Article pubs.acs.org/Organometallics
Reactivity of a Bis(N-heterocyclic carbene) with Ruthenium Carbonyl. Synthesis of Mono- and Trinuclear Derivatives and Ligand Modification via C−H Bond Activation Javier A. Cabeza,*,† Marina Damonte,† and Enrique Pérez-Carreño‡ †
Departamento de Quı ́mica Orgánica e Inorgánica-IUQOEM, Universidad de Oviedo-CSIC, E-33071 Oviedo, Spain Departamento de Quı ́mica Fı ́sica y Analı ́tica, Universidad de Oviedo, E-33071 Oviedo, Spain
‡
S Supporting Information *
ABSTRACT: The bis(N-heterocyclic carbene) 1,1′-dimethyl-3,3′(o-xylylene)diimidazol-2,2′-diylidene (MeImCH2C6H4CH2ImMe) reacted with [Ru3(CO)12] at room temperature, in a 3/1 molar ratio, to give the mononuclear derivative [Ru(κ 2 C 2 MeImCH2C6H4CH2ImMe)(CO)3] (1), which contains a chelating bis(NHC) ligand. However, the use of a 1/1 ratio of the reactants led to the trinuclear cluster [Ru3(μ-κ2C2MeImCH2C6H4CH2ImMe)(CO)10] (2), which contains an edgebridging bis(NHC) ligand and which, upon heating in refluxing THF, underwent a double C(sp3)−H bond activation process to give the dihydride derivative [Ru3(μ-H)2(μ3-κ3C3MeImCC6H4CH2ImMe)(CO)8] (3).
T
[Ru3(CO)12] with more than 1 equiv of the corresponding NHC led to inseparable mixtures of products or to mononuclear derivatives.4−8 This fact and the absence in the chemical literature of reports dealing with reactions of [Ru3(CO)12] with bis(NHC) ligands prompted us investigate this type of reactions. We now report the successful preparation of tri- and mononuclear compounds of the types [Ru3(NHC)2(CO)10] and [Ru(NHC)2(CO)3] by reacting [Ru3(CO) 12] with appropriate amounts of the bis(NHC) 1,1′-dimethyl-3,3′-(oxylylene)diimidazol-2,2′-diylidene, hereafter abbreviated as MeImCH2C6H4CH2ImMe, showing also that the disubstituted triruthenium cluster is prone to undergo an easy thermally induced transformation that involves the activation of both C(sp3)−H bonds of one CH2 group of the original bis(NHC) ligand. MeImCH2C6H4CH2ImMe has been previously used as a chelating ligand in mononuclear palladium(II) complexes.20
he past decade has witnessed a tremendous advance of the N-heterocyclic carbene (NHC) chemistry of transitionmetal cluster complexes.1 This research field, which was initiated in 1977 with Lappert’s synthesis of [Ru3(CO)11(Et2H2Im)] (Et2H2Im = 1,3-diethylimidazolin-2ylidene),2 has been mostly developed by the research groups of Whittlesey,3,4 Cole,5 and Wang6,7 and also by our group,8−15 who have reported studies involving triruthenium and triosmium clusters derived from 1,3-disubstituted imidazol-2ylidenes3−11,14,15 (RImR), pyrid-2-ylidenes,12 and pyrimid-2ylidenes.13 The reactions of some NHCs with [Ru4(μH)4(CO)12] have also been communicated.16,17 These studies have shown that, as a consequence of the high basicity of the NHC ligands, the clusters [Ru3(NHC)(CO)11], which are the initial products of the reactions of NHCs with [Ru3(CO)12] in 1/1 molar ratio,3,7,8 are prone to undergo easy C−H bondcleavage processes upon thermal activation to give hydrido derivatives that contain NHC-derived cyclometalated bridging ligands.3,6,7,9−12 On the other hand, although the coordination chemistry of bi-, tri-, or polydentate ligands constituted by at least one NHC moiety has already been extensively studied,18 only a few works have hitherto been published involving such ligands and ruthenium carbonyl clusters. They implicate NHC-functionalized pyridine,14,16b phosphine,15,16b indene,6 alkene,7 thioether,15b,16b and thiolate19 ligands, but not ligands containing two coordinatable NHC fragments, hereafter denoted as bis(NHC) ligands. Quite a few monosubstituted complexes of the type [Ru3(NHC)(CO)11] are already known,1 but simple disubstituted complexes of the type [Ru3(NHC)2(CO)10] have never been prepared. In fact, it has been reported that the reactions of © 2012 American Chemical Society
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RESULTS AND DISCUSSION Reactions of [Ru3(CO)12] with MeImCH2C6H4CH2ImMe. The treatment of [Ru 3 (CO) 1 2 ] with 3 equiv of MeImCH2C6H4CH2ImMe (prepared in situ by deprotonating the bis(imidazolium) salt [MeHImCH2C6H4CH2ImHMe]Br2 with K[N(SiMe3)2]) in THF at room temperature led to the air-sensitive mononuclear derivative [Ru(κ2C2MeImCH2C6H4CH2ImMe)(CO)3] (1), which was isolated as a yellow solid (Scheme 1). Its mononuclear nature was Received: October 3, 2012 Published: November 14, 2012 8355
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spin d8 complexes.21 All the hitherto known types of mononuclear ruthenium(0) complexes containing NHC ligands, namely [Ru(NHC)(CO)4],5 [Ru(NHC)2(CO)3],4 and [Ru(NHC-PR2)(CO)3],15 have at least4 one NHC ligand (or fragment) in a tbp axial coordination site. The treatment of [Ru3(CO)12] with an equimolar amount of MeImCH2C6H4CH2ImMe in THF at room temperature led to the trinuclear cluster [Ru3(μ-κ2C2-MeImCH2C6H4CH2ImMe)(CO)10] (2), which was isolated as a red solid after a chromatographic workup (Scheme 1). The molecular structure of compound 2 was determined by X-ray crystallography (Figure 2 and Table 1). The molecule
Scheme 1
indicated by its IR spectrum, which only contains three bands in the 1974−1856 cm−1 region. The low wavenumbers of its νCO absorptions indicate that its CO ligands are attached to an electron-rich metal atom, reflecting that the bis(NHC) ligand of 1 is slightly less electron donating than both NHC ligands of [Ru(NHC)2(CO)3] (NHC = 1,3-bis(isopropyl)-2-ylidene; νCO absorptions in the range 1970−1841 cm−1)4 but more electrondonating than the ditopic ligands of [Ru(NHC-PR2)(CO)3] complexes (νCO absorptions in the range 1998−1883 cm−1).15 As expected for a mononuclear pentacoordinate complex, compound 1 is fluxional in solution (even at −80 °C), since its 13 C NMR spectrum only shows one resonance for the CO ligands and eight resonances for the MeImCH2C6H4CH2ImMe ligand. The 13C NMR resonance of the Ccarbene atoms of 1 is observed at 188.3 ppm. We could not get crystals of 1 suitable for X-ray diffraction analysis, but its minimum-energy structure was deduced by DFT calculations. Figure 1 shows that the NHC fragments of the MeImCH2C6H4CH2ImMe ligand are placed at axial and equatorial coordination sites of a trigonal bipyramidal (tbp) ligand arrangement. We also examined other geometries as input models, but they all converged to the tbp structure shown in Figure 1 after optimization. In classical ligand-field theory, a trigonal-bipyramidal structure is energetically favored for low-
Figure 2. X-ray diffraction molecular structure of compound 2 (only one of the two independent molecules found in the asymmetric unit is represented; CO ligands and H atoms are not labeled).
Table 1. Selected Interatomic Distances (Å) in One of the Two Independent Cluster Molecules Found in the Asymmetric Unit of 2·0.5CH2Cl2 Ru1−Ru2 Ru1−Ru3 Ru2−Ru3 C1−Ru2 C1−N1 C1−N2 C2−N1 C3−N1 C3−C4 C4−N2 C5−N2
2.8774(4) 2.8923(4) 2.9187(4) 2.094(3) 1.366(5) 1.371(5) 1.456(5) 1.384(5) 1.329(6) 1.396(5) 1.468(5)
C5−C6 C6−C11 C11−C12 C12−N3 C13−N3 C13−C14 C14−N4 C15−Ru3 C15−N3 C15−N4 C16−N4
1.516(5) 1.391(5) 1.517(5) 1.472(5) 1.384(5) 1.342(6) 1.384(5) 2.090(4) 1.363(4) 1.366(5) 1.468(4)
formally results from the replacement of the bis(NHC) ligand for two adjacent equatorial CO ligands of [Ru3(CO)12] on different metal atoms of the Ru3 triangle. In the solid state, 2 has an approximate (noncrystallographic) C2 symmetry, with the 2-fold axis passing through the unbridged Ru atom and the center of the bridged Ru−Ru edge. The 1H and 13C NMR spectra of 2 suggest that this symmetry is maintained in solution, since they only contain the resonances expected for half of the molecule. The 13C NMR resonance of the Ccarbene atoms of 2 is observed at 174.5 ppm. Analogous trinuclear ligand-bridged derivatives have been previously prepared from reactions of [Ru3(CO)12] with ditopic NHC-phosphine ligands.15 However, as reactions of
Figure 1. DFT-optimized molecular structure of compound 1 (CO ligands and H atoms are not labeled). Selected bond lengths (Å) and angles (deg): Ru1−C1 = 2.148, Ru1−C15 = 2.161; C1−Ru1−C15 = 98.032. 8356
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MeIm and C6H4CH2ImMe fragments of the bridging ligand. The latter fragment is also bound to the Ru2 metal atom through its carbenic atom (C1). Two edges of the metal triangle, Ru1−Ru2 and Ru2−Ru3, are spanned by hydride ligands. The Ru2−Ru3 edge, 3.0354(4) Å, is considerably longer than the other two edges: Ru1−Ru2 = 2.7939(4) Å and Ru1−Ru3 = 2.8260(4) Å. The cluster shell is completed by eight terminal carbonyl ligands. The solution IR and NMR spectra of 3 are in complete agreement with its solid-state structure. The IR spectrum clearly shows that this complex only has terminal CO ligands. The 13C NMR resonances of the Cbridging and the two Ccarbene atoms of 3 are observed at 125.6, 170.0, and 178.0 ppm, respectively. In addition to the signals expected for the MeImCC6H4CH2ImMe ligand, the 1H NMR spectrum of 3 also contains the resonances of two hydrides (at −11.73 and −16.94 ppm). It has been previously shown that for triruthenium clusters containing monodentate asymmetric NHC ligands of the type RImMe, the NHC N-methyl group is generally preferred over the N-R group to become involved in C−H bond activation reactions.7,9 An analogous behavior has also been observed for the bidentate phosphine-NHC ligand Ph2PCH2CH2ImMe, which reacts with [Ru3(CO)12] to give [Ru3(μ-H)2(μ3-κ3P,C2Ph2PCH2CH2ImCH)(CO)8] under the appropriate reaction conditions (THF, 70 °C).15a However, the phosphine-NHC cluster [Ru3(μ-H)2(μ3-κ3P,C2-Ph2PC6H4CImMe)(CO)8]15b arises from the activation of the C−H bonds of the CH2 group of the Ph2PC6H4CH2ImMe ligand, but the bidentate pyridine-NHC ligands MepyCH2ImMe and HpyCH2ImMe do not activate any C−H bond of the groups that are directly attached to their NHC fragment when they react with [Ru3(CO)12] at elevated temperatures (Scheme 1).14
[Ru3(CO)12] with more than 1 equiv of an NHC lead to unseparable mixtures of products or to mononuclear derivatives,4−8 it is noteworthy that compound 2 is the first isolated complex that arises from the substitution of two carbonyl ligands of [Ru3(CO)12] by NHCs. The bridging attachment of MeImCH2C6H4CH2ImMe in 2, a coordination mode hitherto unknown for this ligand,20 has to be claimed as responsible for the stability of this cluster at room temperature. Thermolysis Reactions. Prompted by the fact that the basicity of NHC ligands enhances the tendency of the metal atoms to which they are attached to participate in oxidative addition reactions, including intramolecular C−H and C−N bond activations,3,6,7,9−12,22 we investigated the thermolysis of compounds 1 and 2, expecting that the rigidity imposed by the CH2C6H4CH2 linker of the bis(NHC) ligand and its high basicity could lead to interesting reaction products. The thermolysis of compound 1 in refluxing THF for 2 h led to a mixture of products that could not be separated or characterized. However, an analogous treatment of compound 2 led to the quantitative formation of the face-capped doubly C−H activated trinuclear derivative [Ru3(μ-H)2(μ3-κ3C3MeImCC6H4CH2ImMe)(CO)8] (3), which was isolated as a yellow solid (Scheme 1). The molecular structure of 3 was determined by an X-ray diffraction analysis (Figure 3 and Table 2). This complex
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CONCLUDING REMARKS The synthesis of compounds 1 and 2 has demonstrated that the bis(NHC) MeImCC6H4CH2ImMe can act not only as a chelating ligand (e.g., in 1) but also as a bridging ligand (e.g., in 2), the latter being a hitherto unknown coordination mode for this ligand. Its bridging coordination in 2 is in fact responsible for the stability of this complex at room temperature, since, so far, all attempts to prepare complexes of the type [Ru3(NHC)2(CO)10], containing monodentate NHC ligands, have been unsuccessful. Compound 1 decomposes to a mixture of uncharacterized products upon heating in refluxing THF. However, under similar reaction conditions, compound 2 evolves toward 3 + 2 CO through a process that involves the activation of both C−H bonds of a ligand CH2 group. No doubt, this reactivity is a consequence of two factors: (a) the high basicity of the bis(NHC) ligand, which favors its coordination under mild reaction conditions and enhances the tendency of the metal atoms to participate in oxidative addition reactions, and (b) its chelating behavior, which allows the placement of a ligand CH2 group in close proximity to the metal atoms, while it separates its N-methyl groups from the metal atoms.
Figure 3. X-ray diffraction molecular structure of compound 3 (CO ligands and organic H atoms are not labeled).
Table 2. Selected Interatomic Distances (Å) in Compound 3 Ru1−Ru2 Ru1−Ru3 Ru2−Ru3 C1−Ru2 C1−N1 C1−N2 C2−N1 C3−N1 C3−C4 C4−N2 C5−N2 C5−C6
2.7939(4) 2.8260(4) 3.0354(4) 2.065(4) 1.357(5) 1.352(5) 1.455(6) 1.388(5) 1.348(7) 1.376(5) 1.467(5) 1.506(6)
C6−C11 C11−C12 C12−Ru1 C12−Ru2 C12−N3 C13−N3 C13−C14 C14−N4 C15−Ru3 C15−N3 C15−N4 C16−N4
1.400(5) 1.525(5) 2.183(4) 2.178(4) 1.484(5) 1.392(5) 1.348(6) 1.387(6) 2.064(4) 1.355(5) 1.366(5) 1.464(5)
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EXPERIMENTAL SECTION
General Procedures. Solvents were dried over sodium diphenyl ketyl (hydrocarbons, THF) of CaH2 (dichloromethane) and distilled under nitrogen before use. The reactions were carried out under nitrogen, using Schlenk−vacuum line techniques, and were routinely monitored by solution IR spectroscopy (carbonyl stretching region)
contains a MeImCC6H4CH2ImMe ligand capping a face of the ruthenium triangle in such a way that the Ru3 atom is attached to the carbenic atom (C15) of an MeIm fragment while the Ru1−Ru2 edge is spanned by a C atom (C12) that links the 8357
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measurement, and refinement data is given in Table 3. Diffraction data were collected on an Oxford Diffraction Xcalibur Onyx Nova
and spot TLC on silica gel. The dibromide salt [MeHImCH2C6H4CH2ImHMe]Br2 was prepared as described elsewhere.20 All remaining starting reagents were purchased from commercial sources. All reaction products were vacuum-dried for several hours prior to being weighed and analyzed. IR spectra were recorded in solution on a Perkin-Elmer Paragon 1000 FT spectrophotometer. NMR spectra were run on Bruker DPX-300 or AV-400 instruments. Microanalyses were obtained from the University of Oviedo Analytical Service. FAB mass spectra were obtained from the University of A Coruña Mass Spectrometric Service; data given refer to the most abundant molecular ion isotopomer. [Ru(κ2C2-MeImCH2C6H4CH2ImMe)(CO)3] (1). A toluene solution of K[N(SiMe3)2] (2.3 mL, 0.5 M, 1.150 mmol) was added to a suspension of [MeHImCH2C6H4CH2ImHMe]Br2 (240 mg, 0.560 mmol) in THF (30 mL). After the mixture was stirred for 30 min, finely powdered [Ru3(CO)12] (108 mg, 0.169 mmol) was added. This mixture was stirred at room temperature for 40 min. The color changed from orange to yellow. The solvent was removed under reduced pressure, and the residue was extracted into toluene (2 × 20 mL). Solvent removal led to compound 1, which was isolated as an airsensitive yellow solid (240 mg, 94%). Anal. Calcd for C19H18N4O3Ru (451.4): 50.55; H, 4.02; N, 12.41. Found: C, 50.61; H, 2.04; N, 12.37. No (+)-FAB mass spectrum could be obtained. IR (toluene, cm−1): νCO 1974 (s), 1880 (s), 1856 (vs). 1H NMR (acetone-d6, 293 K, 300.1 MHz, ppm): δ 7.53 (dd, J = 5.5, 3.4 Hz, 2 H), 7.39 (dd, J = 5.5, 3.4 Hz, 2 H), 7.34 (d, J = 2.0 Hz, 2 H), 7.06 (d, J = 2.0 Hz, 2 H), 5.63 (d, J = 14.5 Hz, 2 H), 4.60 (d, J = 14.5 Hz, 2 H), 4.02 (s, 6 H). 13C{1H} and DEPT NMR (acetone-d6, 100.1 MHz, 293 K): δ 219.1 (COs), 188.3 (C), 138.0 (C), 132.6 (CH), 129.8 (CH), 124.7 (CH), 121.7 (CH), 54.0 (CH2), 40.8 (CH3). [Ru3(μ-κ2C2-MeImCH2C6H4CH2ImMe)(CO)10] (2). A toluene solution of K[N(SiMe3)2] (680 μL, 0.5 M, 0.340 mmol) was added to a suspension of [MeHImCH2C6H4CH2ImHMe]Br2 (70 mg, 0.163 mmol) in THF (30 mL). After the mixture was stirred for 20 min, finely powdered [Ru3(CO)12] (104 mg, 0.163 mmol) was added. This mixture was stirred at room temperature for 23 h. The color changed from orange to red. The solvent was removed under reduced pressure, and the crude reaction mixture was separated by column chromatography on silica gel (2 × 15 cm, packed in hexane). Dichloromethane eluted compound 2, which was isolated as a redorange solid upon solvent removal (55 mg, 40%). Anal. Calcd for C26H18N4O10Ru3 (849.7): 36.75; H, 2.14; N, 6.59. Found: C, 36.86; H, 2.16; N, 6.52. (+)-FAB MS: m/z 851 [M]+. IR (CH2Cl2, cm−1): νCO 2066 (m), 2001 (m), 1985 (vs). 1H NMR (CD2Cl2, 293 K, 300.1 MHz, ppm): δ 7.42 (s, br, 4 H), 6.92 (d, J = 1.8 Hz, 2 H), 6.63 (d, J = 1.8 Hz, 2 H), 4.70 (s, br, 4 H), 3.99 (s, 6 H). 13C{1H} and DEPT NMR (CD2Cl2, 100.1 MHz, 293 K): δ 214.0 (COs), 174.5 (C), 132.8 (C), 132.2 (CH), 129.7 (CH), 124.5 (CH), 120.8 (CH), 54.7 (CH2), 40.1 (CH3). [Ru3(μ-H)2(μ3-κ3C3-MeImCC6H4CH2ImMe)(CO)8] (3). A THF solution (30 mL) of compound 1 (115 mg, 0.135 mmol) was stirred at reflux temperature for 2 h. The color changed from red to yellow. The solvent was removed under reduced pressure, and the solid residue was washed with hexane (2 × 10 mL) to give compound 3 as a yellow solid (98 mg, 92%). Anal. Calcd for C24H18N4O8Ru3 (793.6): C, 36.32; H, 2.29; N, 7.06. Found: C, 36.35; H, 2.33; N, 7.02 (+)-FAB MS: m/z 795 [M]+. IR (CH2Cl2, cm−1): νCO 2063 (s), 2024 (vs), 2004 (vs), 1975 (m), 1945 (m). 1H NMR (CD2Cl2, 293 K, 300.1 MHz, ppm): δ 7.64 (m, 1 H), 7.19 (m, 1 H), 7.10 (dd, J = 7.6, 1.4 Hz, 1 H), 6.95 (m, 1 H), 6.95 (d, J = 1.9 Hz, 1 H), 6.77 (d, J = 1.9 Hz, 1 H), 6.37 (d, J = 1.9 Hz, 1 H), 6.16 (d, J = 14.0 Hz, 1 H), 5.99 (d, J = 1.9 Hz, 1 H), 4.53 (d, J = 14.0 Hz, 1 H), 3.76 (s, 3 H), 3.58 (s, 3 H), −11.73 (d, J = 1.5 Hz, 1 H), −16.94 (d, J = 1.5 Hz, 1 H). 13C{1H} and DEPT NMR (CD2Cl2, 100.1 MHz, 293 K): δ 204.6 (CO), 204.1 (CO), 202.6 (CO), 200.9 (CO), 200.6 (CO), 199.7 (CO) 193.7 (CO), 187.0 (CO), 170.0 (C), 169.1 (C), 157.5 (C), 139.8 (CH), 133.5 (C), 129.2 (CH), 128.7 (CH), 125.6 (C), 124.9 (CH), 122.8 (CH), 121.6 (CH), 119.9 (CH), 118.5 (CH), 55.2 (CH2), 40.0 (CH3), 38.4 (CH3). X-ray Diffraction Analysis. Crystals of 2·0.5CH2Cl2 and 3 were analyzed by X-ray diffraction methods. A selection of crystal,
Table 3. Crystal, Measurement, and Refinement Data for the Compounds Studied by X-ray Diffraction formula fw cryst syst space group a, Å b, Å c, Å α, β, γ, deg V, Å3 Z F(000) Dcalcd, g cm−3 μ(Cu Kα), mm−1 cryst size, mm T, K θ range, deg min./max. h, k, l no. of collected rflns no. of unique rflns no. of rflns with I > 2σ(I) no. of params/ restraints GOF on F2 R1 (on F, I > 2σ(I)) wR2 (on F2, all data) min/max Δρ, e Å−3
2·0.5CH2Cl2
3
C26H18N4O10Ru3·(CH2Cl2)0.5 892.12 monoclinic P21/n 18.1595(2) 16.0778(1) 21.4623(2) 90, 108.734(1), 90 5934.25(9) 8 3480 1.997 13.596 0.07 × 0.05 × 0.03 123(2) 2.78−69.98 −15 to +21, −19 to +18, −25 to +22 19 899
C24H18N4O8Ru3 793.63 monoclinic P21/c 13.7947(3) 8.3567(2) 22.6665(5) 90, 97.733(2), 90 2589.2(1) 4 1544 2.036 14.490 0.10 × 0.02 × 0.02 123(1) 3.23−69.98 −16 to +13, −10 to +9, −27 to +20 9138
10 911
4845
8748
4133
800/0
362/0
0.974 0.027
1.003 0.028
0.063
0.074
−0.788/0.601
−0.793/0.510
single-crystal diffractometer, using Cu Kα radiation. Empirical absorption correction was applied using the SCALE3 ABSPACK algorithm as implemented in the program CrysAlisPro RED.23 The structure was solved using the program SIR-97.24 Isotropic and fullmatrix anisotropic least-squares refinements were carried out using SHELXL.25 All non-H atoms were refined anisotropically. The positions of the hydride ligands were calculated with XHYDEX.26 The remaining hydrogen atoms were set in calculated positions and refined riding on their parent atoms. The WINGX program system27 was used throughout the structure determinations. CCDC deposition numbers: 902203 (2·0.5CH2Cl2) and 902204 (3). Computational Details. The molecular structure of compound 1 was optimized by DFT calculations in the gas phase, using the hybrid exchange-correlation functional B3P8628 within the GAUSSIAN-03 program suite.29 The LanL2DZ basis set, with relativistic effective core potentials, was used for the Ru atom.30 The basis set used for the remaining atoms was the standard 6-31G with addition of (d,p)polarization. To determine the structure of compound 1, input models corresponding to various trigonal-bipyramidal and square-basepyramidal ligand arrangements were constructed, but after optimization, they all converged to the same structure (Figure 1), which was confirmed as an energy minimum by a calculation of analytical frequencies. 8358
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Rev. 2009, 109, 3677. (e) Kühl, O. Chem. Soc. Rev. 2007, 36, 592. (f) Liddle, S. T.; Edworthy, I. S.; Arnold, P. L. Chem. Soc. Rev. 2007, 36, 1732. (g) Albrecht, M. Chem. Commun. 2008, 3601. (h) Normand, A. T.; Cavell, K. J. Eur. J. Inorg. Chem. 2008, 2781. (i) Lee, H. M.; Lee, C.-C.; Cheng, P.-Y. Curr. Org. Chem. 2007, 11, 1491. (j) Pugh, D.; Danopoulos, A. A. Coord. Chem. Rev. 2007, 251, 610. (k) César, V.; Bellemin-Laponnaz, S.; Gade, L. H. Chem. Soc. Rev. 2004, 33, 619. (l) Gade, L. H.; Bellemin-Laponnaz, S. Coord. Chem. Rev. 2007, 251, 718. (m) Edwards, P. G.; Hahn, F. E. Dalton Trans. 2011, 40, 10278. (19) Cabeza, J. A.; da Silva, I.; del Rı ́o, I.; Sánchez-Vega, M. G. Dalton Trans. 2006, 3966. (20) Magill, A. M.; McGuinness, S. D.; Cavell, K. J.; Britovsek, G. J. P.; Gibson, V. C.; White, A. J. P.; Williams, D. J.; White, A. H.; Skelton, B. W. J. Organomet. Chem. 2001, 617−618, 546. (21) Huheey, J. E. Inorganic Chemistry, 3rd ed.; Harper & Row: New York, 1983; p 412. (22) For additional examples of intramolecular C−H and C−N bond activations in ruthenium NHC complexes, see: Bramananthan, N.; Mas-Marzá, E.; Fernández, F. E.; Ellul, C. E.; Mahon, M. F.; Whittlesey, M. K. Eur. J. Inorg. Chem. 2012, 2213 and references cited therein. (23) CrysAlisPro RED, version 1.171.34.36; Oxford Diffraction Ltd., Oxford, U.K., 2010. (24) Altomare., A.; Burla, M. C.; Camalli, M.; Cascarano, G.; Giacovazzo, C.; Guagliardi, A.; Moliterni, A. G. C.; Polidori, G.; Spagna, R. J. Appl. Crystallogr. 1999, 32, 115. (25) SHELXL: Sheldrick, G. M. Acta Crystallogr. 2008, A64, 112. (26) XHYDEX: Orpen, A. G. J. Chem. Soc., Dalton Trans. 1980, 2509. (27) WinGX, version 1.80.05 (2009): Farrugia, L. J. J. Appl. Crystallogr. 1999, 32, 837. (28) (a) Perdew, J. P. Phys. Rev. B 1986, 33, 8822. (b) Becke, A. D. J. Chem. Phys. 1993, 98, 5648. (29) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Montgomery, J. A., Jr.; Vreven, T.; Kudin, K. N.; Burant, J. C.; Millam, J. M.; Iyengar, S. S.; Tomasi, J.; Barone, V.; Mennucci, B.; Cossi, M.; Scalmani, G.; Rega, N.; Petersson, G. A.; Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Klene, M.; Li, X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, E. R.; Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Ayala, P. Y.; Morokuma, K.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Zakrzewski, V. G.; Dapprich, S.; Daniels, A. D.; Strain, M. C.; Farkas, O.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.; Foresman, J. B.; Ortiz, J. V.; Cui, Q.; Baboul, A. G.; Clifford, S.; Cioslowski, J.; Stefanov, B. B.; Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi, I.; Martin, R. L.; Fox, D. J.; Keith, T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara, A.; Challacombe, M.; Gill, P. M. W.; Johnson, B.; Chen, W.; Wong, M.; Gonzalez, W. C.; Pople, J. A. GAUSSIAN-03 (Revision C2); Gaussian, Inc.: Wallingford, CT, 2004. (30) Hay, P. J.; Wadt, W. R. J. Chem. Phys. 1985, 82, 299.
ASSOCIATED CONTENT
S Supporting Information *
A table giving atomic coordinates for the DFT-optimized structure of compound 1 and CIF files giving crystallographic data for 2·0.5CH2Cl2 and 3. This material is available free of charge via the Internet at http://pubs.acs.org.
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AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. Notes
The authors declare no competing financial interest.
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ACKNOWLEDGMENTS This work has been supported by the Spanish MICINNFEDER grant CTQ2010-14933. REFERENCES
(1) For a recent review on NHC transition-metal cluster chemistry, see: Cabeza, J. A.; Garcı ́a-Á lvarez, P. Chem. Soc. Rev. 2011, 40, 5389. (2) Lappert, M. F.; Pye, P. L. J. Chem. Soc., Dalton Trans. 1977, 2172. (3) (a) Ellul, C. E.; Mahon, M. F.; Saker, O.; Whittlesey, M. K. Angew. Chem., Int. Ed. 2007, 46, 6343. (b) Critall, M. R.; Ellul, C. E.; Mahon, M. F.; Saker, O.; Whittlesey, M. K. Dalton Trans. 2008, 4209. (4) Ellul, C. E.; Saker, O.; Mahon, M. F.; Apperley, D. C.; Whittlesey, M. K. Organometallics 2008, 27, 100. (5) Bruce, M. I.; Cole, M. L.; Fung, R. S. C.; Forsyth, C. M.; Hilder, M.; Junk, P. C.; Konstas, K. Dalton Trans. 2008, 4118. (6) Zhang, C.; Luo, F.; Cheng, B.; Li, B.; Song, H.; Xu, S.; Wang, B. Dalton Trans. 2009, 7230. (7) Zhang, C.; Li, B.; Song, H.; Xu, S.; Wang, B. Organometallics 2011, 30, 3029. (8) Cabeza, J. A.; del Rı ́o, I.; Miguel, D.; Pérez-Carreño, E.; SánchezVega, M. G. Organometallics 2008, 27, 211. (9) (a) Cabeza, J. A.; del Rı ́o, I.; Miguel, D.; Sánchez-Vega, M. G. Chem. Commun. 2005, 3956. (b) Cabeza, J. A.; del Rı ́o, I.; Miguel, D.; Pérez-Carreño, E.; Sánchez-Vega, M. G. Dalton Trans. 2008, 1937. (10) Cabeza, J. A.; Van der Maelen, J. F.; Garcı ́a-Granda, S. Organometallics 2009, 28, 3666. (11) (a) Cabeza, J. A.; del Rı ́o, I.; Fernández-Colinas, J. M.; SánchezVega, M. G. Organometallics 2009, 28, 1243. (b) Cabeza, J. A.; del Rı ́o, I.; Miguel, D.; Sánchez-Vega, M. G. Angew. Chem., Int. Ed. 2008, 47, 1920. (12) (a) Cabeza, J. A.; del Rı ́o, I.; Pérez-Carreño, E.; Sánchez-Vega, M. G.; Vázquez-Garcı ́a, D. Angew. Chem., Int. Ed. 2009, 48, 555. (b) Cabeza, J. A.; del Rı ́o, I.; Pérez-Carreño, E.; Sánchez-Vega, M. G.; Vázquez-Garcı ́a, D. Organometallics 2010, 29, 4464. (13) Cabeza, J. A.; del Rı ́o, I.; Pérez-Carreño, E.; Pruneda, V. Organometallics 2011, 30, 1148. (14) Cabeza, J. A.; Damonte, M.; Garcı ́a-Á lvarez, P. Organometallics 2011, 30, 2371. (15) (a) Cabeza, J. A.; Damonte, M.; Garcı ́a-Á lvarez, P.; Kennedy, A. R.; Pérez-Carreño, E. Organometallics 2011, 30, 826. (b) Cabeza, J. A.; Damonte, M.; Garcı ́a-Á lvarez, P.; Hernández-Cruz, M. G.; Kennedy, A. R. Organometallics 2012, 31, 327. (16) (a) Cabeza, J. A.; del Rı ́o, I.; Fernández-Colinas, J. M.; PérezCarreño, E.; Sánchez-Vega, M. G.; Vázquez-Garcı ́a, D. Organometallics 2009, 28, 1832. (b) Cabeza, J. A.; Damonte, M.; Hernández-Cruz, M. G. J. Organomet. Chem. 2012, 711, 68. (17) Cooke, C. E.; Jennings, M. C.; Katz, M. J.; Pomeroy, R. K.; Clyburne, J. A. C. Organometallics 2008, 27, 5777. (18) For reviews on bi-, tri-, or polydentate ligands containing at least one NHC moiety, see: (a) Peris, E.; Crabtree, R. H. Coord. Chem. Rev. 2004, 248, 2239. (b) Mata, J. A.; Poyatos, M.; Peris, E. Coord. Chem. Rev. 2007, 251, 841. (c) Corberán, R.; Mas-Marzá, E.; Peris, E. Eur. J. Inorg. Chem. 2009, 1700. (d) Poyatos, M.; Mata, J. A.; Peris, E. Chem. 8359
dx.doi.org/10.1021/om3009298 | Organometallics 2012, 31, 8355−8359
