DALTON J. Chem. Soc., Dalton Trans., 1997, Pages 2113–2117 2113 Synthesis and reactivity of [Ru{HB(pz)3}{P(C6H11)3}Cl(OCH2R)] (pz = pyrazolyl, R = H or Me)† Christian Gemel, Guido Kickelbick, Roland Schmid and Karl Kirchner * Institute of Inorganic Chemistry, Technical University of Vienna, Getreidemarkt 9, A-1060 Vienna, Austria The complex [Ru{HB(pz)3}(cod)Cl] 1 (cod = cycloocta-1,5-diene) reacted with P(C6H11)3 (>1 equivalent) in boiling dimethylformamide (dmf) to give the highly air-sensitive intermediate [Ru{HB(pz)3}{P(C6H11)3}Cl(dmf)] which, on exposure to air in either ethanol or methanol as the solvent, was converted to the ruthenium(III) complexes [Ru{HB(pz)3}{P(C6H11)3}Cl(OCH2R)] (R = Me 2a or H 2b) in good yields.Complex 2b has been characterized by X-ray crystallography. Treatment of 2a or 2b with L = MeCN, pyridine, CO, P(OMe)3, or PMe3 in CH2Cl2 afforded the (diamagnetic) ruthenium(II) compounds [Ru{HB(pz)3}{P(C6H11)3}(Cl)L] 3–7. Most remarkably, 2a or 2b reacted also with terminal alkynes HC]] ] CR (R = Ph, CO2Et, Bun or SiMe3) giving the neutral vinylidene complexes [Ru{HB(pz)3}{P(C6H11)3}Cl (]] C]] CHR)] 8–11.Preliminary results of a study of the catalytic activity of 2 are also presented. Thus, 2a and 2b catalysed the dimerization of some terminal alkynes HC]] ] CR (R = Ph, CO2Et or SiMe3). In our continuing systematic studies of the chemistry of ruthenium tris(pyrazolylborate) complexes 1–5 we have recently shown that [Ru{HB(pz)3}(PPh3)Cl(dmf )] (pz = pyrazolyl, dmf = dimethylformamide) is a very usable precursor for the easy production of a variety of complexes of the types [Ru{HB- (pz)3}(PPh3)(Cl)L] and [Ru{HB(pz)3}(PPh3)Cl(]] C]] CHR)] (R = CO2Et, Bun or SiMe3).1 The method fails, however, when bulkier phosphines such as P(C6H11)3 or PPri 3 are used instead of PPh3.The reason is that the corresponding complex [Ru- {HB(pz)3}{P(C6H11)3}Cl(dmf)] is extremely air-sensitive and, in addition, dmf is highly labilized obviously due to both the greater steric demand as well as the higher basicity of P(C6H11)3 relative to PPh3.When [Ru{HB(pz)3}{P(C6H11)3}Cl(dmf)] was used in situ in the presence of an alcohol (MeOH or EtOH) the novel complexes [Ru{HB(pz)3}{P(C6H11)3}Cl(OCH2R)] (R = H or Me) were formed. In making a virtue of necessity, the complexes appear to be useful precursors for new complexes of the types [Ru{HB(pz)3}{P(C6H11)3}(Cl)L] [L = MeCN, pyridine, CO, P(OMe)3 or PMe3] and [Ru{HB(pz)3}{P(C6H11)3}- Cl(]] C]] CHR)] (R = Ph, CO2Et, SiMe3 or Bun).Results and Discussion Synthesis of [Ru{HB(pz)3}{P(C6H11)3}Cl(OCH2R)] (R = Me or H) The complexes [Ru{HB(pz)3}{P(C6H11)3Cl(OCH2R)] (R = Me 2a or H 2b) were synthesized in a one-pot reaction with [Ru{HB(pz)3}(cod)Cl] 1 (cod = cycloocta-1,5-diene) used as the starting material. This reaction appears to proceed via the highly reactive intermediate [Ru{HB(pz)3}{P(C6H11)3}- Cl(dmf)].Though the latter complex could not be isolated in pure form, the PPh3 analogue [Ru{HB(pz)3}(PPh3)Cl(dmf )] has recently been isolated and crystallographically characterized.2 When 1 is refluxed in dmf in the presence of P(C6H11)3 (>1 equivalent) and the resulting solid residue is exposed to air in ethanol or methanol as the solvent, complexes 2a and 2b are, on work-up, obtained in 65 and 49% yields (Scheme 1). It should be noted that even in the presence of P(C6H11)3 in excess † Ruthenium tris(pyrazolyl)borate complexes. Part 5.1 Non-SI unit employed: mB ª 9.27 × 10224 J T21.there was no evidence of the formation of [Ru{HB(pz)3}{P- (C6H11)3}2Cl], apparently for steric reasons. A similar observation has been made in the case of Ru(h5-C5Me5) complexes.6 Complexes 2a and 2b are thermally robust red solids which are stable to air both in the solid state and in solution. Characterization was by elemental analysis. The NMR spectra exhibited severe line broadening due to the paramagnetic nature of the complexes.The measured magnetic moment of 2b is meff = 1.83mB at 295 K, consistent with a d5 (RuIII) low-spin configuration with one unpaired electron. The molecular structure of 2b is depicted in Fig. 1 with important bond distances. The co-ordination geometry is approximately octahedral with all angles at ruthenium being between 88 and 96 Scheme 1 (i) P(C6H11)3, dmf, reflux; (ii) RCH2OH, O22114 J. Chem.Soc., Dalton Trans., 1997, Pages 2113–2117 and 175 and 1778. The three Ru–N (pz) bond lengths show only small deviations from the average distance of 2.108(2) Å, which is within the range of related ruthenium complexes.1–5,7 The Ru-O distance and the Ru-O-C(28) angle is 1.943(1) Å and 123.8(2)8, respectively. This means that there are no structural features implying unusual deviations or distortions. It should be noted that the Ru-Cl distance is only 2.370(1) Å, which is somewhat shorter than those found in many other HB(pz)3 complexes of RuII, e.g. 2.409(3) Å in [Ru{HB(pz)3}(PPh3)2Cl],8 2.401(1) Å in [Ru{HB(pz)3}(PPh3)Cl(]] C]] CHPh]1 and 2.418(2) Å in [Ru{HB(pz)3}(PPh3)Cl(CO)].9 Complexes 2a and 2b turned out to be useful reagents for the preparation of compounds of the types [Ru{HB(pz)3}- {P(C6H11)3}(Cl)L] and [Ru{HB(pz)3}{P(C6H11)3}Cl(]] C]] CHR)] as will be outlined in the following paragraphs. Reaction of [Ru{HB(pz)3}{P(C6H11)3}Cl(OCH2R)] with MeCN, pyridine, CO, P(OPh)3, PMe3 and HC]] ] CR9 (R9 = Ph, CO2Et, Bun or SiMe3) Treatment of complex 2a or 2b with L = MeCN, pyridine, CO, P(OMe)3 and PMe3 in CH2Cl2 affords the diamagnetic ruthenium(II) compounds [Ru{HB(pz)3}{P(C6H11)3}(Cl)L] 3–7 each in high yields (Scheme 2).All these compounds are thermally robust solids which are stable to air both in the solid state and in solution. Characterization was by elemental analysis, 1H and 31P-{1H} NMR spectroscopy, and in the case of 4–6 also by 13C-{1H} NMR spectroscopy, noting no unusual features. The reaction of complex 2a with L = MeCN, py, CO, P(OMe)3 and PMe3 has been monitored by 1H NMR spectroscopy showing the formation 3–7 together with 0.5 equivalent of acetaldehyde and 0.5 equivalent of ethanol according to equation (1).In the absence of kinetic data it should just 2[Ru{HB(pz)3}{P(C6H11)3}Cl(OEt)] 1 2 L æÆ 2a 2[Ru{HB(pz)3}{P(C6H11)3}(Cl)L] 1 MeCHO 1 EtOH (1) 3–7 be noted that the reaction rate seems to increase with the basicity of L.In the same way the reaction of 2b is found to release 0.5 equivalent of each formaldehyde and methanol. Overall, reaction (1) represents the recombination of two alkoxy radicals. In order to see whether a free-radical pathway operates, we treated 2a in CDCl3 with a five-fold excess of P(OMe)3 in the presence of an eight-fold excess of PriOH. Since in the 1H NMR spectrum no acetone could be detected (but a Fig. 1 Structural view of [Ru{HB(pz)3}{P(C6H11)3}Cl(OMe)] 2b.Selected bond lengths (Å) and angles (8): Ru]O 1.943(1), Ru]N(2) 2.133(2), Ru]N(4) 2.084(2), Ru]N(6) 2.109(2), Ru]Cl 2.370(1), Ru]P 2.394(1) and O]C(28) 1.370(4); C(28)]O]Ru 123.8(2), Cl]Ru]N(4) 174.7(1), N(6)]Ru]O 175.4(1) and N(2)]Ru]P 177.3(1) small amount of acetaldehyde) homolytic Ru]O bond cleavage can be ruled out. An alternative, although speculative, pathway could be initial b elimination in 2a with the ruthenium(III) hydride complex formed reacting with another molecule of 2a.Most remarkably, complex 2a (2b) reacts also with terminal alkynes HC]] ] CR9 (R9 = Ph, CO2Et, Bun or SiMe3) in CH2Cl2 giving the neutral vinylidene complexes [Ru{HB(pz)3}{P(C6- H11)3}Cl(]] C]] CHR9)] 8–11 according to equation (1) (Scheme 2) in high yields, except for 8. All of these solids are pale red, air stable in the solid state, but decompose slowly in aerobic solutions to the carbonyl complex [Ru{HB(pz)3}{P(C6H11)3}- Cl(CO)] 5, adding to the known cases of the oxidation of ruthenium(II) vinylidene complexes by dioxygen.10 In another type of conversion, complex 11 reacts with MeOH as the solvent at room temperature to give the alkoxycarbene complex [Ru{HB(pz)3}{P(C6H11)3}Cl{]] C(OMe)Me}] 12 in almost quantitative yield.All other vinylidene complexes are stable in this solvent. All the vinylidene complexes have been characterized by 1H and 31P-{1H} NMR and, in the case of sufficient stability as for 10 and 11, 13C-{1H} NMR spectra.In the latter there are characteristic low-field resonances at d 361.0 and 340.2 assignable to the a-carbon of the vinylidene moiety. The Cb hydrogen atom gives rise to a resonance in the range from d 4.06 to 3.71 (1 H). Finally, the resonances of the HB(pz)3 and P(C6H11)3 ligands are in the expected ranges. Catalytic dimerization of terminal acetylenes Reaction of complex 2b with an excess of HC]] ] CPh in toluene at reflux for 20 h results in the formation (about 50% conversion) of the head-to-head dimers (E)-1,4-diphenylbut-1-en-3- yne (I) and the Z isomer (II) in 67 and 33% yields, respectively (Table 1).The selectivity is found to vary with the alkyne substituent as follows. For R = CO2Et the reaction is selective giving predominantly the head-to-head dimer I and only small amounts of the 1,3,5-tricarboxylic acid ester III, while for R = SiMe3 the regioselectivity is reversed with no I but 100% of II.For R = Bun, no coupling reaction took place at all. Scheme 2 (i) L; (ii) HC]] ] CR9J. Chem. Soc., Dalton Trans., 1997, Pages 2113–2117 2115 The mechanism of the catalytic dimerization of terminal alkynes can only be speculated upon at present. From our preceding paper it is reasonable to suggest that the reaction is initiated by the neutral vinylidene complex [Ru{HB(pz)3}- {P(C6H11)3}Cl(]] C]] CHR)] formed as an intermediate with subsequent HCl elimination affording a 16e alkynyl catalyst.2 Neutral vinylidene complexes have been shown recently to undergo 1,3-HCl eliminations upon treatment with base to give 16e alkynyl intermediates which could be trapped in the presence of potential ligands such as CO, pyridine or MeCN.11 Similar intermediates have been suggested to be involved in the coupling reaction of terminal acetylenes catalysed by [Ru{HB- (pz)3}(PPh3)2Cl] and [Ru(h5-C5Me5)(PR3)H3] (R = Ph, Me or C6H11).2,12 Experimental General information All reactions were performed under an inert atmosphere of purified argon using Schlenk techniques.All chemicals were standard reagent grade used without further purification. The solvents were purified according to standard procedures. The deuteriated solvents (Aldrich) were dried over 4 Å molecular sieves. The complex [Ru{HB(pz)3}(cod)Cl] was prepared according to the literature.5 Proton, 13C-{1H} and 31P-{1H} NMR spectra were recorded on a Bruker AC-250 spectrometer operating at 250.13, 62.86 and 101.26 MHz, respectively, and were referenced to SiMe4 and to H3PO4 (85%).Microanalyses were by Microanalytical Laboratories, University of Vienna. Syntheses [Ru{HB(pz)3}{P(C6H11)3}Cl(OEt)] 2a. A solution of complex 1 (465 mg, 1.02 mmol) in dmf (8 cm3) was treated with P(C6H11)3 (285 mg, 1.02 mmol) and the mixture heated under reflux for 2 h. After removal of the solvent, ethanol was added and air was admitted to the solution, whereupon an immediate change from yellow to dark red occurred.After 15 min a red precipitate was formed, which was collected on a glass frit, washed with diethyl ether, and dried under vacuum. Yield: 445 mg (65%) (Found: C, 51.25; H, 7.3; N, 12.25. C29H48BClN6- OPRu requires C, 51.6; H, 7.15; N, 12.45%). [Ru{HB(pz)3}{P(C6H11)3}Cl(OMe)] 2b. This complex was synthesized analogously to 2a using methanol instead of ethanol as the solvent. Yield: 49% (Found: C, 50.75; H, 7.1; N, Table 1 Conversion and product distribution of the catalytic dimerization of terminal alkynes Product (%) % Catalyst R I II III Conversion 2b 2a 2b 2a Ph CO2Et SiMe3 Bun 67 91 33 100 9 50 44 47 0 12.6.C28H46BClN6OPRu requires C, 50.9; H, 7.0; N, 12.7%). meff = 1.83mB (295 K). [Ru{HB(pz)3}{P(C6H11)3}Cl(MeCN)] 3. A solution of complex 2a (70 mg, 0.104 mmol) in benzene (5 cm3) was treated with MeCN (0.1 cm3, 1.91 mmol) and the mixture stirred at 70 8C for 5 h. After removal of the solvent the residue was redissolved in acetone and the product precipitated by addition of diethyl ether and light petroleum (b.p. 40–70 8C). It was collected on a glass frit, washed with light petroleum and dried under vacuum. Yield: 51 mg (73%) (Found: C, 52.1; H, 7.05; N, 14.25. C29H46BClN7PRu requires C, 51.9; H, 6.9; N, 14.6%). NMR (C6D6, 20 8C): dH 8.30 (m, 2 H), 7.71 (d, 2 H, J = 2.5), 7.63 (d, 1 H, J = 1.6), 7.57 (d, 1 H, J = 2.5 Hz), 6.15–6.00 (m, 3 H), 2.57 (m, 3 H), 2.10–1.60 (m, 30 H) and 1.53 (s, 3 H, CH3CN); dP 38.5.[Ru{HB(pz)3}{P(C6H11)3}Cl(py)] 4. A solution of complex 2a (70 mg, 0.104 mmol) in CH2Cl2 (5 cm3) was treated with pyridine (py) (0.1 cm3, 1.24 mmol) and stirred at room temperature for 12 h. After removal of the solvent the residue was redissolved in CH2Cl2 and the product precipitated by addition of diethyl ether and light petroleum. It was collected on a glass frit, washed with light petroleum and dried under vacuum. Yield: 60 mg (81%) (Found: C, 54.05; H, 7.05; N, 13.6.C32H48BClN7PRu requires C, 54.2; H, 6.8; N, 13.85%). NMR (CDCl3, 20 8C): dH 9.7 (br s, 2 H, py), 8.07 (s, 1 H), 7.85 (s, 1 H), 7.52 (s, 1 H), 7.49 (m, 1 H, py), 7.21 (s, 1 H), 6.98 (s, 1 H), 6.90 (br s, 2 H, py), 6.24 (s, 1 H), 6.19 (s, 1 H), 6.04 (s, 1 H) and 2.23–1.05 (m, 33 H); dC 148.4, 146.8, 142.3, 137.3, 136.2, 134.5, 134.4, 128.9, 128.5, 128.1, 123.4, 36.4 (br s), 30.0 (br s), 28.9 and 27.08; dP 34.5. [Ru{HB(pz)3}{P(C6H11)3}Cl(CO)] 5.A solution of complex 2a (70 mg, 0.104 mmol) in CH2Cl2 (5 cm3) was purged with CO for 5 min and then stirred for 48 h. After removal of the solvent the residue was redissolved in CH2Cl2 and the product precipitated by addition of diethyl ether and light petroleum. It was collected on a glass-frit, washed with light petroleum and dried under vacuum. Yield: 52 mg (76%) (Found: C, 50.95; H, 6.65; N, 12.55. C28H43BClN6OPRu requires C, 51.1; H, 6.6; N, 12.75%). NMR (CDCl3, 20 8C): dH 8.11 (s, 1 H), 7.89 (s, 1 H), 7.77 (s, 1 H), 7.72 (s, 1 H), 7.49 (s, 1 H), 7.42 (s, 1 H), 7.26 (s, 1 H), 6.27 (s, 1 H), 6.19 (s, 1 H), 6.13 (s, 1 H), 2.45–2.10 (m, 3 H), 1.93–1.45 (m, 21 H) and 1.42–1.0 (m, 9 H); dC 205.9 (d, J = 14.5), 146.4, 144.8, 143.1, 137.1, 136.6, 134.5, 106.9, 106.0, 105.7, 34.8 (d, J = 19.3), 29.6, 29.4 and 28.1 (d, J = 9.6 Hz); dP 35.3.[Ru{HB(pz)3}{P(C6H11)3}Cl{P(OMe)3}] 6. This complex was prepared analogously to 4 using P(OMe)3 instead of pyridine.Yield: 84% (Found: C, 47.6; H, 7.1; N, 10.85. C30H52BClN6- O3P2Ru requires C, 47.8; H, 6.95; N, 11.15%). NMR (CDCl3, 20 8C): dH 8.14 (d, 1 H, J = 1.7), 7.92 (d, 1 H, J = 2.1), 7.84 (d, 1 H, J = 2.1), 7.71 (d, 1 H, J = 2.44), 7.68 (s, 1 H), 7.49 (d, 1 H, J = 2.44), 6.21 (m, 1 H), 6.05 (m, 2 H), 3.39 (d, 9 H, J = 10.1), 2.46 (m, 3 H) and 1.93–1.05 (m, 30 H); dC 150.1, 145.5 (d, J = 3.8), 145.2, 137.8, 135.4 (d, J = 2.9), 134.7, 106.3 (d, J = 3.8), 105.7 (d, J = 1.9), 104.9, 52.3 (d, J = 7.2), 38.0 (m), 29.6 (br s), 29.1 (d, J = 8.6) and 27.3; dP 146.9 (d, J = 50.9) and 28.7 (d, J = 50.9 Hz).[Ru{HB(pz)3}{P(C6H11)3}Cl(PMe3)] 7. This complex was prepared analogously to 4 using PMe3 instead of pyridine. Yield: 59% (Found: C, 52.85; H, 7.55; N, 11.75. C30H52- BClN6P2Ru requires C, 51.05; H, 7.4; N, 11.9%). NMR (CDCl3, 20 8C): dH 8.02 (d, 1 H, J = 1.9), 7.81 (d, 1 H, J = 1.9), 7.68 (br s, 1 H), 7.65 (d, 1 H, J = 2.6), 7.50 (d, 1 H, J = 2.2), 7.19 (s, 1 H), 6.17 (m, 1 H), 6.05 (m, 2 H), 2.28 (m, 3 H), 2.0–1.0 (m, 30 H) and2116 J.Chem. Soc., Dalton Trans., 1997, Pages 2113–2117 1.33 (d, 9 H, J = 6.3); dP 33.4 (d, J = 31.1) and 6.2 (d, J = 31.1 Hz). [Ru{HB(pz)3}{P(C6H11)3}Cl(]] C]] CHPh)] 8. A 5 mm NMR tube was charged with a solution of complex 2a (20 mg, 0.0296 mmol) in CDCl3 (0.5 cm3) and was capped with a septum. The compound HC]] ] CPh (10 ml, 0.089 mmol) was added by syringe and the sample was transferred to a NMR probe.Proton and 31P-{1H} NMR spectra were immediately recorded showing the slow but quantitative formation of 8. All attempts to isolate this complex failed. NMR (CDCl3, 20 8C): dH 8.25 (d, 1 H, J = 2.2), 7.83 (d, 2 H, J = 2.2), 7.78 (d, 1 H, J = 2.6), 7.41 (d, 1 H, J = 1.7), 7.3 (d, 1 H, J = 1.7), 7.14 (m, 3 H), 6.94 (m, 2 H), 6.35 (m, 1 H), 6.23 (m, 1 H), 6.02 (m, 1 H), 5.01 (d, 1 H, J = 3.5 Hz), 2.37 (m, 3 H) and 2.0–0.7 (m, 30 H); dP 30.3. [Ru{HB(pz)3}{P(C6H11)3}Cl(]] C]] CHCO2Et)] 9.This complex was prepared analogously to 4 using HC]] ] CCO2Et instead of pyridine. Yield: 79% (Found: C, 52.6; H, 7.0; N, 11.35. C32H49BClN6O2PRu requires C, 52.8; H, 6.8; N, 11.55%). NMR (C6D6, 20 8C): dH 8.48 (d, 1 H, J = 2.2), 8.18 (d, 1 H, J = 2.2), 8.04 (d, 1 H, J = 2.2), 7.62 (d, 1 H, J = 2.2), 7.50 (d, 1 H, J = 2.5), 7.27 (s, 1 H), 6.10 (m, 1 H), 5.95 (m, 1 H), 5.81 (m, 1 H), 5.18 (d, 1 H, J = 3.6), 4.07 (q, 1 H, J = 7.1), 4.06 (q, 1 H, J = 7.0), 2.62 (m, 3 H), 2.1–1.1 (m, 30 H) and 1.0 (t, 3 H, J = 7.1 Hz); dP 29.5.[Ru{HB(pz)3}{P(C6H11)3}Cl(]] C]] CHBun)] 10. This complex was prepared analogously to 4 using hex-1-yne instead of pyridine. Yield: 87% (Found: C, 55.45; H, 7.2; N, 12.15. C33H53- BClN6PRu requires C, 55.65; H, 7.5; N, 11.8%). NMR (CDCl3, 20 8C): dH 8.14 (d, 1 H, J = 2.1), 7.79 (d, 1 H, J = 2.5), 7.76 (d, 1 H, J = 2.9), 7.69 (d, 1 H, J = 2.9), 7.43 (d, 1 H, J = 2.9), 7.41 (d, 1 H, J = 2.9), 6.27 (m, 1 H), 6.15 (m, 1 H), 6.06 (m, 1 H), 4.06 (dt, 1 H, J = 3.6, 8.0), 2.37 (dt, 1 H, J = 13.8, J = 8.0), 2.25–2.05 (m, 3 H), 2.0–1.4 (m, 21 H), 1.4–1.0 (m, 14 H) and 0.95–0.65 (m, 4 H); dC 361.0 (d, J = 16.9), 146.4, 145.1, 143.3, 137.5, 136.6, 134.5, 108.6, 106.6, 106.2, 105.8, 35.7, 35.4, 35.0, 29.8 (d, J = 7.2), 28.5 (d, J = 8.8 Hz), 27.0, 22.7, 18.4 and 14.4; dP 33.9.[Ru{HB(pz)3}{P(C6H11)3}Cl(]] C]] CHSiMe3)] 11. This complex was prepared analogously to 4 using HC]] ] CSiMe3 instead of pyridine.Yield: 76% (Found: C, 52.65; H, 7.4; N, 11.4. C32H53BClN6PRuSi requires C, 52.8; H, 7.35; N, 11.5%). NMR (CDCl3, 20 8C): dH 8.10 (d, 1 H, J = 2.0), 8.0 (d, 1 H, J = 2.0), 7.72 (d, 1 H, J = 2.0), 7.70 (d, 1 H, J = 2.8), 7.67 (d, 1 H, J = 2.4), 7.43 (d, 1 H, J = 2.4), 6.22 (m, 1 H), 6.18 (m, 1 H), 6.08 (m, 1 H), 3.71 (d, 1 H, J = 3.6), 2.0–1.0 (m, 33 H) and 20.27 (s, 9 H); dC 340.2 (d, J = 15.3), 146.6, 144.6, 143.4, 137.3, 136.7, 134.7, 106.6, 106.0, 105.9, 94.9, 35.5 (d, J = 19.5), 29.9, 28.5 (d, J = 10.2 Hz), 27.1 and 1.2; dP 33.9.[Ru{HB(pz)3}{P(C6H11)3}Cl{]] C(OMe)Me}] 12. A solution of complex 11 (68 mg, 0.093 mmol) in MeOH (5 cm3) was stirred at room temperature for 15 h. The product was obtained on addition of diethyl ether and light petroleum. Yield: 53 mg (83%) (Found: C, 52.25; H, 7.3; N, 12.05. C30H49BClN6OPRu requires C, 52.35; H, 7.2; N, 12.2%). NMR (CDCl3, 20 8C): dH 8.21 (d, 1 H, J = 2.1), 7.73 (d, 1 H, J = 2.4), 7.71 (d, 1 H, J = 2.4), 7.53 (d, 1 H, J = 2.7), 7.25 (d, 1 H, J = 1.7), 6.88 (d, 1 H, J = 2.4), 6.25 (m, 1 H), 6.10 (m, 1 H), 6.03 (m, 1 H), 4.07 (s, 3 H), 2.51 (s, 3 H) and 2.1–0.7 (m, 33 H); dC 318.2 (d, J = 13.7), 146.3, 145.9, 142.7, 137.0, 135.4, 134.4, 106.4, 106.1, 105.8, 59.7, 40.2, 35.4 (d, J = 14.5), 29.8, 28.8 (d, J = 7.2 Hz) and 27.7; dP 40.1.Catalytic dimerization of HC]] ] CR (R = Ph, CO2Et, Bun or SiMe3) In a typical procedure, the alkyne (0.3 mmol) was added to a suspension of either complex 2a or 2b (2 mol %) in toluene (5 cm3) and the sealed Schlenk tube was heated in an oil-bath for 20 h at 111 8C.After that time the reaction mixture was evaporated to dryness under vacuum and the coupling products were extracted with hexane. The solvent was again removed under vacuum affording isomeric mixtures of coupling products. The product distribution was determined by 1H NMR spectroscopy. Crystallography Crystal data and experimental details are given in Table 2.X-Ray data for complex 2b were collected on a Siemens Smart CCD area-detector diffractometer, with graphite-monochromated Mo-Ka radiation, (l 0.710 73 Å), a nominal crystalto- detector distance of 3.85 cm, and 0.38 w-scan frames were used. Corrections for Lorentz-polarization effects, crystal decay, and absorption (SADABS)13 were applied. The structures were solved by direct methods.14 All non-hydrogen atoms were refined anisotropically, and hydrogen atoms were included in idealized positions.15 The structures were refined against F2.Atomic coordinates, thermal parameters, and bond lengths and angles have been deposited at the Cambridge Crystallographic Data Centre (CCDC). See Instructions for Authors, J. Chem. Soc., Dalton Trans., 1997, Issue 1. Any request to the CCDC for this material should quote the full literature citation and the reference number 186/504. Acknowledgements Financial support by the Fonds zur Förderung der wissenschaftlichen Forschung is gratefully acknowledged (Project No. 11896). Thanks are due to Professor Scot Wherland and Dr. John Coddington (Washington State University, USA) for performing the magnetic susceptibility measurements. References 1 Part 4, C. Slugovc, K. Mereiter, E. Zobetz, R. Schmid and K. Kirchner, Organometallics, 1996, 15, 5275. 2 C. Slugovc, V. N. Sapunov, P. Wiede, K. Mereiter, R. Schmid and K. Kirchner, unpublished work. Table 2 Crystallographic data for [Ru{HB(pz)3}{P(C6H11)3}Cl(OMe)] 2b Formula M Crystal size/mm Space group Crystal system a/Å b/Å c/Å a/8 b/8 g/8 U/Å3 F(000) Z Dc/g cm23 T/K m(Mo-Ka)/mm21 qmax/8 hkl Index ranges No.reflections measured No. unique reflections No. reflections F > 4s(F) No. parameters R(F)[F > 4s(F)] (all data) wR(F2) (all data) Minimum, maximum Fourier-difference peaks/e Å23 C28H46BClN6OPRu 661.01 0.32 × 0.25 × 0.21 P1� Triclinic 9.638(1) 10.715(1) 16.335(1) 108.17(1) 92.37(1) 103.83(1) 1 544.1(1) 690 2 1.422 297 0.678 30.5 213 to 11, 210 to 15, 223 to 23 13 407 9290 9289 350 0.038 0.063 0.105 20.69, 0.53 R(F) = S Fo| 2 |Fc /S|Fo|, wR(F2) = [Sw(Fo 2 2 Fc 2)2/Sw(Fo 2)2]� �� , w = 1/ [s2(Fo 2) 1 (0.0464P)2 1 0.27P] where P = (Fo 2 1 2Fc 2)/3.J. Chem.Soc., Dalton Trans., 1997, Pages 2113–2117 2117 3 G. Trimmel, C. Slugovc, P. Wiede, K. Mereiter, V. N. Sapunov, R. Schmid and K. Kirchner, Inorg. Chem., 1997, 36, 1076. 4 C. Gemel, P. Wiede, K. Mereiter, V. N. Sapunov, R. Schmid and K. Kirchner, J. Chem. Soc., Dalton Trans., 1996, 4071. 5 G. Gemel, G. Trimmel, C. Slugovc, K. Mereiter, S. Kremel, R. Schmid and K. Kirchner, Organometallics, 1996, 15, 3998. 6 B. K. Campion, R. H. Heyn and T. D. Tilley, J. Chem. Soc., Chem. Commun., 1988, 278. 7 N. W. Alcock, A. F. Hill and R. B. Melling, Organometallics, 1991, 10, 3898; A. F. Hill, J. Organomet. Chem., 1990, 395, C35; M. M. deV. Steyn, E. S. Singleton and D. C. Liles, J. Chem. Soc., Dalton Trans., 1990, 2991; A. M. McNair, D. C. Boyd and K. R. Mann, Organometallics, 1986, 5, 303. 8 N. W. Alcock, I. D. Burns, K. S. Claire and A. F. Hill, Inorg. Chem., 1992, 31, 2906. 9 N.-Y. Sun and S. J. Simpson, J. Organomet. Chem., 1992, 434, 341. 10 C. Bianchini, P. Innocenti, M. Peruzzini, A. Romerosa and F. Zanobini, Organometallics, 1996, 15, 272. 11 M. I. Bruce, B. C. Hall, N. N. Zaitseva, B. W. Skelton and A. H. White, J. Organomet. Chem., 1996, 522, 307. 12 C. S. Yi and N. Liu, Organometallics, 1996, 15, 3968. 13 G. M. Sheldrick, SADABS, Program for empirical absorption correction of Siemens SMART CCD detector data, University of Göttingen, 1996. 14 G. M. Sheldrick, SHELXS 86, Program for the Solution of Crystal Structures, University of Göttingen, 1986. 15 G. M. Sheldrick, SHELXL 93, Program for Crystal Structure Refinement, University of Göttingen, 1993. Received 27th January 1997; Paper