DALTON COMMUNICATION J. Chem. Soc., Dalton Trans., 1999, 1911–1912 1911 Control of intramolecular acetate–allenylidene coupling by spectator co-ligand �-acidity Karsten J. Harlow, Anthony F. Hill* and Thomas Welton * Department of Chemistry, Imperial College of Science Technology and Medicine, South Kensington, London, UK SW7 2AY. E-mail: a.hill@ic.ac.uk Received 15th March 1999, Accepted 7th May 1999 The reactions of [RuHX(PPh3)3] (X = Cl, O2CMe) and [MHCl(CO)(PPh3)3] (M = Ru, Os) with 1,1-diphenylprop- 2-yn-1-ol provide convenient access to alkynyl, alkenyl, propenylidene, and acetoxyallenyl complexes of divalent ruthenium and osmium, including [RuCl2(]] CHCH]] CPh2)(PPh3)2] and the complexes [Ru(C]] ] CCPh2OH)- (O2CMe)(CA)2(PPh3)2] (A = NCMe3, O), protonation (HPF6) of which provides [Ru(O2CMe)(]] C]] C]] CPh2)- (CNCMe3)2(PPh3)2]PF6 or the metallacycle [Ru{k2C,OC(]] C]] CPh2)O2CMe}(CO)2(PPh3)2]PF6, respectively.There is currently enormous interest in the chemistry of alkylidene complexes of divalent ruthenium.1 This is inspired primarily by Grubbs’ ground-breaking discovery of highly eVective and remarkably tolerant alkene metathesis catalysts of the form [RuCl2(]] CHR)(PR93)2] (R = Ph, CH]] CPh2; R9 = Ph, Cy)2 which are currently enjoying increasingly wide application in a variety of synthetically useful C–C bond-forming processes. 3 We have recently shown that [RuCl2(PPh3)3] reacts with 1,1-diphenylprop-2-yn-1-ol 1 to provide the coordinatively unsaturated allenylidene complex [RuCl2(]] C]] C]] CPh2)(PPh3) 2].4a This complex may be easily converted to [RuCl2- (]] C]] C]] CPh2)(PCy3)2] which serves as a conveniently accessible alternative to Grubbs’ catalysts for the ring-closure alkene metathesis of a,w-dienes and dienynes.4b The reactions of propargylic alcohols with metal hydride complexes however, take a diVerent course, viz.hydrometallation of the alkyne to provide g-hydroxyvinyl complexes which have been shown to be particularly prone to dehydroxylation, providing either s-butadienyl 5 or propenylidene 6,7 complexes depending, respectively, on the presence or absence of protons d to the metal.In search of alternative routes to coordinatively unsaturated alkylidenes of ruthenium and osmium, we have investigated the reactions of the complexes [MHCl(CO)(PPh3)3] (M = Ru 2a, Os 2b), [RuHCl(PPh3)3] 3, and [RuH(O2CMe)(PPh3)3] 4 with 1. The results which include convenient routes to alkenyl, alkynyl, allenylidene, propenylidene and acetoxyallenyl complexes are reported herein.The g-hydroxyvinyl complex [Ru(CH]] CHCPh2OH)Cl(CO)- (PPh3)2] 5 forms in high yield from the reaction of 2a with 1 (Scheme 1).† Treating 5 with Cl2PPh3 results in the high yield conversion to the propenylidene complex [RuCl2(]] CHCH]] CPh2)(CO)(PPh3)2] 6a.†,‡ The analogous osmium complex 6b † may be similarly obtained in 75% yield directly from 2b, 1 and Cl2PPh3. The complexes 6 may be viewed as analogues of the benzylidene complexes [MCl2(]] CHR)(CO)(PPh3)2] long since described by Roper.1a,b,9 The coordinatively unsaturated, carbonyl-free complex [RuCl2(]] CHCH]] CPh2)(PPh3)2] 7 was shown by Grubbs to result from the reaction of [RuCl2(PPh3)3] with 3,3-diphenylcyclopropene2a but required the non-trivial preparation and handling of 3,3-diphenylcyclopropene. We find that the reaction of 3 with 1 in acetonitrile followed by acid (HCl) work-up provides 7 conveniently and in high yield (83%).† The presumed g-hydroxyvinyl intermediate 8 in this sequence (Scheme 1) has not been fully characterised due to its sensitivity, however carbonylation (1 atmosphere) provides the air stable adduct [Ru(CH]] CHCPh2OH)Cl(CO)(NCMe)(PPh3)2] 9a, which is an isomer (CO trans to vinyl) of 9b (MeCN trans to vinyl) obtained from 5 and acetonitrile.The acetate complex 4 reacts with 1 via a quite diVerent sequence, to ultimately provide the alkynyl complex mer- [Ru(C]] ] CCPh2OH)(O2CMe)(PPh3)3] 10 (Scheme 2).† The mechanism presumably involves alkyne hydrometallation, as above, followed by oxidative addition of a second alkyne C–H bond to provide [RuH(C]] ] CCPh2OH)(CH]] CHCPh2OH)- (O2CMe)(PPh3)2] which undergoes reductive elimination of alkene and re-coordination of phosphine to provide 10.The facility of the proposed sequence is consistent with the increase in basicity of the acetate ligand in 4 relative to the chloride in 3, favouring the involvement of tetravalent ruthenium intermediates.The formulation of 10 rests firmly on spectroscopic and FAB-MS data with the mer stereochemistry at ruthenium following unequivocally from 13C-{1H} and 31P-{1H} NMR data.† Both the acetate chelation and the phosphine coordination in 10 are labile. Thus treating 10 with carbon monoxide (1 atmosphere, 25 8C) results in clean conversion to [Ru(C]] ] CCPh2- OH)(O2CMe)(CO)2(PPh3)2] 11. Similarly, addition of two equivalents of 1,1-dimethylethyl isocyanide leads to formation of [Ru(C]] ] CCPh2OH)(O2CMe)(CNCMe3)2(PPh3)2] 12, whilst excess isocyanide provides the cationic complex mer-[Ru(C]] ] CCPh2OH)(CNCMe3)3(PPh3)2]1 131, readily isolated as the tetrafluoborate salt [13]BF4.By analogy with the dehydroxylation of g-hydroxyvinyl ligands, the g-hydroxyalkynyl ligands in 11 and 12 are also prone to dehydroxylation although the final products diVer depending on the nature (p-acidity) of the co- Scheme 1 M Cl Cl CO PPh3 PPh3 Ph Ph Ru Cl CO PPh3 PPh3 Ph OH Ph Ru Cl CO PPh3 PPh3 Ph OH Ph MeCN Ru Cl NCMe PPh3 PPh3 Ph OH Ph MeCN Ru Cl NCMe PPh3 PPh3 Ph OH Ph OC Ru Cl Cl PPh3 PPh3 Ph Ph (i) HCºCCPh2OH 1 (ii) Cl2PPh3 1 MeCN Cl2PPh3 [RuHCl(PPh3)3] 3 1, MeCN CO HCl 5 M = Ru 6a M = Os 6b 7 8 9a 9b [MHCl(CO)(PPh3)3] M = Ru 2a M = Os 2b1912 J.Chem. Soc., Dalton Trans., 1999, 1911–1912 ligands. Thus the reaction of 12 with HPF6 provides an allenylidene complex viz.[Ru(O2CMe)(]] C]] C]] CPh2)(CNCMe3)2- (PPh3)2]PF6 ([14]PF6). Amongst the spectroscopic data for 141, the intense infrared absorption at 1970 cm21 is characteristic of the allenylidene ligand. The protonation of 11 with HPF6 however takes a diVerent course although an allenylidene complex akin to 141 is clearly involved. The product obtained is formulated as the metallacyclic complex [Ru{k2C,O-C(]] C]] CPh2)O2CMe}(CO)2(PPh3)2]- PF6 [15]PF6) on the basis of spectroscopic data.† We have recently observed the formation of a related metallacycle (A, Scheme 2) derived from the intermolecular coupling of an allenylidene ligand with dithiocarbamate,10 whilst Roper has shown that the coupling of methylene and acetate ligands provides the metallacycle B.11 Complex 151 may therefore be usefully viewed as a hybrid of A and B.The reason for the dichotomy in products arising from the protonation of 11 and 12 may be understood by considering the p-acidity of the coligands CO and CNCMe3. By far the majority of allenylidene complexes of Group 8 metals involve strong donor co-ligands coordinated trans to the allenylidene,1c a feature which may be expected to deactivate the allenylidene towards nucleophilic attack.Whilst the isocyanide ligands in 12 and 141 are only modest p-acids, the carbonyl ligand coordinated trans to the allenylidene in the carbonyl analogue of 141 may be expected to strongly activate the allenylidene towards attack by the internal acetate nucleophile.Acknowledgements We wish to thank the Engineering and Physical Sciences Research Council (U.K.) for the award of a studentship (to K. J. H.). A. F. H. gratefully acknowledges the award of a Senior Research Fellowship by The Royal Society and The Leverhulme Trust. Ruthenium salts were generously provided by Johnson Matthey Chemicals Ltd. Notes and references † Selected data for new complexes (satisfactory microanalytical and/or FAB-MS data obtained); IR (Nujol, cm21), NMR (CDCl3, 25 8C, ppm) 1H (270), 31P (109), 13C (68 MHz). 5: yield 97%. IR: 3573 (OH), 1917 (CO). NMR 1H: d 5.40 [d, 1 H, RuCH]] CH; J(HH) = 12.9 Hz], 6.94– 7.45 [m, 41 H, Ph 1 RuCH (obscured)]. 31P-{1H}: d 33.2. 13C{1H}: Scheme 2 R = CMe3. Ru O C PPh3 PPh3 PPh3 C C Ph OH Ph O C Me Ru RNC C O2CMe PPh3 PPh3 C C Ph OH Ph RNC Ru OC C O2CMPPh3 PPh3 C C Ph OH Ph OC Ru RNC C O2CMe PPh3 PPh3 C C Ph Ph RNC Ru OC C O PPh3 PPh3 C C Ph Ph OC O C Me (Ph3P)(OC)(Me2NCS2)Ru C S C C Ph Ph S C NMe2 (Ph3P)2(OC)(Ph)Ru H2 C O O C Me 10 B11 A10 HPF6 12 11 14+ 15+ 1 HPF6 CO CNR [RuH(O2CCH3)(PPh3)3] 4 d 80.0 [CPh2OH], 139.7 [RuCH]] CH], 144.6 [RuCH]] CH], 202.3 [t, CO; J(PC) = 14.3 Hz].This complex was also crystallographically characterised. 12 6a: yield 95%. IR: 1955 (CO). NMR 1H: d 8.01 [d, 1 H, Ru]] CHCH; J(HH) = 13.8], 15.93 [d, 1 H, Ru]] CH; J(HH) = 13.9 Hz]. 31P- {1H}: d 16.7. 13C-{1H}: d 146.9 [Ru]] CHCH], 154.2 []] CPh2], 199.0 [t, CO; J(PC) = 13.4], 322.1 [t, Ru=CH; J(PC) = 10.7 Hz]. 6b: yield 75%. IR 1932 (CO). NMR 1H: d 17.50 [dt, 1 H, Os]] CHCH; J(HH) = 13.5; J(PH) = 2.0 Hz] (OsCH]] CH obscured by Ph resonances). 31P-{1H}: d 28.0. 13C-{1H}: d 151.2 [Os]] CHCH], 152.4 []] CPh2], 177.6 [t, CO; J(PC) = 9.7 Hz], 278.1 [m, Os]] CH]. 7: yield 83%. NMR 1H: d 8.20 [d, 1 H, Ru]] CHCH; J(HH) = 9.9], 17.74 [dt, 1 H, Ru]] CH; J(HH) = 9.9; J(PH) = 9.6 Hz]. 31P-{1H}: d 28.9. These data correspond to those previously reported.2a 9a: yield 75%.IR: 3564 (OH), 2283 (CN), 1949 (CO). NMR 1H: d 0.82 [s, 3 H, CH3], 5.32 [d, 1 H, RuCH]] CH; J(HH) = 17.8], 7.59 [d, 1 H, RuCH; J(HH) = 18.5 Hz]. 31P-{1H}: d 29.3. 13C-{1H}: d 2.6 [CH3], 80.2 [CPh2OH], 119.6 [NC], 136.4 [t, RuCH]] CH; J(PC) = 4.3], 153.2 [t, RuCH; J(PC) = 15.1], 198.9 [t, CO; J(PC) = 10.3 Hz]. 9b: yield 86%. IR: 3564 (OH), 1944 (CO). NMR 1H: d 1.60 [s, 3 H, CH3], 5.48 [dt, 1 H, RuCH]] CH; J(HH) = 15.9; J(PH) = 2.0], 7.40 [d, 1 H, RuCH, J(HH) = 15.9 Hz]. 31P-{1H}: d 27.3. 10: yield 71%. IR: 3558 (OH), 2057(C]] ] C), 1531 (CO2). NMR 1H: d 0.92 [s, 3H, CH3]. 31P-{1H}: d 35.5 [d, 2 PA, J(PAPB) = 26.8], 50.9 [t, 1 PB, J(PAPB) = 26.8 Hz]. 13C-{1H}: d 24.3 [O2CCH3], 76.7 [CPh2OH], 110.5 [dt, RuC]] ] C; J(PaxC) ª J(PeqC) = 17.3], 118.3 [RuC]] ] C], 185.1 [CO2]. 11: yield 88%. IR: 3579, 3561 (OH), 2121(C]] ] C), 2051, 1978 (CO). NMR 1H: d 1.20 [s, 3 H, CH3]. 31P-{1H}: d 31.4. 13C-{1H}: d 22.8 [CH3], 75.0 [CPh2OH], 106.8 [t, RuC]] ] C; J(PC) = 20.0], 116.2 [t, RuC]] ] C; J(PC) = 2.4], 176.2 [CO2], 194.3 [t, CO; J(PC) = 9.2], 198.5 [t, CO; J(PC) = 11.9 Hz]. 12: yield 87%. IR: 3567 (OH), 2150 (CN), 2105 (CN), 2073 (C]] ] C), 1606 (CO2). NMR 1H: d 0.81, 0.89 [s × 2, 9 H × 2, CNC(CH3)3], 1.25 [s, 3 H, O2CCH3]. 31P-{1H}: d 38.3. 13C-{1H}: d 24.5 [O2CCH3], 29.8, 30.6 [CNC(CH3)3], 55.6, 56.1 [CNC(CH3)3], 75.1 [CPh2OH], 115.2 [RuC]] ] C], 176.3 [CO2]. [13]BF4: yield 65%. IR: 3563 (OH), 2194 (CN), 2150 (CN), 2111 (C]] ] C).NMR 1H: d 0.81 [s, 9 H, C(CH3)3], 0.93 [s, 18 H, C(CH3)3]. 31P-{1H}: d 34.8. [14]PF6: yield 79%. IR: 2184 (CN), 2148 (CN), 1970 (C]] C]] C), 1587 (CO2). NMR 1H: d 0.96 [s, 9 H, C(CH3)3], 1.08 [s, 9 H, C(CH3)3], 1.11 [s, 3 H, O2CCH3]. 31P-{1H}: d 34.3. [15]PF6: yield 88%. IR: 2071 (CO), 2003 (CO), 1598 (C]] C]] C). NMR 1H: 1.32 [s, 3H, O2CCH3]. 31P-{1H}: d 22.4. 13C-{1H}: d 18.4 [O2CCH3], 118.6 []] CPh2], 147.4 [t, RuC(OCO), J(PC) = 15.1], 183.6 [O2CCH3], 192.0 [t, CO; J(PC) = 9.7], 198.7 [t, CO; J(PC) = 11.3], 201.8 [t, RuC]] C, J(PC) = 4.9 Hz].‡ Whilst Cl2PPh3 was found to be the most convenient dehydroxylating agent,8 similar yields were obtained using anhydrous HCl, OSCl2 or PhSeCl and the complexes [Ru(CH]] CHCR2OH)Cl(CO)(PPh3)2] (CR2 = cyclo-C6H10, CMe2, C13H8), obtained from 2a and the appropriate propargylic alcohol. 1 For reviews on the chemistry of alkylidenes of Group 8 metals see (a) M. A. Gallop and W.R. Roper, Adv. Organomet. Chem., 1986, 25, 121; (b) W. R. Roper, J. Organomet. Chem., 1986, 300, 167; (c) A. F. Hill, in Comprehensive Organometallic Chemistry II, ed. E. W. Abel, F. G. A. Stone and G. Wilkinson, Pergamon, Oxford, 1995, vol. 7. 2 (a) S. T. Nguyen, R. H. Grubbs and J. W. Ziller, J. Am. Chem. Soc., 1993, 115, 9858; (b) P. Schwab, M. B. France, J. W. Ziller and R. H. Grubbs, Angew. Chem., Int. Ed. Engl., 1995, 34, 2039; (c) E. L. Dias, S. T. Nguyen and R. H. Grubbs, J.Am. Chem. Soc., 1997, 119, 3887. 3 A. Fürtsner, Top. Organomet. Chem., 1998, 1, 37. 4 (a) K. J. Harlow, A. F. Hill and J. D. E. T. Wilton-Ely, J. Chem. Soc., Dalton Trans., 1999, 285; (b) A. Fürstner, A. F. Hill, M. Liebl and J. D. E. T. Wilton-Ely, Chem. Commun., 1999, 601. 5 M. C. J. Harris and A. F. Hill, J. Organomet. Chem., 1992, 438, 209. 6 (a) M. A. Esteruelas, F. J. Lahoz, E. Oñate, L. A. Oro and B. Zeier, Organometallics, 1994, 13, 4258; (b) M. A. Esteruelas, F. J. Lahoz, E. Oñate, L. A. Oro and B. Zeier, B., ibid., 1994, 13, 1662. 7 K. J. Harlow, A. F. Hill, T. Welton, A. J. P. White and D. J. Williams, Organometallics, 1998, 17, 1916. 8 S. Anderson, D. J. Cook and A. F. Hill, J. Organomet. Chem., 1993, 463, C3. 9 G. R. Clark, K. Marsden, W. R. Roper and L. J. Wright, J. Am. Chem. Soc., 1980, 102, 6570. 10 B. Buriez, K. J. Harlow, A. F. Hill, T. Welton, A. J. P. White, D. J. Williams and J. D. E. T. Wilton-Ely, J. Organomet. Chem., 1999, 578, 264. 11 D. S. Bohle, G. R. Clark, C. E. F. Rickard, W. R. Roper, W. E. B. Shepard and L. J. Wright, J. Chem. Soc., Chem. Commun., 1987, 563; D. S. Bohle, G. R. Clark, C. E. F. Rickard, W. R. Roper and L. J. Wright, J. Organomet. Chem., 1989, 358, 411. 12 A. J. P. White and D. J. Williams, unpublished work. Communication 9/02021G