Bis(metallaethynyl) Ketones: Synthesis and Structure of {(Ph3P)AuC

ARTICLE pubs.acs.org/Organometallics

Bis(metallaethynyl) Ketones: Synthesis and Structure of {(Ph3P)AuC;C}2CO and Attempted Transmetalation: Formation and Structure of [1,3-{Ru(dppe)Cp}2{c-COC(OMe)CHCCH}]PF6 David J. Armitt,† Michael I. Bruce,*,† Jonathan C. Morris,‡ Brian K. Nicholson,§ Christian R. Parker,† Brian W. Skelton,|| and Natasha N. Zaitseva† †

School of Chemistry & Physics, University of Adelaide, Adelaide, South Australia 5005, Australia School of Chemistry, University of New South Wales, Sydney, New South Wales 2052, Australia § Department of Chemistry, University of Waikato, Hamilton, New Zealand Centre for Microscopy, Characterisation and Analysis, University of Western Australia, Crawley, Western Australia 6009, Australia

)

‡

bS Supporting Information ABSTRACT:

The bis(metallaethynyl) ketone {(Ph3P)AuCtC}2CO (1), obtained from (Me3SiCtC)2CO, AuCl(PPh3), and NaOMe, forms an Au 3 3 3 Au-bonded dimer in the solid state (Au 3 3 3 Au = 2.9825(3) Å). The ES-MS contains ions [2M + X]+ (X = Na, K, Au), but the lack of the ion [2M]+ and NMR evidence suggest that the dimeric structure is not preserved in solution. Compound 1 reacts with RuCl(dppe)Cp to afford the unusual dimetal-substituted pyrylium complex [1,3-{Ru(dppe)Cp}2{c-COC(OMe)CHCCH}]PF6 (2). The molecular structure of 2 is also reported, together with a proposed route for its formation.

’ INTRODUCTION Compounds containing redox-active metal
ligand fragments linked by unsaturated hydrocarbon chains continue to attract attention,1,2 particularly those containing redox-active end groups capping
{C(sp)}n
chains.3
6 The effects of inserting some group X into a
(CtC)x
chain on the electronic communication between the end groups along the chain has been the object of recent studies: for example, where X = aryl, naphthyl, anthryl.7 We have begun a study of the effects of the insertion of groups such as CdCH2, or the strongly electron-withdrawing CdO or CdC(CN)2, into the carbon chain.8 The transmetalation reaction, whereby a gold(I) phosphine group is replaced by ruthenium, is a useful route to alkynylruthenium complexes.9,10 Accordingly, we have investigated the use of {(Ph3P)AuCtC}2CO (1), synthesized here for the first time, as a possible source of the bis(ruthenaethynyl) ketone {Cp(dppe)RuCtC}2CO. However, the product proved to be an unprecedented dimetallapyrylium complex. r 2011 American Chemical Society

’ RESULTS AND DISCUSSION (a). Synthesis and Molecular Structure of {(Ph3P)AuC;C}2CO (1). The gold-containing bis(ethynyl) ketone {(Ph3P)-

AuCtC}2CO (1) apparently has not been previously described and was synthesized in 50% yield by a rather sluggish aurodesilylation reaction between (Me3SiCtC)2CO and AuCl(PPh3) in THF
MeOH in the presence of NaOMe (Scheme 1). An alternative approach from (Pri3SiCtC)2CO, AuCl(PPh3), and [NBu4]F in THF gave 1 in 27% yield. Complex 1 was obtained as a white crystalline solid and was identified from elemental microanalysis and its spectroscopic features, the IR spectrum containing ν(CtC) and ν(CO) bands at 2106 and 1593 cm
1, respectively. The latter band is at an energy significantly lower than those found in the precursor (Me3SiCtC)2CO (1622 cm
1) Received: July 21, 2011 Published: September 29, 2011 5452

dx.doi.org/10.1021/om200659t | Organometallics 2011, 30, 5452–5456

Organometallics Scheme 1. Synthesis of {(Ph3P)AuCtC}2CdO (1)

Figure 1. Plot of a molecule of {[(Ph3P)AuCtC]2CO}2 (1) (H atoms omitted for clarity). Selected bond distances (Å) and angles (deg): Au(1) 3 3 3 Au(3) = 2.9825(3), Au(1)
P(1) = 2.281(2), Au(1)
C(11) = 2.031(6), C(11)
C(12) = 1.184(9), C(12)
C(13) = 1.448(10), C(13)
O(13) = 1.219(8); P(1)
Au(1)
C(11) = 179.3(2), Au(1)
C(11)
C(12) = 168.6(6), C(11)
C(12)
C(13) = 175.4(8), C(12)
C(13)
C(14) = 115.3(6), C(12)
C(13)
O(13) = 122.5(6).

or in (HCtC)2CO (1669 cm
1),11 perhaps reflecting the donor power of the Au(PPh3) substituent. The X-ray-determined structure of 1 (Figure 1) consists of dimeric molecules, the halves of which are linked by a short aurophilic Au 3 3 3 Au interaction (2.9825(3) Å). Each half of the molecule has the expected structure, with Au
C(sp) bond lengths between 1.985 and 2.031(6) Å, CtC triple bond lengths between 1.180 and 1.210(9) Å, and CdO bond lengths of 1.219 and 1.220(8) Å. The P
Au
CtC
C moieties are essentially linear, with angles at atoms within the chains being between 168.6 and 179.3(2)°. The central PAuCCC(O)CCAuP atoms of each half are essentially planar, with the dihedral angle between the planes of the two moieties being 92.59(4)°. The 13C NMR spectra contains two doublet resonances for the C(sp) carbon atoms (δC 105.06 for C(2,4) and 139.20 for

ARTICLE

C(1,5) with J(CP) = 24, 134 Hz, respectively). However, there is only one Au(PPh3) resonance at δP 40.7, while the ES-MS spectrum of a solution in MeOH included only monomeric [M + H]+ and [M + Na]+ ions at m/z 995 and 1017, respectively. The dimeric ion [2M]+ was not detected, and with the NMR results, this suggests that facile dissociation of the dimer occurs in solution. The aggregate ions [2M + X]+ (X = Na, K, Au), [(2M + Na) PPh3]+, and [M + Au(PPh3)2]+ were also present and probably result from interactions of the cationic metal centers with the carbonyl groups. The compositions of these ions were confirmed by high-resolution measurements. (b). Reaction between RuCl(dppe)Cp and {(Ph3P)AuC;C}2CO (1). Transmetalation reactions between Au(CtCR)(PPh3) and halo
metal centers, [M]X, give [M]CtCR and AuX(PPh3).10,11 Treatment of {(Ph3P)AuCtC}2CO (1) with RuCl(dppe)Cp and [NH4]PF6 (used to provide the counteranion in the product) in methanol at reflux, followed by addition of DBU, afforded the bright yellow solid 2 (Scheme 2). However, the lack of any ν(CtC) or ν(CO) bands in the IR spectrum, together with the 31P NMR spectrum (below), suggested that the desired {[Cp(dppe)Ru]CtC}2CO had not formed, with this supposition being confirmed by a single-crystal structure determination of 2. A plot of the cation in 2 is shown in Figure 2. The structure determination revealed that 2 has the formulation [1,3-{Ru(dppe)Cp}2{μ-c-COC(OMe)CHCCH}]PF6, containing a pyrylium ring bearing two Ru(dppe)Cp groups at the 1,3positions. These groups have the usual pseudo-octahedral geometry (Ru
P = 2.236
2.264(1) Å, Ru
C(cp) = 2.25 Å (average), P
Ru
P = 84.39, 83.75(4)°, P
Ru
C = 84.3
93.3(1)°). Within the pyrylium ligand, electron delocalization results in longer than normal CdC bonds (C(1)
C(2) = 1.393(6) Å, C(4)
C(5) = 1.353(6) Å) with C(2)
C(3) and C(3)
C(4) (1.416(6), 1.428(6) Å) being shorter than C
C bonds, consistent with the pyrylium ligand displaying aromaticity. Bonds to the ring O atom C(1,5)
O(6) are 1.393(5) and 1.341(5) Å, respectively, the latter being the same as C(5)
O(5), while the terminal ether C(51)
O(5) bond length (1.437(5) Å) is considerably longer. Bond angles within the ring range from 114.0(4) to 129.1(4)°, with C(5)
O(5)
C(51) being 115.5(3)°. The Ru
C(1,3) bond lengths are 2.030(4) and 2.073(4) Å, consistent with Ru
C single bonds in both cases. Further, the Ru
P distances (2.260, 2.264(1) Å), which usually indicate a positive charge of the metal center by a lengthening over values found in analogous neutral derivatives, show only a small increase in the Ru(1)
P(1,2) bond lengths from those found in neutral complexes, e.g., 2.240 and 2.250(1) Å in Ru(CtCPh)(dppe)Cp.12 Consequently, these data, together with lengthening of the C(1)
C(2) and shortening of the C(2)
C(3) bonds, suggest that the positive charge is located within the pyrylium ring. Spectroscopic data are consistent with the solid-state structure. The IR spectrum contains ν(CdC) and ν(CdO) bands between 1567 and 1015 cm
1 and a ν(PF) band at 836 cm
1, while the 31P NMR spectrum displays two singlets for the two Ru(dppe)Cp groups at δP 93.0 and 90.9 and a septet at δP
142.2 (PF6). The 1H and 13C NMR spectra showed the expected peaks for the ancillary ligands, together with a singlet at δH 5.05 assigned to the C(4) proton. The OMe group resonates at δH 2.58 and δC 54.78, the former being at a field considerably higher than that found in related compounds Fe{c-CdCHCR1CPhCC(OMe)}(CO)2CpR (R = H, R1 = H, Ph; R = Me, R1 = H), in which the OMe group lies between the Fe and pyrylium O 5453

dx.doi.org/10.1021/om200659t |Organometallics 2011, 30, 5452–5456

Organometallics

ARTICLE

Scheme 2. Formation of [1,3-{Ru(dppe)Cp}2{μ-c-COC(OMe)CHCCH}]PF6 (2)a

a

Crystallographic numbering for 2 shown.

Scheme 3. Proposed Mechanisms for the Formation of 2a

Figure 2. Plot of the cation of [1,3-{Ru(dppe)Cp}2{c-COC(OMe)CHCCH}]PF6 (2) (H atoms omitted for clarity). Selected bond distances (Å) and angles (deg): Ru(1)
P(1,2) = 2.260, 2.264(1), Ru(2)
P(3,4) = 2.242, 2.236(1), Ru(1)
C(1) = 2.030(4), Ru(2)
C(3) = 2.073(4), C(1)
C(2) = 1.393(6), C(2)
C(3) = 1.416(6), C(3)
C(4) = 1.428(6), C(4)
C(5) = 1.353(6), C(1)
O(6) = 1.393(5), C(5)
O(5,6) = 1.341(5), 1.341(5), C(51)
O(5) = 1.437(5); P(1)
Ru(1)
P(2) = 84.39(4), P(3)
Ru(2)
P(4) = 83.75(4), P(1,2)
Ru(1)
C(1) = 93.3(1), 85.4(1), P(3,4)
Ru(2)
C(3) = 84.3(1), 92.4(1), Ru(1)
C(1)
C(2) = 128.2(3), Ru(1)
C(1)
O(6) = 117.1(1), C(1)
C(2)
C(3) = 126.0(4), C(2)
C(3)
C(4) = 114.0(4), C(3)
C(4)
C(5) = 120.1(4), C(2)
C(1)
O(6) = 114.2(4), C(4)
C(5)
O(6) = 123.0(4)°.

atoms.13 The C(2)H signal falls within the aromatic region, as do the resonances for C(2,4), which lie between δC 127 and 143.5. The two Ru
C(1,3) triplets are at δC 212.88 and 215.51. The ES-MS contains ion clusters at m/z 1239 (M+) and 565 ([Ru(dppe)Cp]+). This is an interesting structure: while there has been a significant amount of work on aromatic pyrylium cations,14 there are relatively few reports of transition-metal derivatives containing pyrylium ligands. Pyrylium cations with Cr(CO)3(η6-C6H5
), (Mn or Re)(CO)3(η5-C5H4
), Co2(CO)6(μ-alkynyl),15 or ferrocenyl15,16 substituents were investigated by Caro’s group. Other ferrocenyl derivatives are known.17 Cationic manganese and iron complexes have been described,13,18 while (η5-pyranyl)Mn(CO)3 and 2-ferrocenylpyrylium cations have been obtained from cyclomanganated chalcones and alkynes.19 A platinum(II) complex containing a related carbenoid ligand, cis-PtCl2(PPh3){c-CC(CO2Et)CPhC(CO2Et)CPhO}, was obtained from PtCl2(CO)2

a

[Ru] = Ru(dppe)Cp.

and PhCtCCO2Et, followed by reaction with PPh3, and is the only complex of this type which has been structurally characterized.20 Previous syntheses of metal complexes containing pyrylium ligands have proceeded from alkynes containing esters or other carbonyl groups via cyclization reactions involving C
C and C
O bond formation.19,20 In the present case, the stereochemistry 5454

dx.doi.org/10.1021/om200659t |Organometallics 2011, 30, 5452–5456

Organometallics of the precursor bis(ethynyl) ketone suggests that intramolecular reactions of this type would be difficult. Two possible mechanisms for the formation of 2 are shown in Scheme 3. Although the metal centers in Scheme 3 are depicted as [Ru] = Ru(dppe)Cp, in accord with the structure of the isolated product 2, we cannot be certain at what stage the transmetalation of the bis(metallaethynyl) ketone occurs. However, the presence of the ruthenium center would activate the alkynyl group to the reactions proposed, while recent studies have demonstrated the ability of gold(I) (here present in solution after transmetalation) to catalyze the rearrangement of propargylic esters21 and syntheses of pyrones from terminal alkynes and propiolic esters.22 Pathway A envisages attack of methoxide on the vinylidene 3, formed by protonation ([NH4]+) of the bis(ruthenaethynyl) ketone, to give intermediate 4. Intramolecular attack on Cα then affords acetal 5. Rearrangement by opening the oxetene ring would result in formation of the product 2 directly. Alternatively, rapid addition of MeOH to generate the hemiacetal (pathway B) is followed by a 1,3-shift of one metallaalkynyl group to Cα of the other, with concomitant isomerization to the corresponding allene. Tautomerization followed by cyclization via attack of the ester carbonyl at Cα of the remaining metallaalkynyl group and protonation affords the observed product 2.

’ CONCLUSIONS This paper describes the synthesis and characterization of {(Ph3P)AuCtC}2CO (1), which is a dimer by an Au 3 3 3 Au interaction in the solid state. Attempted transmetalation of 1 with RuCl(dppe)Cp did not give the desired bis(ruthenaethynyl) ketone but instead the unprecedented binuclear pyrylium complex 2. The molecular structures of 1 and 2 have been determined from single-crystal X-ray diffraction studies. A plausible mechanism is proposed for the formation of 2; further work is necessary to elucidate the route to 2 in detail. ’ EXPERIMENTAL SECTION General Considerations. All reactions were carried out under dry nitrogen, although normally no special precautions to exclude air were taken during subsequent workup. Common solvents were dried, distilled under nitrogen, and degassed before use. Separations were carried out by preparative thin-layer flash chromatography on silica gel (Davisil, 40
63 micron). Instruments. IR spectra were measured with a Bruker IFS28 FT-IR spectrometer. Nujol mull spectra were obtained from samples mounted between NaCl discs. NMR spectra were obtained with a Varian 2000 instrument (1H at 300.13 MHz, 13C at 75.47 MHz, 31P at 121.503 MHz) at 298 K. Samples were dissolved in CDCl3 or d6-acetone contained in 5 mm sample tubes. Chemical shifts are given in ppm relative to internal tetramethylsilane for 1H and 13C NMR spectra and external H3PO4 for 31 P NMR spectra. Electrospray mass spectra (ES MS; positive-ion mode) were obtained with Fisons Platform II and Bruker MicroTOF (high resolution) spectrometers. Solutions in MeOH or MeCN were injected into a via a 10 mL injection loop; nitrogen was used as the drying and nebulizing gas. Chemical aids to ionization were used as required.23 Elemental analyses were performed by CMAS, Belmont, Victoria 3216, Australia. Reagents. The compounds (RCtC)2CO (R = Me3Si, Pri3Si)24 and RuCl(dppe)Cp25 were prepared by the cited methods. {(Ph3P)AuC;C}2CO (1). (a). NaOMe (1 M in MeOH, 0.54 mL, 0.54 mmol) was added to a solution of (Me3SiCtC)2CO (50 mg, 0.23 mmol) and AuCl(PPh3) (0.22 g, 0.45 mmol) in 1:1 THF (10 mL).

ARTICLE

The mixture was stirred at room temperature under N2 for 2 h and then concentrated under vacuum. The residue was dissolved in the minimum volume of CH2Cl2, MeOH (40 mL) was added, and the mixture was swirled for a few minutes. The resulting precipitate was collected, rinsed with MeOH, and dried to afford 1 (114 mg, 50%) as an off-white solid. Anal. Calcd for C51H30Au2OP2 (Mr 720): C, 49.51; H, 3.04. Found: C, 49.49; H, 3.07. IR (Nujol, cm
1): ν(CH) 3052, ν(CtC) 2106, ν(CdO) 1593, ν(CdC) 1480, 1435; other bands at 1170, 1101, 1027, 998, 745, 730, 710, 693. 1H NMR (CDCl3): δ 7.45
7.55 (30H, m). 13C NMR (CDCl3): δ 105.06 (J(CP) = 24 Hz, tCC(O)), 128.91
134.21 (Ph), 139.20 (J(CP) = 134 Hz, tCAu), 160.66 (s, CO). 31 P NMR (CDCl3): δ 40.7 (AuPPh3). ES-MS (MeOH, m/z found (calcd)): 2185.087 (2185.187), [2M + Au]+; 2011.132 (2011.210), [2M + Na]+; 1453.146 (1453.167), [M + Au(PPh3)]+; 1033.080 (1033.073), [M + K]+; 1017.103 (1017.100), [M + Na]+; 995.127 (995.118), [M + H]+; 721.168 (721.148), [Au(PPh3)2]+; also 2027, [2M + K]+; 1749, [(2M + Na)
PPh3]+; 1715, [M + Au(PPh3)2]+. (b). A solution of (Pri3SiCtC)2CO (0.10 g, 0.26 mmol) and AuCl(PPh3) (0.25 g, 0.51 mmol) in THF (10 mL) was cooled to 0 °C and [NBu4]F (1 M in THF, 0.56 mL, 0.56 mmol) was added dropwise, followed by 1 drop of water, and the solution was stirred at 0 °C for 1 h and then concentrated under vacuum. Isolation of the product as above afforded 1 (69 mg, 27%). [1,4-{Cp(dppe)Ru}2{c-COC(OMe)CHCCH}]PF6 (2). To a mixture of {(Ph3P)AuCtC}2CO (124 mg, 0.125 mmol), RuCl(dppe)Cp (150 mg, 0.250 mmol), and [NH4]PF6 (43 mg, 0.263 mmol) was added MeOH (14 mL), and the mixture was refluxed for 3.5 h, during which time the solution darkened in color. DBU (2
3 drops) was added to the reaction mixture, and after 1 h a yellow precipitate started to form. Solvent was removed and the residue purified by flash column chromatography (silica, initially CH2Cl2 and then a CH2Cl2
acetone gradient (up to 2% acetone)) to give a yellow fraction, which afforded [1,4-{Cp(dppe)Ru}2{c-COC(OMe)CHCCH}]PF6 (2; 104 mg, 60%) as a bright yellow solid. X-ray-quality crystals were grown from CH2Cl2/ hexane. Anal. Calcd for C68H63F6O2P5Ru2 (Mr(cation) 1238, mol wt 1383): C, 59.05; H, 4.59. Found: C, 58.98; H, 4.63. IR (CH2Cl2, cm
1): ν(CdC) 1573vs, 1483w, 1451s, 1435s, 1400 m, 1385s. IR (Nujol, cm
1): ν(CdC) 1567 m, 1306 w, 1262 m, 1097 m, 1015 m, ν(PF) 836 s. 1H NMR (d6-acetone): δ 2.58 (s, 3H, OMe), 2.74, 2.90 (2m, 4  CH2, 2  dppe), 4.24, 4.89 (2s, 2  5H, 2  Cp), 5.05 (s, 1H, CH), 7.01
7.71 (m, 41H, Ph + CH). 13C NMR (d6-acetone): δ 25.98
26.66 (m, CH2P), 54.78 (s, OMe), 64.66 (OC(OMe)C), 86.37, 86.92 (2s, Cp), 127.29
143.52 (m, Ph + C(2,4)), 212.88, 215.51 (2t, J(CP) = 14, 16 Hz, respectively, Ru
C). 31P NMR (d6-acetone): δ 93.0, 90.9 (2s, 2  2P, 2  Ru(dppe)Cp),
142.2 (sept, J(PF) = 705 Hz, 1P, PF6). ES-MS (MeOH, m/z): 1239, M+; 565, [Ru(dppe)Cp]+. Structure Determinations. Diffraction data were measured at 100 K using an Oxford Diffraction Xcalibur or Gemini diffractometer fitted with monochromatic Mo Kα (λ = 0.710 73 Å) (1) or Cu Kα radiation (λ = 1.541 84 Å) (2). Following analytical (1) or multiscan (2) absorption corrections and solution by direct methods, the structures were refined by full-matrix least squares on F2. Anisotropic displacement parameter forms were refined for the non-hydrogen atoms, hydrogen atom treatment following a riding model. Conventional residuals R1 and wR2 on F2 are given. Neutral atom complex scattering factors were used within the SHELXL 97 program system.26 Pertinent results are given in the figures (which show non-hydrogen atoms with 50% probability amplitude displacement ellipsoids and hydrogen atoms with arbitrary radii of 0.1 Å) and in their accompanying captions. For 2, the site occupancy of the CH2Cl2 molecule was refined to 0.589(5). Complex 1: [{(Ph3P)AuCtC}2CO]2 3 C6H6 = C82H60Au4O2P4 3 C6H6, mol wt 2067.15, monoclinic, space group P21/c, a = 17.6684(6) Å, b = 17.1866(6) Å, c = 25.4564(10) Å, β = 107.800(4)°, V = 7360.0(5) Å3, Fcalcd = 1.866 g cm
3, Z = 4, 2θmax = 60°, μ = 8.085 mm
1 (Mo Kα), 5455

dx.doi.org/10.1021/om200659t |Organometallics 2011, 30, 5452–5456

Organometallics transmission (min/max) = 0.70, crystal 0.11  0.11  0.05 mm3, 93 696 reflections measured, 21 444 unique reflections (Rint = 0.087), 16 025 reflections with I > 2σ(I), R1 (I > 2σ(I)) = 0.053, wR2 (all data) = 0.097. Complex 2: [1,4-{Cp(dppe)Ru}2{c-COC(OMe)CHCCH}]PF6 3 0.589CH2Cl2 = C68H63O2P4Ru2.F6P 3 0.589CH2Cl2, mol wt 1433.2, monoclinic, space group P21/n, a = 17.6726(4) Å, b = 19.2342(4) Å, c = 19.8112(3) Å, β = 111.625(2)°, V = 6260.2(2) Å3, Fcalcd = 1.521 g cm
3, Z = 4, 2θmax = 134°, μ = 6.11 mm
1 (Cu Kα), transmission (min/max) = 0.74, crystal 0.13  0.10  0.07 mm3, 56 740 reflections measured, 10 997 unique reflections (Rint = 0.048), 8651 reflections with I > 2σ(I), R1 (I > 2σ(I)) = 0.041, wR2 (all data) = 0.107.

’ ASSOCIATED CONTENT Supporting Information. CIF files giving full details of the structure determinations for 1 and 2. This material is available free of charge via the Internet at http://pubs.acs.org. Full details of the structure determinations (except structure factors) have also been deposited with the Cambridge Crystallographic Data Centre as CCDC 805626 (1) and 797935 (2). Copies of this information may be obtained free of charge from The Director, CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (fax, + 44 1223 336 033; e-mail, [email protected]; web, www: http://www.ccdc.cam.ac.uk).

bS

’ AUTHOR INFORMATION Corresponding Author

*Fax: + 61 8 8303 4358. E-mail: [email protected].

’ ACKNOWLEDGMENT The Australian Research Council is acknowledged for support of this work, as is Johnson Matthey plc, Reading, U.K., for a generous loan of RuCl3 3 nH2O. ’ REFERENCES (1) (a) Paul, F.; Lapinte, C. Coord. Chem. Rev. 1998, 178
180, 427. (b) Paul, F.; Lapinte, C. In Unusual Structures and Physical Properties in Organometallic Chemistry; Gielen, M., Willem, R., Wrackmeyer, B., Eds.; Wiley: London, 2002; pp 220
291. (2) Low, P. J. Dalton Trans. 2005, 2821. (3) Bruce, M. I.; Low, P. J. Adv. Organomet. Chem. 2004, 50, 179. (4) Bruce, M. I.; Low, P. J.; Costuas, K.; Halet, J.-F.; Best, S. P.; Heath, G. A. J. Am. Chem. Soc. 2000, 122, 1949. (5) Dembinski, R.; Bartik, T.; Bartik, B.; Jaeger, M.; Gladysz, J. A. J. Am. Chem. Soc. 2000, 122, 810. (6) Xi, B.; Ren, T. C. R. Chim. 2009, 12, 321. (7) (a) C6H4-1,4: Le Narvor, N.; Lapinte, C. Organometallics 1995, 14, 634. (b) C6H4-1,3: Weyland, T.; Costuas, K.; Toupet, L.; Halet, J.-F.; Lapinte, C. Organometallics 2000, 19, 4228. (c) C6H4C6H4-4,40 : Ibn Ghazala, S.; Paul, F.; Toupet, L.; Roisnel, T.; Hapiot, P.; Lapinte, C. J. Am. Chem. Soc. 2006, 128, 2463. (d) C10H6-1,4: Tanaka, Y.; ShawTaberlet, J. A.; Justaud, F.; Cador, O.; Roisnel, T.; Akita, M.; Hamon, J.-R.; Lapinte, C. Organometallics 2009, 28, 4656. (e) C14H8-9,10: de Montigny, F.; Argouarch, G.; Costuas, K.; Halet, J.-F.; Roisnel, T.; Toupet, L.; Lapinte, C. Organometallics 2005, 24, 4558. (8) Bruce, M. I.; Burgun, A.; Parker, C. R.; Skelton, B. W.; White, A. H. Unpublished work. (9) (a) Cross, R. L.; Davidson, M. F.; McLennan, A. J. J. Organomet. Chem. 1984, 265, C37. (b) Cross, R. J.; Davidson, M. F. J. Chem. Soc., Dalton Trans. 1986, 411. (10) (a) Khairul, W. M.; Fox, M. A.; Zaitseva, N. N.; Gaudio, M.; Yufit, D. S.; Skelton, B. W.; White, A. H.; Howard, J. A. K.; Bruce, M. I.;

ARTICLE

Low, P. J. Dalton Trans. 2009, 610. (b) Man, W. Y.; Bock, S.; Zaitseva, N. N.; Bruce, M. I.; Low, P. J. J. Organomet. Chem. 2011, 696, 2172. (11) Miller, F. A.; Harney, B. M. Spectrochim. Acta A 1971, 27, 1003. (12) Bruce, M. I.; Humphrey, M. G.; Snow, M. R.; Tiekink, E. R. T. J. Organomet. Chem. 1986, 314, 213. (13) Shaw, M. J.; Afridi, S. J.; Light, S. L.; Mertz, J. N.; Ripperda, S. E. Organometallics 2004, 23, 2778. (14) (a) Balaban, A. T.; Dinculescu, A. A.; Dorofeenko, G. N.; Fischer, G. W.; Koblik, A. V.; Mezheritskii, V. V.; Schroth, W. Pyrylium Salts: Synthesis, Reactions and Physical Properties; Academic: New York, 1982. (b) Farcasiu, D.; Balaban, A. T.; Bologa, U. L. Heterocycles 1994, 37, 1165. (15) (a) Caro, B.; Senechal -Tocquer, M. C.; Senechal, D.; Marrec, P.; Saillard, J.-Y.; Truiki, C.; Kahlal, S. Tetrahedron Lett. 1993, 34, 7259. (b) Salmain, M.; Malisza, K. L.; Top, S.; Jaouen, G.; Senechal-Tocquer, M. C.; Senechal, D.; Caro, B. Bioconjugate Chem. 1994, 5, 655. (c) Malisza, K. L.; Top, S.; Vaissermann, J.; Caro, B.; Senechal-Tocquer, M. C.; Senechal, D.; Saillard, J.-Y.; Triki, S.; Kahlal, S.; Britten, J. F.; McGlinchey, M. J.; Jaouen, G. Organometallics 1995, 14, 5273. (d) Caro, B.; Guen, F. R.; Senechal -Tocquer, M. C.; Prat, V.; Vaissermann, J. J. Organomet. Chem. 1997, 543, 87. (e) Salmain, M.; Caro, B.; Le GuenRobin, F.; Blais, J. C.; Jaouen, G. ChemBioChem 2004, 5, 99. (16) Ba, F.; Cabon, N.; Robin-Le Guen, F.; Le Poul, P.; Le Poul, N.; Le Mest, Y.; Golhen, S.; Caro, B. Organometallics 2008, 27, 6396. (17) Krasnikov, V. V.; Andreichikov, Yu. P.; Kholodiva, N. V.; Dorofeenko, G. N. Zh. Org. Khim. 1977, 13, 1566. (18) Shaw, M. J.; Mertz, J. Organometallics 2002, 21, 3434. (19) (a) Tully, W.; Main, L.; Nicholson, B. K. J. Organomet. Chem. 1996, 507, 103. (b) Mace, W. J.; Main, L.; Nicholson, B. K. J. Organomet. Chem. 2005, 690, 3340. (c) Prasad, N.; Main, L.; Nicholson, B. K.; McAdam, C. J. J. Organomet. Chem. 2010, 695, 1961. (20) Canziani, F.; Galimberti, F.; Garlaschelli, L.; Malatesta, M. C.; Albinati, A.; Ganazzoli, F. J. Chem. Soc., Dalton Trans. 1983, 827. (21) Barluenga, J.; Riesgo, L.; Vicente, R.; Lopez, L. A.; Tomas, M. J. Am. Chem. Soc. 2007, 129, 7772. (22) Luo, T.; Dai, M.; Zheng, S.-L.; Schreiber, S. L. Org. Lett. 2011, 13, 2834. (23) Henderson, W.; McIndoe, J. S.; Nicholson, B. K.; Dyson, P. J. J. Chem. Soc., Dalton Trans. 1998, 519. (24) Anthony, J.; Boldi, A. M.; Rubin, Y.; Hobi, M.; Gramlich, V.; Knobler, C. B.; Seiler, P.; Diederich, F. Helv. Chem. Acta 1995, 78, 13. (25) Alonso, A. G.; Reventos, L. B. J. Organomet. Chem. 1998, 338, 249. (26) SHELXL97: Sheldrick, G. M. Acta Crystallogr. 2008, A64, 112.

5456

dx.doi.org/10.1021/om200659t |Organometallics 2011, 30, 5452–5456