Mo(2)Cl(8)](4-), [Mo(2)(μ-CH(3)CO(2))(4)], [Mo(2)(μ-CF(3)CO(2))(4)], [Mo(2)(μ-CH(3)CO(2))(4)Br(2)](2-), [Mo(2)(μ-CF(3)CO(2))(4)Br(2)](2-), [Mo(2)(μ-CH(3)CO(2))(2)Cl(4)](2-), [Mo(2)(μ-CH(3)CO(2))(2)(μ-Cl)(2)Cl(4)](2-), and [Mo(2)(μ-Cl)(3)Cl(6)](3-) have been calculated and interpreted under the perspective of the quantum theory of atoms in molecules (QTAIM). These data have allowed a comparison between related but different atom-atom interactions, such as different Mo-Mo formal bond orders, ligand-unbridged versus Cl-bridged, CH(3)CO(2)-bridged, and CF(3)CO(2)-bridged Mo-Mo interactions, and Mo-Cl(terminal) and Mo-Cl(bridge) versus Mo-Br and Mo-O interactions. Calculations carried out using nonrelativistic and relativistic approaches afforded similar results.

Formation of Cyclopentadienyl and Ruthenacyclopentadienyl Derivatives through Ynenyl–Diyne and Ynenyl–Alkyne Couplings onto a Triruthenium Cluster Core

The compound [Ru3(mu-H)(mu3-eta2-ampy)(CO)9] (1; Hampy =2-amino-6-methylpyridine) reacts with diynes RC4R in THF at reflux temperature to give the ynenyl derivatives [Ru3(mu3-eta2-ampy)(mu-eta3-RC...CC-CHR)(mu-CO)2-(CO)6] (2: R=CH2OPh; 3: R=Ph). These products contain a 1,4-disubstituted butynen-3-yl ligand attached to two ruthenium atoms. The compound [Ru3(mu-eta2-ampy)[mu3-eta6-PhCC5(C...CPh)-HPh2](CO)7] (4), which contains an eta5-cyclopentadienyl ring and a bridging carbene fragment, has also been obtained from the reaction of 1 with diphenylbutadiyne. This compound arises from a remarkable [3+2] cycloaddition reaction of a preformed 1,4-diphenylbutynen-4-yl ligand with a triple bond of a second diphenylbutadiyne molecule. The reactivity of the ynenyl derivatives 2 and 3 with diynes and alkynes has been studied. In all cases, compounds of the general formula [Ru3(mu-eta2-ampy)[mu3-eta5-C(=CHR)C=CRCR1=CR2](CO)7] (5-17) have been obtained. They all contain a ruthenacyclopentadienyl fragment formed by coupling of the coordinated ynenyl ligand of 2 (R = CH2OPh) or 3 (R = Ph) with a triple bond of the new reagent (the CR1=CR2 fragment results from the incoming diyne or alkyne reagent). While most of the products derived from 2 have the alkenyl C=CHR fragment with a Z configuration (R cis to Ru), all the compounds obtained from 3 have this fragment with an E configuration. Except 2 and 3, all the cluster complexes described in this article have a five-electron donor ampy ligand attached to only two metal atoms, a coordination mode unprecedented in cluster chemistry.

The addition of protons and metallic electrophiles to the electron-rich RuRu bond of [Ru2(μ,-dan)(CO)4(PiPr3)2]. X-ray structure of [Ru2(μ-AgPPh3)(μ-dan)(CO)4(PiPr3)2][BF4]·CH2Cl2 (dan=1,8-diamidonaphthalene)

Abstract The ruthenium(I) complex [Ru 2 (μ-dan)(CO) 4 (P i Pr 3 ) 2 ] ( 1 ) (dan= 1,8-diamidonaphthalene) reacts with HBF 4 ·OEt 2 , [AuCI(PPh 3 )]/TIPF 6 and AgBF 4 /PPh 3 to give the cationic complexes [Ru 2 (μ-M)(μ- dan)(CO) 4 (P i Pr 3 ) 2 ] + (M=H (2), AuPPh 3 (3), AgPPh 3 ( 4 )), while the reactions with [AuCl(tht)] (tht = tetrahydrothiophene) and AgO 2 CCF 3 give the neutral derivatives [Ru 2 (μ-M)(μ-dan)(CO) 4 (p i pr 3 ) 2 ] (M=AuCI (5), AgO 2 CCF 3 ( 6 )). Complex 1 also reacts with SnCl 2 to give [Ru 2 (μ-SnCle 2 )(μ- dan)(CO) 4 (P i Pr 3 ) 2 ] (7), hut in solution it dissociates SnCI 2 unless a large excess of the latter is present. In all cases, the added electrophiles symmetrically bridge the RuRu bond of complex 1 , as indicated by IR and NMR spectroscopies. The structure of complex 4 has been confirmed by X-ray diffraction methods.

Generating and Trapping Metalla‐N‐Heterocyclic Carbenes

By means of a combined experimental and theoretical approach, the electronic features and chemical behavior of metalla-N-heterocyclic carbenes (MNHCs, N-heterocyclic carbenes containing a metal atom within the heterocyclic skeleton) have been established and compared with those of classical NHCs. MNHCs are strongly basic (proton affinity and pK(a) values around 290 kcal mol(-1) and 36, respectively) with a narrow singlet-triplet gap (around 23 kcal mol(-1)). MNHCs can be generated from the corresponding metalla-imidazolium salts and trapped by addition of transition-metal complexes affording the corresponding heterodimetallic dicarbene derivatives, which can serve as carbene transfer agents.

Mercury-bridged transition-metal clusters. Synthesis of pentanuclear Ru3HgM (M Mo, W, or Co) clusters and X-ray structure of [(Ru3(μ3,η2-ampy)(CO)9)-(μ3-Hg)Co(CO)4] (Hampy 2-amino-6-methylpyridine)

Abstract Redistribution reactions of the compound [Ru 3 (μ-HgCl)(μ 3 ,η 3 -ampy)(CO) 9 ] ( 1 ) (Hampy = 2-amino-6-methylpyridine) with the metal-metal bonded transition-metal dimers [M 2 Cp 2 (CO) 6 ] (M  MO or W) and [CO 2 (CO) 8 ] give a separable mixture of the mixed-metal clusters [{RU 3 (μ 3 ,η 2 -ampy)(CO) 9 }(μ 3 -Hg)ML n ] (ML n  MOCp(CO) 3 ( 2 ), WCp(CO) 3 ( 3 ), Co(CO) 4 ( 4 )) and the corresponding chloro complexes [MClL n ]. The compounds 2–4 contain an Hg-ML n fragment spanning the same Ru-Ru edge as the amido moiety of the ampy ligand, as has been determined by 13 C NMR spectroscopy and, in the case of complex 4 , by an X-ray diffraction study. Crystal data for 4 : triclinic, space group P −1 , a = 9.598(3), b = 11.817(3), c = 12.835(6) A, α = 76.40(3), β = 75.34(4), γ = 83.34(3)°, V = 1366(1) A 3 , Z = 2; R = 0.0359, R W = 0.0362 for 3508 observed reflections and 372 variables.

Derivative Chemistry of [Ru2(μ-bdt)(CO)6], a Binuclear Ruthenium(I) Carbonyl Complex Containing a Bridging Benzene-1,2-dithiolate Ligand

The known dithiolate-bridged ruthenium(I) complex [Ru2(μ-bdt)(CO)6] (1) (bdt = benzene-1,2-dithiolate) has been prepared in fair yield (55%) by the sequential treatment of RuCl3·nH2O with carbon monoxide, benzene-1,2-dithiol and zinc in a one-pot reaction. Complex 1 reacts readily with monodentate phosphanes to give, stepwise, the penta- and tetracarbonyl derivatives [Ru2(μ-bdt)(CO)6–n(PR3)n] (n = 1, 2; R = Ph, Cy, iPr). However, the reaction of 1 with one equivalent of bis(diphenylphosphanyl)methane (dppm) affords a mixture of complex 1 and the disubstituted derivative [Ru2(μ-bdt)(CO)4(η1-dppm)2], in which the dppm ligands are monodentate. This mixture is subsequently transformed into a polymeric material of formula [{Ru2(μ-bdt)(CO)4}(μ-dppm)]n, which consists of binuclear {Ru2(μ-bdt)(CO)4} units linked to each other by bridging dppm ligands. The use of two equivalents of dppm leads to [Ru2(μ-bdt)(CO)4(η1-dppm)2] in quantitative yield. The X-ray diffraction structure of [Ru2(μ-bdt)(CO)4(PiPr3)2] (3c) confirms that the phosphane ligands are located in axial positions, cis to both sulfur atoms, and that the Ru–Ru distance is short [2.6753(7) A]. A comparative study of the reactivity of complexes 1 and 3c with the electrophiles H+, [Au(PPh3)]+, and HgCl2 has allowed the isolation of the derivatives [Ru2(μ-H)(μ-bdt)(CO)6–n(PiPr3)n][BF4] (n = 0, 2), [Ru2Au(μ-bdt)(CO)6–n(PiPr3)n(PPh3)][BF4] (n = 0, 2) and [Ru2HgCl2(μ-bdt)(CO)6–n(PiPr3)n] (n = 0, 2), respectively.

2-(Methylamido)pyridine–Borane: A Tripod κ3-N,H,H Ligand in Trigonal Bipyramidal Rhodium(I) and Iridium(I) Complexes with an Asymmetric Coordination of Its BH3 Group

The complexes [M(κ(3)-N,H,H-mapyBH3)(cod)] (M = Rh, Ir; HmapyBH3 = 2-(methylamino)pyridine-borane; cod = 1,5-cyclooctadiene), which contain a novel anionic tripod ligand coordinated to the metal atom through the amido N atom and through two H atoms of the BH3 group, were prepared by treating the corresponding [M2(μ-Cl)2(cod)2] (M = Rh, Ir) precursor with K[mapyBH3]. X-ray diffraction studies and a theoretical Quantum Theory of Atoms in Molecules analysis of their electron density confirmed that the metal atoms of both complexes are in a very distorted trigonal bipyramidal coordination environment, in which two equatorial sites are asymmetrically spanned by the H-B-H fragment. While both 3c-2e BH-M interactions are more κ(1)-H (terminal σ coordination of the B-H bond) than κ(2)-H,B (agostic-type coordination of the B-H bond), one BH-M interaction is more agostic than the other, and this difference is more marked in the iridium complex than in the rhodium one. This asymmetry is not evident in solution, where the cod ligand and the BH3 group of these molecules participate in two concurrent dynamic processes of low activation energies (variable-temperature NMR and density functional theory studies), namely, a rotation of the cod ligand that interchanges its two alkene fragments (through a square pyramidal transition state) and a rotation of the BH3 group about the B-N bond that equilibrates the three B-H bonds (through a square planar transition state). While the cod rotation has similar activation energy in 2 and 3, the barrier to the BH3 group rotation is higher in the iridium complex than in the rhodium one.

Selective insertion of mercury(II) halides into the ruthenium–mercury bonds of trinuclear Ru2Hg clusters

The complex [Ru2(µ-dan)(CO)4(PPri3)2]1(H2dan = naphthalene-1,8-diamine) reacts with HgX2(X = Cl, Br or I) to give the trinuclear clusters [(1)HgX2] which react with HgZ2(Z = Cl, Br or I) to form the insertion products [(1)Hg(µ-Z)2HgX2] only when Z is more electronegative than X, otherwise the addition products [(1)Hg(µ-X)2HgZ2] are obtained; the X-ray structure of [(1)Hg(µ-Cl)2HgCl2] has been determined.