Octahedral Alkynylphosphine Ruthenium(II) Complexes: Synthesis

ARTICLE pubs.acs.org/Organometallics

Octahedral Alkynylphosphine Ruthenium(II) Complexes: Synthesis, Structure, and Electrochemistry Jes
us Berenguer, María Bernechea, Julio Fern
andez, Bel
en Gil, Elena Lalinde,* M. Teresa Moreno, Santiago Ruiz, and Sergio S
anchez Departamento de Química
Grupo de Síntesis Química de La Rioja, UA-CSIC, Universidad de La Rioja, 26006, Logro~no, Spain

bS Supporting Information ABSTRACT: Reaction of [RuCl2(PPh3)3] with excess of PPh2Ct CFc (Fc = ferrocenyl) proceeds with formation of [trans-RuCl2(PPh2CtCFc)4] (3), which reacts with HCtCR (R = Ph, Tol) via dissociative loss of one PPh2CtCFc ligand to yield vinylidene complexes [mer,cis-RuCl2(CdCHR)(PPh2CtCFc)3] (R = Ph 4a, Tol 4b). Reported herein also is the preparation of a series of trans/cis bis(alkynyl)tetrakis(alkynylphosphine) derivatives [Ru(CtCR0 )2(PPh2CtCR)4] (R0 = Ph, Tol; R = Ph, trans/cis-5a, 5b; R = Tol, trans/cis-6a, 6b; R = Fc, trans/cis-7a, 7b), synthesized by reaction of [trans-RuCl2(PPh2CtCR)4] (R = Ph 1, Tol 2, Fc 3) with an excess of HCtCR0 (R0 = Ph, Tol) and NEt3, in the presence or absence of NaPF6. In the preparation of cis-5a, the ketovinyl derivative [mer-Ru{kC,O-C(CH2COCH3)dCHPh}Cl(PPh2CtCPh)3] (8) was obtained as a byproduct in the presence of acetone. The solid-state structures of complexes 3, trans-5a, trans7a, and 8 have been determined by X-ray diffraction studies, showing the presence of several types of weak intramolecular hydrogen interactions. The cyclic voltammetry data for the mononuclear complexes (1, 2, trans/cis-5/6, and 8) show a quasi reversible oxidation attributed to the RuII/III couple and reveal a marked influence of the ligands and the geometry on the E1/2 values. The electrochemical behavior of the ferrocenylethynyldiphenylphosphine compounds 3, 4, and trans/cis-7 is more complex. Spectroelectrochemical comparative studies of related complexes (trans-7b vs trans-5b; 4 vs [RuCl2(CdCHTol)(PPh2CtCPh)3]) suggest that the first oxidation occurs at the ferrocene site of the PPh2CtCFc ligand.

’ INTRODUCTION The chemistry of metal
alkynyl complexes is of great interest because of their rich structural diversity and reactivity and also potential applications in material science.1,2 In particular, the linear geometry, rigidity, and possible π-electron conjugation have made metal alkynyl systems interesting candidates for active species of molecular and optoelectronic devices.3 In this area, ruthenium
alkynyl complexes have attracted significant attention because of their potential applications in optical materials, including nonlinear optics4,5 and more recently nanoparticles stabilized by Ru
CtC bonds,6 colorometric7 and fluorescent8 sensors, and the development of conducting materials.9
13 On the other hand, interest in the chemistry of alkynyl phosphines PPh2CtCR continues to grow,14 particularly due to their versatility as polyfunctional ligands and interesting reactivity involving P
C bond cleavages, insertion, and/or coupling processes.15 A special class of alkynylphosphines is the ferrocenylethynyldiphenylphosphine, PPh2CtCFc, which can act as a redox label and electron reservoir, providing access to systems having interesting optical and/ or electrochemical properties.16
19 A few years ago our group reported the synthesis of several six-coordinated Ru(II) complexes [trans-RuCl2(PPh2CtC
C6H4X)4] (X = H 1, Me 2, OMe, CF3) by simple reaction of RuCl3 3 xH2O with PPh2CtCR.20 Probably due to the steric demand of the alkynylphosphine ligand, these r 2011 American Chemical Society

complexes undergo a facile PPh2CtCR substitution by PhCt CH, leading to vinylidene complexes [mer,cis-RuCl2(CdCHPh)(PPh2CtCR)3] with concomitant reorganization of the geometry, and were found to show high efficiencies as precatalysts in the ringopening metathesis polymerization of norbornene. As part of a research program targeting the preparation and study of the electrochemical properties of complexes bearing ferrocenylalkynylphosphine and/or ferrocenylacetylide ligands,16,21 we became interested in the preparation of the related [transRuCl2(PPh2CtCFc)4] (3; Fc = ferrocenyl). As it is well-known, ferrocenyl and CtCFc groups have been extensively employed as the basis for multicomponent species to investigate the cooperation between metals and/or other redox-active centers.19,21,22 In particular, ruthenium complexes featuring ferrocenylethynyl fragments have allowed access to interesting mixed-valence species in which the molecular configuration and environment play a key role in the final electrochemical characteristics.9,23 In this paper we wish to report the synthesis, structural characterization, and redox behavior of complex [trans-RuCl2(PPh2CtCFc)4], 3. We also describe the preparation, characterization, and electrochemical properties of the vinylidene Received: June 16, 2011 Published: August 22, 2011 4665

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Scheme 1

complexes [mer,cis-RuCl2(CdCHR)(PPh2CtCFc)3] (R = Ph 4a, Tol 4b) and a series of trans and cis six-coordinated bis(alkynyl) tetrakis(alkynylphosphine) isomers [Ru(CtCR0 )2(PPh2CtCR)4] (R = Ph, Tol, Fc; R0 = Ph, Tol) (5
7). Furthermore, the new ketovinyl complex [mer-Ru{kC,O-C(CH2COCH3)dCHPh}Cl(PPh2CtCPh)3], 8, generated by C
H activation of one molecule of acetone through its formal addition to the CtC triple bond of a Ru
CtCPh group, is also reported.

’ RESULTS AND DISCUSSION Synthesis and Characterization. As noted in the Introduction, in spite of the steric demand of the alkynylphosphine, complexes of type [trans-RuCl2(PPh2CtCR)4] are easily formed by reaction of RuCl3 3 xH2O with adequate PPh2CtCR ligand in refluxing (∼1 h) ethanol. However, all attempts to prepare the related complex containing the ferrocenylethynyldiphenylphosphine, PPh2CtCFc, by this route were unsuccessful. The ruthenium complex of interest, [trans-RuCl2(PPh2CtCFc)4], 3, was successfully prepared from the starting complex [RuCl2(PPh3)3] by reaction with 4.5 equiv of PPh2CtCFc in CH2Cl2 (Scheme 1). Interestingly, the displacement of PPh3 in the precursor takes place under very mild conditions within minutes (1
3 min) and, alternatively, complexes [transRuCl2(PPh2CtCR)4] (R = Ph 1, Tol 2) employed in this work, are also obtained by this synthetic procedure in very high yield (∼90%). The fast displacement of the PPh3 ligand seems to be favored by the better electron donor nature of the alkynylphosphine ligands caused by the presence of the CtCR unit. We note that [RuCl2(PPh3)3] has been previously used as a precursor for the synthesis of complexes of the type [RuL4Cl2] [L = 1,3,5-triaza-7-phosphaadamantane (PTA), N-heterocyclic carbene (NHC), dppm, dppe, PPh2(CH2)4 PPh2 (ampy), PMe3].24,25 The reaction between [RuCl2(PPh3)3] and PPh2CtCR is clean, and only the trans-configured sixcoordinated complexes (1
3) are formed (singlet resonance, δ
3.97 to
5.04) even when the reactions are carried out in a molar ratio of 1:3. The new [trans-RuCl2(PPh2CtCFc)4], 3 was fully characterized by the usual spectroscopic methods (see Experimental Section) and by an X-ray diffraction study. X-ray quality crystals of this complex were grown by slow diffusion at
30 °C of n-hexane into a solution of the crude in CH2Cl2. Its molecular structure is shown in Figure 1, and the selected distances and angles are collected in Table 1. As expected, the ruthenium center presents a distorted octahedral coordination mode with the chlorine atoms occupying two mutually trans positions. The structural details are similar to those seen for 1 and in the range observed for other ruthenium
chloro derivatives.25,26 In particular, the Ru
P distance [2.3975(9) Å] is slightly shorter than that found in 1 [2.4077(8) Å],20 but longer than those

Figure 1. (a) View of the molecular structure of [trans-RuCl2(PPh2Ct CFc)4], 3. (b) View of the close C
H 3 3 3 Cl and C
H 3 3 3 CtC intramolecular contacts in 3.

reported in other [RuCl2L4] complexes [L = PPhH2 2.318(3), 2.319(3);26 PTA 2.316
2.353 Å],25 indicative of weaker P
Ru bonds probably due to the more sterically demanding alkynylphosphine ligands. Owing to the symmetry, the four phosphorus atoms and the Ru center lie in the same plane and the mutually trans CtCFc fragments are located above and below of this plane, forming a tetrahedral disposition around the ruthenium(II) center. As is shown in Figure 1b, the disposition of the trans-PPh2CtCFc ligands allows the existence of cooperative close intramolecular contacts (four Hendo) between the ortho phenyl proton groups with both the chlorine atoms and the free CtC alkynyl (four Hexo) as acceptor fragments. The observed C
H 3 3 3 Cl [2.5866(1), 2.6005(2) Å] and C
H 3 3 3 CtC [2.466(4)
2.819(4) Å] distances are shorter than the sum of the corresponding van der Waals radii of the involved atoms (rH + rCl = 1.20 + 1.75 = 2.95 Å; rCsp + rH = 1.78 + 1.20 = 2.98 Å) and within the range reported in other related systems.20 The IR spectrum of 3 shows two ν(CtC) strong bands (2180, 2161 cm
1) in the typical range of P-coordinated PPh2CtCR 4666

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Table 1. Selected Distances (Å) and Angles (deg) for Complexes 3, trans-5a, and trans-7a 3 2CHCl3 3 2hexane [trans-RuCl2(PPh2CtCFc)4], 3 Ru(1)
P(1)

2.3975(9)

Ru(1)
Cl(2)

2.4209(13)

P(1)
C(1) C(2)
C(3)

1.775(5) 1.429(6)

C(1)
C(2) H(14)
Cl(1)

1.183(6) 2.5866(1)

H(20)
Cl(1)

2.6005(2)

H(18)
C(1)

2.466(4)

H(24)
C(1)

2.535(4)

H(18)
C(2)

2.742(5)

H(24)
C(2)

2.819(4)

P(1)
Ru(1)
P(1)0

90.057(2)

P(1)
Ru(1)
P(1)00

176.39(6)

P(1)
Ru(1)
Cl(1)

91.80(3)

P(1)
Ru(1)
Cl(1)0

88.20(3)

Cl(1)
Ru(1)
Cl(1)0

180.0

P(1)
C(1)
C(2)

174.3(4)

C(1)
C(2)
C(3)

177.2(5)

[trans-Ru(CtCPh)2(PPh2CtCPh)4], trans-5a Ru(1)
P(1)

2.3843(4)

P(1)
C(7)

1.758(3)

C(7)
C(8)

1.188(3)

C(8)
C(9)

1.450(3)

Ru(1)
C(1)

2.062(2)

C(1)
C(2)

1.218(3)

C(2)
C(3)

1.442(3)

C(1)
Ru(1)
P(1)

87.781(17)

P(1)
Ru(1)
P(1)0

175.56(3)

P(1)
C(7)
C(8)

177.9(2)

C(7)
C(8)
C(9)

177.3(3)

Ru(1)
C(1)
C(2)

180.0

C(1)
C(2)
C(3)

180.0

[trans-Ru(CtCPh)2(PPh2CtCFc)4] 3 2CHCl3 3 2hexane, transRu(1)
P(1)

7a 3 2CHCl3 3 2hexane 2.3724(14) Ru(1)
C(1)

P(1)
C(7)

1.753(7)

C(1)
C(2)

1.103(16)

C(7)
C(8)

1.195(10)

C(2)
C(3)

1.452(17)

2.132(12)

C(8)
C(9)

1.433(10)

C(1)
Ru(1)
P(1)

92.06(5)

P(1)
Ru(1)
P(1)0

175.88(10)

P(1)
C(7)
C(8) Ru(1)
C(1)
C(2)

177.7(6) 180.0

C(7)
C(8)
C(9) C(1)
C(2)
C(3)

178.1(7) 180.0

ligands. The shift to higher wavenumbers in relation to free PPh2CtCFc (2146 cm
1) is comparable to those found in complexes 1 (24 cm
1) and 2 (27 cm
1). As we previously noted for 1 and 2, the characterization of 3 in solution is made at low temperature due to the low stability of these complexes in solution and the occurrence of a dissociative equilibrium with free alkynylphosphine. As can be seen in Figure S1a, the room-temperature 31P{1H} NMR spectrum of complex 3 exhibits the expected singlet resonance at δ
3.97, together with an additional signal at
32.9 ppm due to free PPh2CtCFc in a molar ratio 3:4, indicating a higher dissociation (∼20
25%) than that previously observed for complexes 1 and 2 (∼5
10%). Upon lowering the temperature, the free alkynylphosphine signal almost disappears, shifting the equilibrium toward complex 3. The complex exhibits a relatively rigid structure in solution, as confirmed by the low-temperature proton spectrum (Figure S1b), which displays separated signals for the ortho (δ 9.11 and 6.56) and meta (δ 7.02 and 6.79) protons of the phenyl groups, indicating hindered rotation around the P
C(Ph) bond, probably favored by the presence of the secondary contacts between the ortho-phenyl proton with the chlorine and CtC fragments, as confirmed by X-ray diffraction. Probably due to the higher dissociation of the phosphine ligand observed in this derivative, the reaction of 3 with an excess of alkyne ligand in CH2Cl2 is faster than that previously reported for 1 and 2.20 Thus, the reaction of 3 with (HCtCR; R = Ph,

Tol) is completed within minutes (15 min), giving rise to the formation of [mer,cis-RuCl2(CdCHR)(PPh2CtCFc)3] (R = Ph 4a, Tol 4b), contrasting with the previously reported 15 h necessary for completion of the reaction starting from 1 and 2.20 Both complexes show the expected triplet (δ 2.64 4a, 2.94 4b) and doublet (δ
0.36 4a,
0.16 4b) signals in their 31P{1H} NMR spectra, thus confirming the same geometry observed in the previously reported vinylidene complexes. Distinctive features are also the ν(CdC) band of the vinylidene ligand (1622 4a, 1632 cm
1 4b) together with those ν(CtC) of the PPh2CtCFc group (2182, 2157 4a, 2182, 2157 cm
1 4b) in their IR spectra, the dCHPh resonance, which appears as a multiplet at δ 5.15 in their 1H NMR spectra, and a characteristic low-field resonance at δ 359.6 (q, 2JC
P ≈ 35 Hz, 4a) and 360.0 (4b) attributed to the Rcarbon of the vinylidene unit in their 13C{1H} NMR spectra. Unfortunately, all attempts to obtain related ferrocenylvinylidene complexes were fruitless. For complexes 1 and 2, no reaction was detected with HCtCFc before decomposition of the precursors. In the case of complex [trans-RuCl2(PPh2CtCFc)4] (3), the reaction with HCtCFc evolves with initial formation of the expected [mer,cisRuCl2(CdCHFc)(PPh2CtCFc)3] complex, as observed by NMR spectroscopy [31P{1H}: δ 2.08 (t), 1.32 (d) (2JP
P = 27.5 Hz); 1 H: δ ∼5.50 (CdCH)]. However, due to its rapid decomposition in solution, it could not be isolated as a pure product. Alkynes are known to react with ruthenium complexes in the presence of a base to generate alkynyl complexes.2,7,8,13,27 By starting with halide derivatives, the addition of a suitable halide scavenger has been also reported.10,28,29 Therefore, we examined the possibility of formation of mixed alkynyl
alkynylphosphine ruthenium complexes by reactions of the dichloride derivatives 1
3 with terminal alkynes (HCtCR0 ; R0 = Ph, Tol, Fc) and NEt3 as a base and, in the presence or absence of NaPF6 as an abstractor of Cl
. As illustrated in Scheme 2, bis(alkynyl)tetrakis(alkynylphosphine)ruthenium complexes are synthesized by reaction of 1
3 with an excess of the alkyne (HCtCR0 ; R0 = Ph, Tol) in the presence of NEt3 as a deprotonating agent. Interestingly, we found that the final geometry depends on the presence or absence of NaPF6 to favor the abstraction of the chloride ligands. Thus, when the reactions are carried out in the simultaneous presence of NEt3 and NaPF6 in dichloromethane, they evolve with substitution of both chlorine atoms and formation of the trans-configured complexes [trans-Ru(CtCR0 )2(PPh2CtCR)4] (trans-5
7) as final complexes, which are isolated in moderate yields (33
54%) as pale yellow (5, 6) or orange (7) solids after workup. Monitoring some of the reactions by 31P{1H} NMR spectroscopy showed that the formation of the trans-configured complexes is relatively slow and clearly takes place through the initial formation of the cis isomers, which are concomitantly seen in the reaction mixture. For instance, after 90 min of stirring the reaction mixture 1/ HCtCPh/NEt3/NaPF6 reveals the presence of 1, trans-5a, and cis-5a in a molar ratio of ca. 1.5:2:6 together with free phosphine and OPPh2CtCPh, which are also present in small amounts. The precursor is consumed in ∼4 h, and the complexes cis-5a and trans-5a are still present at ca. ∼6:4. After 8 h, the trans-5a isomer was shown to be the main product of the reaction. When the reactions are carried out in the absence of NaPF6, the formation of the trans isomers is not detected. Under these conditions (Scheme 2) the reactions are faster and evolve mainly with formation of the cis-configured complexes, which are also isolated as beige (cis-5, cis-6) or orange (cis-7) solids in moderate yields (25
57%) by concentration to ca. 2 mL and addition of diethyl 4667

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Scheme 2

Figure 2. View of the molecular structure of (a) [trans-Ru(CtCPh)2(PPh2CtCPh)4] (trans-5a) and (b) [trans-Ru(CtCPh)2(PPh2CtCFc)4] (trans-7a).

ether. To our surprise, in the synthesis of complex cis-5a we systematically observed the formation of an unusual ketovinyl derivative complex [mer-Ru{kC,O-C(CH2COCH3)dCHPh}Cl(PPh2Ct CPh)3] (8) by modifying the workup of the final reaction mixture (see below and eq 1). Despite our efforts, the reactions of [trans-RuCl2(PPh2CtCR)4] 1
3 with ferrocenylacetylene evolve with formation of mixtures from which we were not able to isolate a pure product.

Complexes 5
7 are air stable solids and have been characterized by usual analytical and spectroscopic techniques (see Experimental Section for details). Their IR spectra show the expected ν(CtC) bands (2163
2185 cm
1, trans; 2161
2182 cm
1, cis) for the alkynylphosphine ligands and the CtCR moieties (2063
2065 cm
1, trans; 2072
2080 cm
1, cis). The trans geometry of trans-5
7 is in

accordance with the presence in their 31P{1H} NMR spectra of a single and slightly downfield singlet resonance in relation to the precursors (δ 3.99
5.90). However, the cis-configured complexes cis-5
7 display two triplets in the range δ 2.62
3.17;
4.10 to
2.55 with the expected characteristic mutually cis (2JP
P ≈ 37 Hz) coupling constant. The low solubility of the complexes hampered the acquisition of the 13C{1H} NMR spectra, and only for complexes trans-5a and trans-6a could acetylenic carbon resonances be observed after prolonged accumulation (see Experimental Section). It is worth noting that complexes trans/cis-5/6 are more stable in solution than their precursors (1 and 2) and only show partial decomposition after a week in CDCl3 solution, while complexes with the ferrocenylalkynylphosphine ligand (trans/cis-7) decompose in solution in hours. Single crystals suitable for X-ray crystallography were obtained for complexes [trans-Ru(CtCPh)2(PPh2CtCR)4] (R = Ph trans-5a, Fc trans-7a). The molecular structures are shown in Figure 2, and selected distances and angles for both complexes are collected in Table 1. As expected, the ruthenium center presents in both structures a distorted octahedral coordination mode with the alkynyl groups occupying two mutually trans positions. Complexes trans-5a and trans-7a crystallize in the P-4/21/c and I-4 groups respectively, the ruthenium, CR, Cβ, and Cγ atoms being in a quaternary 4668

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Figure 3. Variable-temperature 1H NMR spectra (400 MHz) in CDCl3 in the aromatic region of [trans-Ru(CtCPh)2(PPh2CtCPh)4] (trans-5a) (∼1  10
3 M).

axis. Therefore, the alkynyl fragments in both structures are totally linear (Ru
CR
Cβ and CR
Cβ
Cγ 180°). The structural details are in the range of what is usually observed for neutral bis(alkynyl)phosphine complexes [RuP4(CtCR)2].30 Note that the Ru
P distances are slightly shorter than those found in their precursors [2.3843(4) Å trans-5a, 2.4077(8) Å 1; 2.3724(14) Å trans-7a, 2.3975(9) Å 3]. As shown in Figure S2, short contacts between the ortho protons of the PPh2 entities and the alkynyl carbons of both alkynylphosphines and alkynyl ligands are seen (2.467
2.583 Å). These contacts are in the range found in other complexes with C
H 3 3 3 (CtC) interactions.20,31 Variable-temperature 1H NMR spectra recorded for two complexes (trans-5a and trans-6a), as illustrative examples, revealed that these weak interactions are maintained at low temperature. As shown in Figure 3 for [trans-Ru(CtCPh)2(PPh2CtCPh)4], trans-5a, two different signals are seen at low temperature for the endo and exo protons in the ortho and meta positions of the phenyl groups due to the PPh2 units. This pattern indicates that the interactions of these protons with the alkynyl fragments hinder the rotation of the Ph rings around the P
C bonds on the NMR time scale. Upon increasing the temperature, the ortho proton signals clearly broaden, the coalescence temperature being 263 K, and a broad single signal is still seen at 313 K. The energetic barrier calculated for this process is similar in both complexes (ΔGq263 ≈ 47.2 kJ/mol trans-5a, ΔGq263 ≈ 46.6 kJ/mol trans-6a) and also comparable to the observed in [trans-RuCl2(PPh2Ct CPh)4], 1 (ΔGq263 ≈ 46.5 kJ/mol).20 Although photoisomerization of octahedral complexes and the thermally reversible nature of this process have been previously reported in other Ru(II) complexes,32,33 all the attempts to isomerize one of the cis derivatives (once isolated as pure complexes) to the trans failed, either by heating or ultraviolet irradiation. As followed by 31P{1H} NMR spectroscopy, the only phosphorus-containing product formed in all attempts was oxidized alkynylphosphine. In order to gain some insight into this process, DFT calculations (Gaussian03, B3LYP/LanL2Dz) were performed on trans/cis isomer complexes [Ru(CtCPh)2(PPh2CtCPh)4] trans-5a and

cis-5a (see Supporting Information: Tables S1
S4 and Figures S11, S12). The calculated geometry of the trans isomer compares well with that observed in the X-ray studies for trans-5a (see Table S3), the bigger difference being the longer Ru
P distances found. DFT calculations show that the trans isomer is ∼75.6 kJ mol
1 more stable than the cis isomer. This result contrasts with the reported calculations performed on cis/trans [Ru(CtCMe)2(PMe3)4],33 in which the difference between the isomers is only 7.6 kJ mol
1. Formation of [mer-Ru{kC,O-C(CH2COCH3)dCHPh}Cl(PPh2CtCPh)3] (8). As commented before, the formation of this derivative was observed as a secondary product in the synthesis of cis5a. After filtration of the cis derivative cis-5a, treatment of the filtrate (see Experimental Section) with acetone gives rise to a solution from which the pale yellow complex 8 crystallized in small yield (17%). The structure of the complex was determined (Figure 4) by a singlecrystal X-ray diffraction study, which confirmed the presence of a chloride ligand and the formation of a ketovinyl group, C(CH2COCH3)dCHPh, acting as a k2C,O chelate ligand. The formation of 8 was unexpected because it involves not only activation of a C
H bond of a CH3COCH3 molecule but also its formal addition to a CtC triple bond. Activation of acetone in basic media yielding ketovinyl derivatives has many precedents.34 In ruthenium chemistry the activation of acetone by a hydroxo bridging complex to give a ketovinyl bridging derivative has been reported.35 Endo vinyl ketones having also a five-membered ring have been generated by a combination of insertion and hydratation processes of [Tp(NHdCPh2)(PPh3)Ru-Cl] with HCtCPh in the presence of H2O.36 In the case of complex 8, the mechanism of its formation is unclear, and it was not depply investigated. We observed that performing the reaction of 1 with HCtCPh and NEt3 in a mixture of CH2Cl2/acetone, complex 8 was also generated as a byproduct, but its yield was similar, being the main product cis-5a. We also note that the attempts to obtain complex 8 by treatment of the previously reported [mer,cisRuCl2(CdCHPh)(PPh2CtCPh)3]20 complex with acetone in the presence of base (NEt3, KOH, etc.) were fruitless, thus excluding the 4669

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Table 3. Electrochemical Data for Complexes 1
8 and the Free Ligands HCtCFc and PPh2CtCFca E1/2 (V) CH2Cl2 Fc/Fc+ HCtCFc/HCtCFc+ PPh2CtCFc/PPh2CtCFc+ [trans-RuCl2(PPh2CtCPh)4], 1 [trans-RuCl2(PPh2CtCTol)4], 2 [trans-RuCl2(PPh2CtCFc)4], 3 [mer,cis-RuCl2(dCdCHPh)(PPh2CtCFc)3], 4a [mer,cis-RuCl2(dCdCHTol)(PPh2CtCFc)3], 4b [trans-Ru(CtCPh)2(PPh2CtCPh)4], trans-5a [trans-Ru(CtCTol)2(PPh2CtCPh)4], trans-5b [trans-Ru(CtCPh)2(PPh2CtCTol)4], trans-6a [trans-Ru(CtCTol)2(PPh2CtCTol)4], trans-6b [trans-Ru(CtCPh)2(PPh2CtCFc)4], trans-7a [trans-Ru(CtCTol)2(PPh2CtCFc)4], trans-7b [cis-Ru(CtCPh)2(PPh2CtCPh)4], cis-5a [cis-Ru(CtCTol)2(PPh2CtCPh)4], cis-5b [cis-Ru(CtCPh)2(PPh2CtCTol)4], cis-6a [cis-Ru(CtCTol)2(PPh2CtCTol)4], cis-6b [cis-Ru(CtCPh)2(PPh2CtCFc)4], cis-7a [cis-Ru(CtCTol)2(PPh2CtCFc)4], cis-7b [mer-Ru{kC,O-C(CH2COCH3)d CHPh}Cl(PPh2CtCPh)3], 8

Figure 4. Molecular structure of [mer-Ru{kC,O-C(CH2COCH3)dCHPh}Cl(PPh2CtCPh)3] (8).

Table 2. Selected Distances (Å) and Angles (deg) for Complex 8 3 0.5(CH3COCH3) [mer-Ru{kC,O-C(CH2COCH3)dCHPh}Cl(PPh2CtCPh)3], 8 3 0.5(CH3COCH3) Ru(1)
P(1) 2.3698(7) Ru(1)
P(2) 2.3490(7) Ru(1)
P(3) 2.3458(7) Ru(1)
C(4) 2.069(3) Ru(1)
O(1) 2.129(2) Ru(1)
Cl(1) 2.4116(7) C(2)
O(1) 1.243(4) C(2)
C(3) 1.295(4) C(3)
C(4) 1.445(4) C(4)
C(5) 1.317(4) C(1)
C(2) 1.494(5) C(5)
C(6) 1.472(4) C(12)
C(13) 1.192(4) C(32)
C(33) 1.212(4) C(52)
C(53) 1.202(4) P(1)
C(12) 1.756(3) P(2)
C(32) 1.752(3) P(3)
C(52) 1.757(3) O(1)
Ru(1)
Cl(1) 171.17(6) O(1)
Ru(1)
P(1) 95.07(6) O(1)
Ru(1)
P(2) 90.79(6) O(1)
Ru(1)
P(3) 90.09(6) P(1)
Ru(1)
C(4) 173.90(8) P(2)
Ru(1)
P(3) 171.16(2) P(1)
Ru(1)
P(2) 93.91(3) P(1)
Ru(1)
P(3) 94.78(3) P(1)
C(12)
C(13) 172.8(3) P(2)
C(32)
C(33) 172.5(3) P(3)
C(52)
C(53) 174.3(3) C(12)
C(13)
C(14) 177.4(3) C(32)
C(33)
C(34) 177.0(3) C(52)
C(53)
C(54) 179.1(4) Ru(1)
C(4)
C(5) 78.48(10) Ru(1)
C(4)
C(3) 109.07(18) C(4)
C(5)
C(6) 132.4(3) C(4)
C(3)
C(2) 116.6(2) C(3)
C(2)
O(1) 124.8(3) C(3)
C(2)
C(1) 115.5(3) Ru(1)
O(1)
C(2) 110.6(2)

formation of this vinylidene derivative as an intermediate in the mechanism leading to 8. The X-ray diffraction analysis (Figure 4, Table 2 for selected bond distances and angles) reveals a distorted octahedral geometry around the ruthenium center with a mer disposition of the alkynylphosphine ligands and the chloride in trans position to the oxygen atom of the formed chelate. The five-membered oxoruthenium cycle is planar (torsion angle between 1.16° and 2.83°) with the phenyl ring of the exo double bond slightly twisted (∼30.5°) and in a trans disposition to the ruthenium center. The Ru(1)
C(4) [2.069(3) Å] and Ru(1)
O(1) [2.129(2) Å] bond distances are comparable to those observed for other Ru
C(vinyl) and Ru
O (ketone, acetate) complexes.37 In the ligand, the exo CdC double [C(4)
C(5) 1.317(4) Å] and single C(3)
C(4) [1.445(4) Å] bonds within the cycle are unremarkable, but the C(2)
C(3) distance [1.295(4) Å] is clearly shorter than expected for a single bond. All the Ru
P lengths are

0.46 0.61 0.61 0.69 0.67 0.66, 0.91 0.70, 1.13 0.68, 1.02 0.64 0.55 0.60 0.52 0.61, 0.71, 0.90 0.45, 0.71, 0.84 0.65 0.61 0.64 0.57 0.60,b 0.69, 0.93b 0.57,b 0.71, 0.91b 0.56

a All measurements were carried out at 25 °C with 0.1 M NBu4PF6. Scan rate 100 mV s
1 and vs Ag/AgCl reference electrode. b Ep.

smaller than that found in its precursor, probably due to the loss of one steric-demanding alkynylphosphine ligand. As expected, the Ru
P(1) distance [2.3698(7) Å] is slightly longer than the remaining Ru
P distances [2.3490(7), 2.3458(7) Å], in accordance with the stronger trans influence exerted by the vinyl carbon atom relative to the phosphine ligands. Weak secondary Cl 3 3 3 H [2.7558(7)
2.8247(7) Å] and O 3 3 3 H [2.570 (2) Å] contacts with three or two ortho hydrogen atoms of the phenyl rings of the PPh2 groups are seen (see Figure S3). Also weak C
H 3 3 3 (CtC) contacts are found between two ortho protons of the PPh2 groups and the triple bond of each alkynylphosphine [2.5278(3)
2.640(3) Å]. The IR spectrum exhibits a strong broad band at 2172 cm
1 due to the ν(CtC) vibrations of the terminal alkynylphosphine ligands and two additional strong bands at 1621 and 1592 cm
1, which are attributable to the ν(CdC) and ν(CdO) vibrations of the chelating C(CH2COCH3)dCHPh. In spite of the asymmetry of the complex, the room-temperature 31P{1H} NMR spectrum of 8 shows a singlet resonance (δ 13.2), suggesting the occurrence of a dynamic behavior that equilibrates the phosphine ligands probably associated with a possible hemilabile behavior of the ketovinyl ligand. By lowering the temperature the signal broadens, coalesces (∼270 K), and finally splits at 240 K in two close, different resonances (AB2 system) located at 13.94 and 13.42 ppm with a coupling constant of 25 Hz, in agreement with the solid-state structure. In the 1H NMR spectrum, the characteristic vinyl proton of the ligand appears at 4.57 ppm and correlates with a doublet resonance (3JP
C ≈ 4.5 Hz) at 120.51 ppm in the 13C{1H} NMR spectrum, whereas the methyl proton is seen at 2.30 ppm. A signal at 1.26 (δ13C 45.87) is tentatively assigned to the methylenic CH2 group. Electrochemistry and Spectroelectrochemistry. The electrochemical properties of 1
8 were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in dichloromethane. All electrochemical data are collected in Table 3, and some of the voltammograms are depicted in Figure 5 and in the Supporting Information (Figures S4
S7). The trans/cis complexes 5 and 6 show a unique wave on sweeping at anodic potential, which is attributed to 4670

dx.doi.org/10.1021/om2005194 |Organometallics 2011, 30, 4665–4677

Organometallics

ARTICLE

Figure 5. Comparative CV of complexes 1 (black line), trans-5b (red line), and cis-5b (blue line) in CH2Cl2 at 25 °C at a scan rate of 100 mV s
1 (∼ 5  10
4 M).

the RuII/RuIII couple. In all these derivatives, the presence of the alkynyl ligands produces a cathodic shift of the potential compared to their dichloro precursors (e.g., [trans-RuCl2(PPh2CtCPh)4], 1, 0.69 V vs [trans-(CtCPh)2(PPh2CtCPh)4], trans-5a, 0.64 V), confirming that the alkynyl ligands act as better σ-donors than the chloro ligands. As expected, this effect is more pronounced in the tolylacetylide complexes, due to the higher electron-rich nature of the CtCTol group in relation to the CtCPh ligand (Figure 5). In addition, the E1/2 of the RuII/RuIII couple depends on the geometry, with the cis-configured complexes exhibiting higher E1/2 oxidation potential than the trans isomers, this effect being more pronounced in the tolylacetylide derivatives. The sensitivity of the redox response to the nature of the alkynyl substituent and also to the configuration cis or trans is consistent with the arylacetylide character of the HOMO in these complexes, as suggested by DFT calculations (see Table S4). This fact is in accordance with the non-innocent redox behavior previously shown by carbon-rich ligands in other metal complexes with unsaturated ligands,12,29,38 which suggests that the oxidation cannot be described as only metal-centered since the alkynyl ligands have an important role in the oxidation process. The substituent in the alkynylphosphine seems to also have a small influence, with slight cathodic shifts in complexes containing the more electron donating PPh2CtCTol ligand. The ketovinyl complex 8 shows a single wave at low potential (0.56 V), probably reflecting the donor effect of the oxometallacycle. The analysis of the ferrocenyl-containing derivatives 3, 4, and trans/cis-7 is much more complex, since they contain within each molecular entity two distinct electroactive sites, the ferrocenyl (Fc) groups and the ruthenium center, and it is not a priori obvious which one of the two MII/III couples is oxidized at lower potential. This oxidation would involve the formation of heterometallic mixed-valent intermediates Fc+/RuII or Fc/RuIII, which depends on the molecular configuration and environment.39 Furthermore, in the case of [trans-RuCl2(PPh2CtCFc)4], 3, the appearance of the signal of free alkynylphosphine in its 31 1 P{ H} NMR spectrum at 20 °C (vide supra) must be taken into account. As observed in Figures S4 and S5, the CV of complexes 3, 4a, and 4b show a similar pattern, with two reversible waves being observed in all the voltammograms. The first wave is tentatively assigned to the ferrocenyl groups of the PPh2CtCFc ligands, based on the bigger current observed for this wave and the results of the UV
vis
NIR spectroelectrochemistry studies (vide infra). The slight anodic shift for the Fc groups (50 3, 90 4a,

Figure 6. Spectroscopic changes upon gradual oxidation of (a) [transRu(CtCTol)2(PPh2CtCPh)4] (trans-5b) and (b) [trans-Ru(CtCTol)2(PPh2CtCFc)4] (trans-7b) in an OTTLE cell.

70 mV 4b) upon coordination of the PPh2CtCFc (see Table 3) has been previously observed in other [M-PPh2CtCFc] complexes.16 The second wave could be assigned to the RuII/RuIII couple or to the electrogenerated byproduct. We note that when the CV of complex 3 was carried out at lower temperatures, both waves were visible, but it was also observed some electrodeposition on the surface of the electrode (Figure S4). The voltammograms of the four ferrocenyl acetylide complexes 7 are more complicated (Figures S6 and S7), showing a predominant wave around 0.7 V in both the trans and cis isomers, together with small waves at lower (0.61
0.45 V) and higher potentials (0.91
0.84 V), which almost disappear in the second scan (Figure S7a). The study of the absorption spectra of the oxidized species should indicate which one of the MII/MIII couples is oxidized first in these complexes.39 Aiming to get more insight into the behavior of these complexes, we have carried out in situ spectroelectrochemical (SEC) measurements of the selected complexes: trans-configured tolylacetylide derivatives trans-5b and trans-7b and the vinylidene complexes 4a and 4b. Representative spectra obtained in the SEC experiments are depicted in Figure 6 (trans-5b and trans-7b) and in the Supporting Information (Figures S8
S10 for [mer,cis-RuCl2(CdCHTol)(PPh2CtCPh)3] and 4). All UV
vis
NIR spectra were registered in 0.1 M NBu4PF6 dichloromethane solutions in an optically transparent thin-layer electrolytic (OTTLE) cell. We noted that the optical spectra of several bis(alkynyl) cationic complexes [trans-Ru(Ct CR)2(L-L)2]+ (L-L = dppm,40 dppe5), generated in a similar way, have been reported. In these complexes, the observed low-energy band in the near-IR region [7520
9179 cm
1 (1330
1090 nm)] 4671

dx.doi.org/10.1021/om2005194 |Organometallics 2011, 30, 4665–4677

Organometallics has been assigned as LMCT,40 due to the promotion of an electron from an ethynyl p orbital to the partially occupied HOMO (RuIII + CtC).5 In the case of our complexes, the oxidation of [transRu(CtCTol)2(PPh2CtCPh)4], trans-5b, containing only the RuII as a redox-active center, and that of [trans-Ru(CtCTol)2(PPh2CtCFc)4], trans-7b (combining Fc and RuII centers), are clearly different. As can be seen in Figure 6, oxidation of trans-5b produces the gradual growth of a near-IR band (∼1100 nm), which exhibits a vibronic progress (Δν ≈ 2000 cm
1) consistent with the involvement of CtC fragments. In accordance with assignments in related bis(alkynyl)bis(diphenylphosphine) complexes,5 this band is ascribed as alkynyl-to-metal charge transfer in nature (LMCT) from the donor alkynyl CtCTol to the RuIII center. By contrast, oxidation of [trans-Ru(CtCTol)2(PPh2CtCFc)4], trans-7b, containing also tolylacetylide groups and ferrocenylethynylphosphine ligands, evolves with the appearance of a band around 720 nm. The absence of a band in the typical range of RuIII complexes [transRu(CtCR)2(diphosphine)2]+ suggests that in this complex the first oxidation is located on the ferrocenyl group of the alkynylphosphines. In fact, ferrocenium systems are known to exhibit a weak absorption band around 700 nm (λ = 698 nm for FcCtCH]+),41 assigned broadly to LMCT. In complex trans-7b, the lowest energy band observed in the oxidation is therefore tentatively ascribed to a LMCT centered on the coordinated PPh2CtCFc groups. These results compare well with those found for the ruthenium vinylidene complexes [mer,cis-RuCl2(CdCHTol)(PPh2Ct CPh)3] (only with the RuII as redox-active center) and [mer,cisRuCl2(CdCHR)(PPh2CtCFc)3] (R = Ph 4a, R = Ph 4b) (combining Fc and RuII centers). Thus, the oxidation of the mononuclear complex [mer,cis-RuCl2(CdCHTol)(PPh2CtCPh)3] produces the growth of a broad low-energy band located around 850 nm (Figure S8). Although the assignment of this near-IR band is not obvious, following previous works it could be tentatively attributed to a LF or LMCT transfer related to the RuIII center.39 By contrast, in the oxidation of 4a and 4b the lowest energy band observed is centered around 670 nm (Figures S9 and S10), suggesting again that the initial oxidation takes place on the ferrocene group.

’ CONCLUSIONS In summary, we report the successful synthesis of the new dichloride [trans-RuCl2(PPh2CtCFc)4] (3) and vinylidene [mer, cis-RuCl2(CdCHR)(PPh2CtCFc)3] (4a, 4b) ruthenium complexes containing the functionalized ferrocenylethynyldiphenylphosphine (PPh2CtCFc) ligand. Furthermore, the synthesis of a series of trans and cis isomers [Ru(CtCR0 )2(PPh2CtCR)4] (trans
cis5
7) has been achieved by reaction of [trans-RuCl2(PPh2Ct CR)4] (R = Ph 1, Tol 2, Fc 3) with alkynes and NEt3, in the presence or absence of NaPF6. No photoisomerization has been found between these isomers, contrasting with the easy photoisomerization observed in other [Ru(CtCR)2(PMe3)4] derivatives.33 In the synthesis of cis-5a, the unexpected ketovinyl derivative [merRu{kC,O-C(CH2COCH3)dCHPh}Cl(PPh2CtCPh)3] (8), generated by formal activation of a C
H bond in acetone, was also formed in small yield. The electrochemical behavior of all derivatives has been examined. The mononuclear complexes (1,2, trans/cis-5/6, and 8) show a single redox wave in the range 0.52
0.69 V, assigned to the RuII/III couple. As expected, replacement of chloride ligands in 1 and 2 by the electron-rich alkynyl groups causes a cathodic shift of the oxidation potential, which depends on the alkynyl substituent (CtCTol > CtCPh) and the geometry of the final complexes (trans-5,6 > cis-5,6). The behavior of the complexes containing

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PPh2CtCFc ligands (3, 4, and 7) is more complex. UV
vis
NIR spectroelectrochemical comparative studies of the in situ oxidized species (trans-7b vs trans-5b and 4 vs [RuCl2(CdCHTol)(PPh2CtCPh)3]) suggest that the first oxidation of these compounds occurs at the ferrocene site.

’ EXPERIMENTAL SECTION All reactions were carried out under Ar atmosphere using Schlenk tube techniques. Solvents were obtained from a solvent purification system (MBRAUN MB SPS-800). IR spectra were recorded on a FT-IR Nicolet Nexus spectrometer as Nujol mulls between polyethylene sheets, and NMR spectra were recorded on either a Bruker ARX 300 or a Bruker Avance 400 spectrometer. Chemical shifts are reported in ppm relative to external standards (SiMe4, CFCl3 and 85% H3PO4), and coupling constants in Hz. The low solubility of the cis derivatives 5
7 precludes their characterization by 13C{1H} NMR spectroscopy. Elemental analyses were carried out on a Perkin-Elmer 2400 CHNS/O microanalyzer, and MALDI-TOF spectra on a Microflex MALDI-TOF Bruker spectrometer, operating in the linear and reflector modes using dithranol as matrix. Cyclic voltammetry and pulse differential were carried out in 0.1 M NBu4PF6 solutions as supporting electrolyte, using a three-electrode configuration (Pt disk as working electrode, Pt-wire counter electrode, Ag/AgCl reference electrode) on a Voltalab PST 050. The ferrocene/ferrocenium couple served as internal reference (+0.46 V vs Ag/AgCl). UV
visible
near-IR spectra were recorded on a Shimadzu UV-3600 spectrometer in a home-built OTTLE cell (1 mm light pass length) using saturated solutions of the ruthenium complexes (due to their low solubility) and 0.1 M NBu4PF6. Starting materials [RuCl2(PPh3)3],42 PPh2CtCPh,43 PPh2CtCTol,43 and PPh2CtCFc17 were prepared as previously described.

Synthesis of [trans-RuCl2(PPh2C;CR)4] (R = Ph 1, Tol 2, Fc 3). A solution of [RuCl2(PPh3)3] was treated with a slight excess of the appropriate PPh2CtCR ligand in CH2Cl2 (20 mL), and the mixture stirred at room temperature for 3 min. The solution was concentrated in vacuo to ca. 5 mL, forming a beige (1, 2) or orange (3) precipitate, which was filtered and washed with EtOH and Et2O. Complexes 1 and 2 were obtained in 88% and 91% yields, respectively, by starting from 0.104 mmol (0.1 g) of [RuCl2(PPh3)3] and 0.468 mmol of PPh2CtCR (R = Ph, 0.135 g; R = Tol, 0.140 g). Spectroscopic characterization was consistent with that previously reported.20 A mixture of PPh2Ct CFc (0.655 g, 1.66 mmol) and [RuCl2(PPh3)3] (0.353 g, 0.369 mmol) afforded 0.420 g of 3 (65% yield). Data for [trans-RuCl2(PPh2CtCFc)4], 3. 1H NMR (δ, 300.1 MHz, CDCl3) at 223 K: 9.11 (s, br, o-H), 8.01 (m, m-H), 7.66 (m), 7.37 (m), 7.02 (m), 6.79 (m), 6.55 (m, o-H) (40H, aromatics), 4.74 (s, C5H4, 8H), 4.38 (s, 28H, C5H4, Cp); at 293 K: signals due to 3 and PPh2CtCFc are observed, ∼8.10 (br), 7.88 (m), 7.66 (m), 7.35 (m), 7.19 (m), 7.11 (m), 7.01 (m) 6.90 (m), 4.73 (s, Fc), 4.61 (s, Fc), 4.54 (s, Fc), 4.38 (s, Fc), 4.31 (s, Fc), 4.23 (s, Fc), 4.14 (s, Fc), 4.08 (s, Fc). 31P{1H} NMR (δ, 121.5 MHz, CDCl3) at 223 K:
4.9 (s); at 293 K:
3.97 (s) (a signal due to free PPh2CtCFc at
32.93 is also observed, ratio 3:PPh2CtCFc ≈ 3:4). IR (cm
1): ν(CtC) 2180, 2161(s). MALDI-TOF (+): m/z (%) 1493 [Ru(CtCFc)(PPh2CtCFc)3]+ (25), 1319 [RuCl(PPh2CtCFc)3]+ (33), 960 [RuCl2(PPh2CtCFc)2]+ (100), 925 [RuCl(PPh2CtCFc)2]+ (60). Anal. Calcd (%) for C96H76Cl2Fe4P4Ru: C, 65.93; H, 4.38. Found: C, 66.15; H, 4.43.

Synthesis of [mer,cis-RuCl2(CdCHR)(PPh2C;CFc)3] (R = Ph 4a, Tol 4b). To a solution of [trans-RuCl2(PPh2CtCFc)4] in CH2Cl2 (20 mL) was added 15 equiv of the acetylene (HCtCR) ligand. After 15 min stirring, the solution was concentrated in vacuo (∼2 mL), and addition of n-hexane (∼5 mL) produced the precipitation of 4. Data for [mer,cis-RuCl2(CdCHPh)(PPh2CtCFc)3], 4a. Starting from [trans-RuCl2(PPh2CtCFc)4] (0.07 g, 0.040 mmol), HCtCPh (65 μL, 0.60 mmol), 4a, was obtained as a pale orange solid (0.049 g, 84% yield). 4672

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Organometallics 1

H NMR (δ, 300.1 MHz, CDCl3, 298 K): 8.20 (s), 7.97 (t), 7.77 (s), 7.66 (s), 7.32 (m), 6.90 (m), 6.45 (s), (35H, aromatics), 5.15 (m, 1H, CdCHPh,), 4.50 (s, Fc), 4.38 (s, Fc), 4.23 (s, Fc), 4.09 (s, Fc). 13C{1H} NMR (δ, 100.64 MHz, CDCl3, 298 K): 359.6 (q, 2JP
C ≈ 35, CR, CRdCHPh), 134.3 (t, 2+4JP
C ≈ 11.2, o-C, trans-PPh2), 133.8 (d, 2JP
C ≈ 10.8, o-C, PPh2 trans to Cl), 133.1 (t, 2+4JP
C ≈ 9.3, o-C, trans-PPh2), 132.6 (m), 132.3 (s), 132.0 (s), 131.0 (s), 130.9 (s), 129.8 (s), 129.6 (s), 129.5 (s), 128.6 (pt), 128.4(s), 128.3 (s), 128.1 (s), 127.3 (pt, 3+5JP
C ≈ 11.0, m-C, trans-PPh2), 127.2 (d, 3JP
C ≈ 11.1, m-C, PPh2, trans to Cl), 126.8 (pt, 3 +5 JP
C ≈ 9, m-C, trans-PPh2), 126.4 (s), 124.6 (s), 110.9 (m, Cβ, PPh2CRt CβFc), 110.3 (m, Cβ, CdCβHPh), 108.6 (m, Cβ, PPh2CRtCβFc), 79.8 (m, 1JP
C ≈ 100, CR, PPh2CRtCβFc, trans to Cl), 79.0 (AXX0 Y, 1+3JP
C ≈ 87, CR, PPh2CRtCβFc, trans-PPh2), 72.5 (C5H4, Fc), 72.4 (C5H4, Fc), 72.1 (C5H4, Fc), 70.4 (C5H4, Fc),70.2 (C5H4, Fc), 69.9 (Cp, Fc), 69.7 (Cp, Fc), 69.6 (C5H4, Fc), 69.4 (C5H4, Fc), 64.0 (C5H4, Fc), 63.4 (C5H4, Fc). 31P{1H} NMR (δ, 121.5 MHz, CDCl3, 298 K): 2.64 (t),
0.36 (d) (2JP
P = 27.1). IR (cm
1): ν(CtC) 2181 (sh), 2157 (s), ν(CdCHPh) 1622 (m). MALDI-TOF (+): m/z (%) 1385 [Ru(CdCHPh)(PPh2Ct CFc)3]+ (8), 1319 [RuCl(PPh2CtCFc)3]+ (78), 1026 [RuCl(Ct CHPh)(PPh2CtCFc)2]+ (21), 991 [Ru(CdCHPh)(PPh2CtCFc)2]+ (100). Anal. Calcd (%) for C80H63Cl2Fe3P3Ru: C, 65.96; H, 4.36. Found: C, 66.53; H, 4.55. Data for [mer,cis-RuCl2(CdCHTol)(PPh2CtCFc)3] 4b. Starting from [trans-RuCl2(PPh2CtCFc)4] (0.08 g, 0.046 mmol), HCtCTol (87 μL, 0.686 mmol), 4b was obtained as an orange solid (0.052 g, 77% yield). 1H NMR (δ, 300.1 MHz, CDCl3, 298 K): 8.18 (s), 7.96 (m), 7.77 (s), 7.66 (s), 7.34 (s), 7.11 (s), 7.01 (s), 6.89 (m), 6.68 (s), 6.37 (s) (34H, aromatics), 5.15 (m, 1H, CdCHTol,), 4.53 (s, Fc), 4.49 (Fc), 4.39 (s, Fc), 4.30 (s, Fc), 4.24 (s, Fc), 4.17 (s, Fc), 4.10 (s, Fc), 2.26 (s, 3H, Tol). Carbon signals were systematically found somewhat broad at low temperature, and at rt the product decomposes. 13C NMR (δ, 100.64 MHz, CDCl3, 298 K): 360.0 (m, CR, CRdCHTol), 134.1
131.6 (m, aromatic), 130.7 (d), 129.5 (s), 129.3 (s), 128.8 (s), 128.4 (m), 127.3 (m), 127.0 (s), 126.9 (s), 126.8 (m), 126.0 (m), 125.8 (s), 110.1 (m, Cβ, CdCβHTol), 109.3 (m, Cβ, PPh2CRtCβFc, trans-PPh2), 107.7 (m, Cβ, PPh2CRtCβFc, trans to Cl), 80.4 (m, CR, PPh2CRtCβFc, trans to Cl), 79.1 (m, CR, PPh2CRtCβFc, trans-PPh2), 72.5 (C5H4, Fc), 72.4 (C5H4, Fc), 71.8 (C5H4, Fc), 70.4 (C5H4, Fc),70.2
69.0 (C5H4, Cp, Fc), 63.2 (C5H4, Fc), 62.9 (C5H4, Fc), 21.2 (s, CH3). 31P{1H} NMR (δ, 121.5 MHz, CDCl3, 298 K): 2.94 (t),
0.16 (d) (2JP
P = 27.1). IR (cm
1): ν(CtC) 2182 (sh), 2157 (s), ν(CdCHTol) 1632 (m). MALDI-TOF (+): m/z (%) 1399 [Ru(Cd CHTol)(PPh2CtCFc)3]+ (14), 1319 [RuCl(PPh2CtCFc)3]+ (62), 1040 [RuCl(CdCHTol)(PPh2CtCFc)2]+ (21), 1005 [Ru(CdCHTol)(PPh2CtCFc)2]+ (100). Anal. Calcd (%) for C81H65Cl2Fe3P3Ru: C, 66.15; H, 4.45. Found: C, 66.73; H, 4.65.

Synthesis of [trans-Ru(C;CR)2(PPh2C;CPh)4] (R = Ph trans5a, Tol trans-5b). To a solution of [trans-RuCl2(PPh2CtCPh)4] in

CH2Cl2 (20 mL) was added 4 equiv of NaPF6, 4 equiv of the acetylene (HCtCR) ligand, and 8 equiv of NEt3. The mixture was stirred for 8 h, and the resulting suspension filtered through Celite. The filtrate was concentrated in vacuo (∼2 mL), and addition of EtOH (5 mL) produced the precipitation of a pale yellow microcrystalline solid. Data for [trans-Ru(CtCPh)2(PPh2CtCPh)4], trans-5a. [trans-RuCl2(PPh2CtCPh)4] (0.14 g, 0.110 mmol), HCtCPh (49 μL, 0.440 mmol), NaPF6 (0.072 g, 0.440 mmol), and NEt3 (122 μL, 0.880 mmol) (0.054 g, 34% yield) were used. 1H NMR (δ, 300.1 MHz, CDCl3) at 223 K: 10.1 (s, br, o-H, PPh2), 7.59 (m, m-H, PPh2), 7.38 (m), 7.31 (m), 7.12 (m), 6.85 (m), 6.66 (m, o-H, PPh2), 6.45 (m, m-H, PPh2); at 293 K: ∼8.4 (br, o-H, PPh2), 7.63 (m), 7.40 (m), 7.28 (m), 7.12 (m), 6.83 (m), 6.68 (m, m-H). 13 C{1H} NMR (δ, 100.64 MHz, CDCl3, 293 K): 138.9 (q, 1+3JP
C ≈ 52, iC, PPh2), 132.65
122.9 (aromatics), 116.02 (tentatively assigned to Cβ, Ru-CRtCβ), 109.88 (tentatively assigned to Cβ, P-CRtCβ), 83.70 (AXX0 X00 2, 1+3JP
C ≈ 80.7, CR, P-CRtCβ). 31P{1H} NMR (δ, 121.5 MHz, CDCl3, 293 K): 4.24 (s). IR (cm
1): ν(CtC) 2180 (s, PPh2CtCPh),

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2061 (m, CtCPh). MALDI-TOF (+): m/z (%) 1162 [Ru(CtCPh)2(PPh2CtCPh)3]+ (5), 960 [Ru(PPh2CtCPh)3]+ (29), 876 [Ru(Ct CPh)2(PPh2CtCPh)2]+ (55), 674 [Ru(PPh2CtCPh)2]+ (100). Anal. Calcd (%) for C96H70P4Ru 3 CH2Cl2: C, 75.97; H, 4.73. Found: C, 75.73; H, 4.55. Data for [trans-Ru(CtCTol)2(PPh2CtCPh)4], trans-5b. [trans-RuCl2(PPh2CtCPh)4] (0.200 g, 0.15 mmol), HCtCTol (80 μL, 0.60 mmol), NaPF6 (0.102 g, 0.60 mmol), and NEt3 (173 μL, 1.20 mmol) (0.082 g, 37% yield) were used. 1H NMR (δ, 300.1 MHz, CDCl3) at 223 K: 10.2 (s, br, o-H, PPh2), 7.54 (m), 7.43 (m), 7.17 (m), 6.88 (m), 6.72 (m, o-H, PPh2), 6.51 (m, m-H, PPh2), 2.51 (6H, CH3); 293 K: ∼8.4 (br, o-H, PPh2), 7.53 (m), 7.41 (m), 7.31 (m), 7.12 (m), 6.81 (m), 6.67 (m, m-H, PPh2), 2.48 (6H, CH3). 13C{1H} NMR (100.64 MHz, CDCl3, 293 K): Due to the low solubility, only signals due to aromatic carbons were observed, δ 136.61
127.2. 31P{1H} NMR (δ, 121.5 MHz, CDCl3, 293 K): 4.44 (s). IR (cm
1): ν(CtC) 2181 (s, PPh2CtCPh), 2065 (m, CtCTol). MS ES(+): m/z (%) 1253 [Ru(PPh2CtCPh)4 + Li]+ (47), 1075 [Ru(CtCTol)(PPh2Ct CPh)3]+ (37), 967 [Ru(PPh2CtCPh)3 + Li]+ (100), 905 [Ru(Ct CTol)2(PPh2CtCPh)2 + H]+ (40). Anal. Calcd (%) for C98H74P4Ru 3 3/ 2CH2Cl2: C, 74.51; H, 4.84. Found: C, 74.83; H, 4.82.

Synthesis of [trans-Ru(C;CR)2(PPh2C;CTol)4] (R = Ph trans6a, Tol trans-6b). Complexes trans-6a and trans-6b were prepared as pale

yellow solids, using the same procedure as for trans-5, by treating a solution of [trans-RuCl2(PPh2CtCTol)4] with 4 equiv of NaPF6, 4 equiv of the acetylene (HCtCR) ligand, and 8 equiv of NEt3. Data for [trans-Ru(CtCPh)2(PPh2CtCTol)4], trans-6a. [transRuCl2(PPh2CtCTol)4] (0.130 g, 0.092 mmol), HCtCPh (41 μL, 0.368 mmol), NaPF6 (0.064 g, 0.368 mmol), and NEt3 (107 μL, 0.736 mmol) (0.064 g, 46% yield) were used. 1H NMR (δ, 300.1 MHz, CDCl3, 293 K): 8.35 (br, o-H, PPh2), 7.63 (m), 7.50 (m), 7.27 (m), 6.92 (d), 6.79 (d), 6.67 (m, m-H, PPh2), 2.36 (s, CH3). 13C{1H} NMR (100.64 MHz, CDCl3, 293 K): Due to the low solubility, only the signals of the aromatics and CH3 carbons were observed δ 139.0
126.0 (aromatics), 21.75 (CH3, PPh2CtCTol). 31P{1H} NMR (δ, 121.5 MHz, CDCl3, 293 K): 3.99 (s). IR (cm
1): ν(CtC) 2178 (s, PPh2CtCTol), 2062 (s, CtCPh). MALDITOF (+): m/z (%) 1204 [Ru(CtCPh)2(PPh2CtCTol)3]+ (3), 1103 [Ru(CtCPh)(PPh2CtCTol)3]+ (6), 1002 [Ru(PPh2CtCTol)3]+ (52), 702 [Ru(PPh2CtCTol)2]+ (100). Anal. Calcd (%) for C100H78P4Ru: C, 79.76; H, 5.23. Found: C, 79.63; H, 5.34. Data for [trans-Ru(CtCTol)2(PPh2CtCTol)4], trans-6b. [trans-RuCl2(PPh2CtCTol)4] (0.2 g, 0.146 mmol), HCtCTol (74 μL, 0.584 mmol), NaPF6 (0.098 g, 0.584 mmol), and NEt3 (163 μL, 1.168 mmol) (0.121 g, 54% yield) were used. 1H NMR (δ, 300.1 MHz, 293 K, CDCl3): ∼8.36 (br, o-H, PPh2), 7.94 (m) 7.52 (m), 7.31(m), 7.12 (m), 6.94 (m), 6.80 (m), 6.66 (m, m-H, PPh2), 6.49 (m), 2.50 (s, 6H, CH3), 2.37 (s, 12H, CH3). 13C{1H} NMR (δ, 100.64 MHz, CDCl3, 293 K): 139.4
127.1 (aromatics), 119.98 (tentatively assigned to Cβ, Ru-CRtCβ), 109.95 (tentatively assigned to Cβ, P-CRtCβ), 21.69 (CH3, PPh2CtCTol), 21.39 (CH3, CtCTol). 31P{1H} NMR (δ, 121.5 MHz, CDCl3, 293 K): 4.24 (s). IR (cm
1): ν(CtC) 2175 (s, PPh2CtCTol), 2064 (s, CtCPh). MALDI-TOF (+): m/z (%) 1117 [Ru(CtCTol)(PPh2CtCTol)3]+ (50), 932 [Ru(CtCTol)2(PPh2Ct CTol)2]+ (98), 1002 [Ru(PPh2CtCTol)3]+ (66), 817 [Ru(CtCTol)(PPh2CtCTol)2]+ (38), 702 [Ru(PPh2CtCTol)2]+ (100). Anal. Calcd (%) for C102H82P4Ru: C, 79.87; H, 5.39. Found: C, 79.66; H, 5.44.

Synthesis of [trans-Ru(C;CR)2(PPh2C;CFc)4] (R = Ph trans7a, Tol trans-7b). Complexes trans-7a and trans-7b were prepared as

orange solids using the same procedure as for trans-5, adding 4 equiv of NaPF6, 4 equiv of the acetylene (HCtCR) ligand, and 8 equiv of NEt3 to a solution of [trans-RuCl2(PPh2CtCFc)4]. In the case of trans-7a the final solid was recrystallized from CH2Cl2/Et2O. Data for [trans-Ru(CtCPh)2(PPh2CtCFc)4], trans-7a. [trans-RuCl2(PPh2CtCFc)4] (0.07 g, 0.040 mmol), HCtCPh (17 μL, 0.160 mmol), NaPF6 (0.026 g, 0.160 mmol), and NEt3 (47 μL, 0.320 mmol) (0.025 g, 4673

dx.doi.org/10.1021/om2005194 |Organometallics 2011, 30, 4665–4677

Organometallics 33% yield) were used. 1H NMR (δ, 300.1 MHz, CDCl3, 293 K): ∼8.40 (br, o-H, PPh2), 7.87 (m) 7.52 (m), 7.16 (m), 7.03 (m), 6.97 (m), 6.85 (m), 6.48 (m), 4.34 (s, C5H4, 4H), 4.24 (s, Cp, 20H), 4.20 (s, C5H4, 4H), 3.91 (s, C5H4, 8H). 31P{1H} NMR (δ, 121.5 MHz, CDCl3, 293 K): 5.90 (s). IR (cm
1): ν(CtC) 2182, 2158 (m, PPh2CtCFc), 2073 (m, CtCPh). MALDI-TOF (+): m/z (%) 1486 [Ru(CtCPh)2(PPh2CtCFc)3]+ (19), 1284 [Ru(PPh2CtCFc)3]+ (48), 1092 [Ru(CtCPh)2(PPh2CtCFc)]+ (100), 890 [Ru(PPh2CtCFc)2]+ (86). Anal. Calcd (%) for C112H86Fe4P4Ru: C, 71.54; H, 4.61. Found: C, 71.96; H, 4.87. Data for [trans-Ru(CtCTol)2(PPh2CtCFc)4], trans-7b. [transRuCl2(PPh2CtCFc)4] (0.1 g, 0.057 mmol), HCtCTol (28 μL, 0.228 mmol), NaPF6 (0.033 g, 0.228 mmol), and NEt3 (67 μL, 0.457 mmol) (0.062 g, 57% yield) were used. 1H NMR (δ, 300.1 MHz, CDCl3, 293 K): ∼8.42 (br, o-H, PPh2), 7.87 (m) 7.53 (m), 7.38 (m), 7.13 (m), 6.95 (m), 6.83 (m), 6.62 (m), 6.45 (m), 4.37 (s, C5H4, 8H), 4.22 (s, Cp, 20H), 3.91 (s, C5H4, 8H), 2.35 (s, 6H, CH3). 31P{1H} NMR (δ, 121.5 MHz, CDCl3, 293 K): 5.30 (s). IR (cm
1): ν(CtC) 2185, 2163 (s, PPh2CtCFc), 2065 (s, CtCTol). MALDI-TOF (+): m/z (%) 1513 [Ru(CtCTol)2(PPh2Ct CFc)3]+ (12), 1399 [Ru(CtCTol)(PPh2CtCFc)3]+ (9), 1284 [Ru(PPh2CtCFc)3]+ (41), 1120 [Ru(CtCTol)2(PPh2CtCFc)2]+ (100), 890 [Ru(PPh2CtCFc)2]+ (77). Anal. Calcd (%) for C114H94Fe4P4Ru: C, 71.60; H, 4.95. Found: C, 71.32; H, 5.17.

Synthesis of [cis-Ru(C;CR)2(PPh2C;CPh)4] (R = Ph cis-5a, Tol cis-5b). A mixture of [trans-RuCl2(PPh2CtCPh)4], HCtCR (4

equiv), and NEt3 (1 mL) in CH2Cl2 (20 mL) was stirred for 6 h and concentrated in vacuo to ∼2 mL. Addition of diethyl ether (5 mL) resulted in the precipitation of the products as beige solids. Data for [cis-Ru(CtCPh)2(PPh2CtCPh)4], cis-5a. [trans-RuCl2(PPh2CtCPh)4] (0.14 g, 0.110 mmol), HCtCPh (49 μL, 0.440 mmol), and NEt3 (1 mL) (0.040 g, 25% yield) were used. 1H NMR (δ, 300.1 MHz, CDCl3, 293 K): ∼8.32 (br, o-H, PPh2), 8.04, 7.55 (m), 7.30 (m), 7.25 (m), 7.12 (m), 6.84 (m), 6.68 (m). 31P{1H} NMR (δ, 162 MHz, CDCl3, 293 K): 2.82 (t)
3.78 (t) (2JP
P = 37.2). IR (cm
1): ν(CtC) 2180 (s, PPh2Ct CPh), 2075 (m, CtCPh). MALDI-TOF (+): m/z (%) 1061 [Ru(Ct CPh)(PPh2CtCPh)3]+ (100), 775 [Ru(CtCPh)(PPh2CtCPh)2]+ (88). Anal. Calcd (%) for C96H70P4Ru: C, 75.60; H, 4.87. Found: C, 75.51; H, 4.65. Data for [cis-Ru(CtCTol)2(PPh2CtCPh)4], cis-5b. [trans-RuCl2(PPh2CtCPh)4] (0.100 g, 0.076 mmol), HCtCTol (40 μL, 0.30 mmol), and NEt3 (1 mL) (0.032 g, 28% yield). 1H NMR (δ, 300.1 MHz, CDCl3, 293 K): ∼8.30 (br, o-H, PPh2), 8.09 (m), 7.62 (m), 7.37 (m), 7.17 (m), 6.88 (m), 6.72 (m) (68H, aromatics), 2.53 (s, 6H, CH3). 31P{1H} NMR (δ, 162 MHz, CDCl3, 293 K): 2.75 (t)
3.48 (t) (2JP
P = 37.3). IR (cm
1): ν(CtC) 2176 (s, PPh2CtCPh), 2080 (s, CtCTol). MALDITOF (+): m/z (%) 1362 [Ru(CtCTol)(PPh2CtCPh)4]+ (3), 1248 [Ru(PPh2CtCPh)4 + 2H]+ (9), 1077 [Ru(CtCTol)(PPh2CtCPh)3 + H]+ (100), 789 [Ru(CtCTol)(PPh2CtCPh)2]+ (40), 674 [Ru(PPh2CtCPh)2]+ (42). Anal. Calcd (%) for C98H74P4Ru: C, 79.71; H, 5.05. Found: C, 79.68; H, 5.21.

Synthesis of [cis-Ru(C;CR)2(PPh2C;CTol)4] (R = Ph cis-6a, Tol cis-6b). Complexes cis-6a and cis-6b were prepared as beige solids

using the same procedure as for cis-5, from a mixture of [trans-RuCl2(PPh2CtCTol)4], HCtCR (4 equiv), and NEt3 (1 mL). Data for [cis-Ru(CtCPh)2(PPh2CtCTol)4], cis-6a. [trans-RuCl2(PPh2CtCTol)4] (0.100 g, 0.073 mmol), HCtCPh (32 μL, 0.291 mmol), and NEt3 (1 mL) (0.040 g, 36% yield) were used. 1H NMR (δ, 400 MHz, CDCl3, 293 K): ∼8.05 (br, o-H, PPh2), 7.98 (d), 7.65 (m), 7.41 (d), 7.35 (m), 7.25 (d), 6.98 (d), 6.87 (m), 6.70 (m), (72H, aromatics), 2.55 (s, 6H, CH3), 2.41 (s, 6H, CH3). 31P{1H} NMR (δ, 162 MHz, CDCl3, 293 K): 2.64 (t),
4.10 (t) (2JP
P = 37.1). IR (cm
1): ν(CtC) 2174 (s, PPh2CtCTol), 2072 (s, CtCPh). MALDI-TOF (+): m/z (%) 1103 [Ru(CtCPh)(PPh2CtCTol)3]+ (53), 803 [Ru(CtCPh)(PPh2Ct CTol)2]+ (34). Anal. Calcd (%) for C100H78P4Ru: C, 79.76; H, 5.23. Found: C, 79.64; H, 5.32.

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Data for [cis-Ru(CtCTol)2(PPh 2CtCTol)4], cis-6b. [trans-RuCl2(PPh2CtCTol)4] (0.100 g, 0.073 mmol), HCtCTol (37 μL, 0.291 mmol), and NEt 3 (1 mL) (0.042 g, 39% yield) were used. 1H NMR (δ, 400 MHz, CDCl 3, 293 K): ∼ 8.37 (br, o-H, PPh 2), 7.98 (d) 7.54 (d), 7.41 (d), 7.27 (d), 7.17 (d), 6.97 (d), 6.86 (m), 6.71 (m), 2.55 (s, 12H, CH 3, PCtCTol, Ru-CtCTol), 2.38 (s, 6H, CH3 , PCtCTol). 31 P{1H} NMR (δ, 162 MHz, CDCl3 , 293 K): 2.62 (t),
3.66 (t) (2JP
P = 37.2). IR (cm
1): ν(CtC) 2176 (s, PPh2Ct CTol), 2075 (s, CtCTol). MALDI-TOF (+): m/z (%) 1117 [Ru(CtCTol)(PPh2CtCTol)3]+ (21), 1002 [Ru(PPh2CtCTol)3]+ (96), 932 [Ru(CtCTol)2(PPh2CtCTol)2]+ (100), 817 [Ru(CtCTol) (PPh2CtCTol)2]+ (12), 702 [Ru(PPh2CtCTol)2]+ (89). Anal. Calcd (%) for C102H82P4Ru: C, 79.87; H, 5.39. Found: C, 79.76; H, 5.43.

Synthesis of [cis-Ru(C;CR)2(PPh2C;CFc)4] (R = Ph cis-7a, Tol cis-7b). Complexes cis-7a and cis-7b were prepared stirring for 2 h a mixture

of [trans-RuCl2(PPh2CtCFc)4], HCtCR (4 equiv), and NEt3 (1 mL) in CH2Cl2 (20 mL). Evaporation to ∼2 mL and addition of diethyl ether (5 mL) resulted in the precipitation of cis-7a and cis-7b as orange solids. Data for [cis-Ru(CtCPh)2(PPh2CtCFc)4], cis-7a. [trans-RuCl2(PPh2CtCFc)4] (0.100 g, 0.057 mmol), HCtCPh (25 μL, 0.228 mmol), and NEt3 (1 mL) (0.062 g, 57% yield) were used. 1H NMR (δ, 300.1 MHz, CDCl3, 293 K): ∼8.2 (br, o-H), 7.90 (m), 7.46 (m), 6.96 (m), 6.87 (m), 6.50 (m), 4.75 (s, Fc), 4.38 (s, Fc), 4.22 (s, Fc), 3.89 (s, Fc). 31P{1H} NMR (δ, 121.5 MHz, CDCl3, 293 K): 3.17 (t),
2.77 (t) (2JP
P = 36.8). IR (cm
1): ν(CtC) 2181, 2163 (s) (PPh2CtCFc), 2073 (m, CtCPh). MALDI-TOF (+): m/z (%) 1385 [Ru(CtCPh)(PPh2CtCFc)3]+ (100), 991 [Ru(CtCPh)(PPh2CtCFc)2]+ (98), 890 [Ru(PPh2CtCFc)2]+ (10). Anal. Calcd (%) for C112H86Fe4P4Ru: C, 71.54; H, 4.61. Found: C, 71.87; H, 4.92. Data for [cis-Ru(CtCTol)2(PPh2CtCFc)4], cis-7b. [trans-RuCl2(PPh2CtCFc)4] (0.100 g, 0.057 mmol), HCtCTol (28 μL, 0.228 mmol), and NEt3 (1 mL) (0.058 g, 53% yield) were used. 1H NMR (δ, 300.1 MHz, 293 K, CDCl3): ∼8.2 (br), 8.05 (br), 7.59 (br) 7.26 (s, br), 6.97 (s, br), 6.51 (br), 4.76 (s, Fc), 4.38 (s, Fc), 4.23 (s, Fc), 2.37 (s, CH3, Tol). 31 1 P{ H} NMR (δ, 121.5 MHz, CDCl3, 293 K): 3.18 (t),
2.55 (t) (2JP
P = 37.5). IR (cm
1): ν(CtC) 2182, 2161 (m) (PPh2CtCTol), 2079 (m, CtCTol). MALDI-TOF (+): m/z (%) 1399 [Ru(CtCTol)(PPh2Ct CFc)3]+ (9), 1284 [Ru(PPh2CtCFc)3]+ (41), 1120 [Ru(CtCTol)2(PPh2CtCFc)2]+ (100), 890 [Ru(PPh2CtCFc)2]+ (77). Anal. Calcd (%) for C114H94Fe4P4Ru: C, 71.60; H, 4.95. Found: C, 71.92; H, 4.73.

Synthesis of [mer-Ru{kC,O-C(CH2COCH3)dCHPh}Cl(PPh2C;CPh)3] (8). A mixture of [trans-RuCl2(PPh2CtCPh)4]

(0.140 g, 0.110 mmol), HCtCPh (49 μL, 0.440 mmol), and NEt3 (1 mL) in CH2Cl2 (20 mL) was stirred for 2 h. Partial evaporation (∼2 mL) and addition of diethyl ether (5 mL) resulted in precipitation of 0.040 g of pure complex cis-5a. The filtratre was evaporated to dryness, and the residue treated with acetone and filtered. The resulting yellow filtrate was evaporated to dryness, and the residue was recrystallized from CH2Cl2/ hexane to give 8 as a yellow microcrystalline solid (0.022 g, 17%). 1H NMR (δ, 300.1 MHz, CDCl3, 293 K): 8.08 (d), 8.02 (m), 7.62 (m), 7.55 (m), 7.45 (m), 7.07 (m), 6.92 (m), 6.80 (d) (50H, aromatics), 4.57 (s, 1H, CH, CdCHPh), 2.30 (s, 3H, CH3, OdC(CH3)CH2), 1.26 (s, tentatively assigned to CH2, overlapping with residual signal of hexane). 13C{1H} NMR (δ, 100.64 MHz, CDCl3, 293 K): 180.8 (s, CO), 140.2
122.54 (aromatics), 120.51 (d, 3JC
P ≈ 4.5, CH, CdCHPh), 109.46 (s br, Cβ, P-CRtCβ, trans to P), 107.80 (d, Cβ,2JC
P ≈ 2.6, P-CRtCβ, trans to C), 83.5 (d, 1JP
C = 63.1, CR, P-CRtCβ, trans to C), 83.3 (AXX0 , 1+3JP
C = 62.9, CR, P-CRtCβ, trans to P), 45.87 (s, CH2), 20.34 (s, CH3). 1H and 13 C{1H} NMR spectra assignments have been done based on heteropolynuclear 1H
13C (HSQC, HMBC) correlations experiments. 31P{1H} NMR (δ, 121.5 MHz, CDCl3) at 240 K: 13.94 (AB2 system, 1P, J = 25), 13.42 (2P); at 293 K: 13.2 (s). IR (cm
1): ν(CtC) 2172 (s), ν(CdC; CdO) 1621 (s), 1592 (s). MALDI-TOF (+): m/z (%) 1061 [M
Cl
acetone + H]+ (5), 1019 [Ru(PPh2CtCPh)3(CH3COCH3) + H]+ (8), 4674

dx.doi.org/10.1021/om2005194 |Organometallics 2011, 30, 4665–4677

Organometallics

ARTICLE

Table 4. Crystallographic Data for 3, trans-5a, and 8 3 0.5(CH3COCH3) trans-5a

3

trans-7a 3 2CHCl3 3 2hexane

8 3 0.5(CH3COCH3)

empirical formula

C96H76Cl2Fe4P4Ru

C96H70P4Ru

C114H88Cl6Fe4P4Ru

C72.5H59ClO1.5P3Ru

fw

1748.82

1448.47

2291.37

1183.71

temperature (K)

100(1)

223(1)

130(1)

173(1)

wavelength (Å)

0.71073

0.71073

0.71073

0.71073

cryst syst

tetragonal

orthorhombic

tetragonal

orthorhombic

space group

P4/21/c

P4/21/c

I4

P21/21/21

a (Å); R (deg)

19.5247(8); 90

12.8180(2); 90

15.310(5); 90

13.5500(3); 90

b (Å); β (deg) c (Å); γ (deg)

19.5247(8); 90 9.9352(3); 90

12.8180(2); 90 22.8460(3); 90

15.310(5); 90 23.666(5); 90

18.1803(5); 90 27.7471(5); 90

V (Å3); Z

3787.4(2); 2

3753.62(10); 2

5547(3); 2

6835.3(3); 4

calcd density (Mg/m3)

1.533

1.282

1.372

1.150

abs coeff (mm
1)

1.148

0.342

0.890

0.376

F(000)

1788

1500

2164

2384

cryst size (mm3)

0.10  0.10  0.10

0.35  0.30  0.15

0.50  0.50  0.45

0.45  0.35  0.15

2θ range (deg)

3.76 to 26.37

2.39 to 26.36

1.58 to 27.45

3.10 to 26.37

index ranges


18 e h e 24
24 e k e 24


15 e h e 16
11 e k e 15


19 e h e 19
19 e k e 19


16 e h e 16 0 e k e 22


9 e l e 12


28 e l e 28


30 e l e 30

0 e l e 34

reflns collected

20 200

19 700

35 784

13 744

indep reflns

3854 [R(int) = 0.0673]

3839 [R(int) = 0.0377]

6294 [R(int) = 0.0697]

13 744 [R(int) = 0.0000]

data/restraints/params

3854/0/242

3839/0/230

6294/3/241

13 744/0/694

goodness of fit on F2a

0.857

1.037

1.126

1.056

final R indices [I > 2σ(I)]a

R1 = 0.0421, wR2 = 0.0889

R1 = 0.0269, wR2 = 0.0612

R1 = 0.0854, wR2 = 0.2166

R1 = 0.0349, wR2 = 0.0929

R indices (all data)a largest diff peak and hole (e Å
3)

R1 = 0.0552, wR2 = 0.0960 1.108 and
0.289

R1 = 0.0341, wR2 = 0.0664 0.323 and
0.238

R1 = 0.0895, wR2 = 0.2212 2.220 and
0.798

R1 = 0.0412, wR2 = 0.0959 0.497 and
0.572

R1 = ∑(|Fo|
|Fc|)/∑|Fo|; wR2 = [∑w(Fo2
Fc2)2/∑wFo2]1/2; goodness of fit = {∑[w(Fo2
Fc2)2]/(Nobs
Nparam)}1/2; w = [σ2(Fo) + (g1P)2 + g2P]
1; P = [max(Fo2; 0 + 2Fc2]/3. a

810 [RuCl(CtCPh) (PPh2CtCPh)2 + H]+ (60). Anal. Calcd (%) for C72H57ClOP3Ru 3 CH2Cl2: C, 73.79; H, 4.97. Found: C, 73.73; H, 4.95. X-ray Crystallography. Details of the structural analyses for all complexes are summarized in Table 4. Orange (3), yellow (trans-5a, 8), or red (trans-7a) crystals were obtained by slow diffusion at
30 °C of nhexane (3, trans-7a, 8) or acetone (trans-5a) into the respective solutions of the complexes in CH2Cl2 (3, trans-5a), CHCl3 (trans-7a), or acetone (8). X-ray intensity data were collected with a NONIUS-kCCD area-detector diffractometer, using graphite-monochromated Mo KR radiation. Images were processed using the DENZO and SCALEPACK suite of programs,44 and the absorption corrections were performed using SORTAV.45 The structures were solved by direct methods using SHELXS-97 (3)46 or by direct and Patterson methods using SIR2004 (trans-5a, trans-7a, and 8)47 and refined by full-matrix least-squares on F2 with SHELXL-97.46 All nonhydrogen atoms were assigned anisotropic displacement parameters, and the hydrogen atoms were constrained to idealized geometries fixing isotropic displacement parameters 1.2 times the Uiso value of their attached carbon for aromatic or methylenic hydrogens and 1.5 times for the methyl groups. For complex trans-7a, which crystallizes in the non-centrosymmetric space group P4, the crystal chosen for this structural analysis was found to be an inversion twin with occupancy 0.10(4) for the second component. Finally, although no peaks bigger than 1 e Å
3 were observed in the electron density map, inspection of the structure of complexes trans-7a and 8 with PLATON48 showed the presence of a large solvent-accessible void. The use of SQUEEZE49 revealed two clear voids of 215 Å3 (each of them containing 97 electrons in the unit cell, which fits well with the presence of 0.5 molecule of hexane in each asymmetric unit) for trans-7a and other two clear voids of 836 Å3 (each of them containing 36 electrons in the unit cell, which fits well with the presence of 0.5 molecule of acetone in each asymmetric unit).

Therefore, we have included them in the empirical formula as crystallization solvent [trans-7a 3 2CHCl3 3 2hexane, 8 3 0.5(CH3)2CO].

’ COMPUTATIONAL DETAILS All DFT calculations were carried out using the Gaussian 03 package.50 All calculations applied the Becke’s three-parameter hybrid function combined with the Lee
Yang
Parr correlation function (B3LYP).51 The basis set used was the LanL2DZ52 effective core potential for the metal center (Ru) and 6-31G(d,p) for the ligand atoms. Both [trans-Ru(CtCPh)2(PPh2CtCPh)4] (trans-5a) and [cis-Ru(CtCPh)2(PPh2CtCPh)4] (cis-5a) isomers were optimized under vacuum, and no negative values were found in the results of the vibrational frequency analysis.

’ ASSOCIATED CONTENT P{1H} and 1H NMR spectra of 3 in CDCl3 at 223 and 293 K (Figure S1). View of the short C
H 3 3 3 (CtC) contacts in trans-5a and trans-7a (Figure S2). View of the molecular structure of 8 showing the weak secondary Cl 3 3 3 H, O 3 3 3 H, and C
H 3 3 3 (CtC) contacts (Figure S3). CV of complex 3 in CH2Cl2 at 25 and
50 °C (Figure S4). CV of complex 4a in CH2Cl2 at 25 °C (Figure S5). CV (first and second scan) of complex trans-7b in CH2Cl2 at 25 °C (Figure S6). CV (first and second scan) and DPV of complex trans-7a in CH2Cl2 at 25 °C (Figure S7). Spectroscopic changes upon gradual oxidation of [mer, cis-RuCl2(CdCHTol)(PPh2CtCPh)3] and 4b in CH2Cl2 in an OTTLE cell (Figures S8
S10). Coordinates after optimization of complexes trans-5a and cis-5a (Tables S1, S2). DFT-optimized

bS

4675

Supporting Information.

31

dx.doi.org/10.1021/om2005194 |Organometallics 2011, 30, 4665–4677

Organometallics structures trans-5a and cis-5a (Figures S11, S12). Comparison of selected distances found in X-ray diffraction studies and DFT optimized for trans-5a (Table S3). Composition of frontier MO for complexes trans-5a and cis-5a (Table S4) and complete ref 50. This material is available free of charge via the Internet at http://pubs.acs.org.

’ AUTHOR INFORMATION Corresponding Author

*Fax: (+34) 941 299 621. E-mail: [email protected].

’ ACKNOWLEDGMENT This work was supported by the Spanish MICINN (Project CTQ2008-06669-C02-02/BQU and a grant for S.R.). J.F. thanks the CAR (COLABORA Project 2009/05) and S.S. thanks the CSIC for a grant. We also thank CESGA for computer support. ’ REFERENCES (1) (a) Berenguer, J. R.; Lalinde, E.; Moreno, M. T. Coord. Chem. Rev. 2010, 254, 832. (b) Mathur, P.; Chatterjee, S.; Avasare, V. D. Adv. Organomet. Chem. 2007, 55, 201. (2) Long, N. J.; Williams, C. K. Angew. Chem., Int. Ed. 2003, 42, 2586. (3) (a) Jones, S. C.; Coropceanu, V.; Barlow, S.; Kinnibrugh, T.; Timofeeva, T.; Br
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