Influence of Chloride versus Hydride on HH Bonding and Acidity of the Trans Dihydrogen Ligand in the Complexes trans-[Ru(H2)X(PR2CH2CH2PR2)2]+, X = Cl, H, R = Ph, Et. Crystal Structure Determinations of [RuCl(dppe)2]PF6 and trans-[Ru(H2)Cl(dppe)

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Influence of Chloride versus Hydride on HH Bonding and Acidity of the Trans Dihydrogen Ligand in the Complexes trans-[Ru(H2)X(PR2CH2CH2PR2)2]+, X = Cl, H, R = Ph, Et. Crystal Structure Determinations of [RuCl(dppe)2]PF6 and trans-[Ru(H2)Cl(dppe)2]PF6
  6278 Inorg. Chem. 1994,33, 6278-6288 Influence of Chloride versus Hydride on H-H Bonding and Acidity of the Trans Dihydrogen Ligand in the Complexes trans-[Ru(Hz)X(PR2CH2CHflR&]+, X = C1, H, R = Ph, Et. Crystal Structure Determinations of [RuCl(dppe)z]PF6 and trans- [ Ru(Hz)Cl(dppe)z]PF6 Bain Chin, Alan J. Lough, Robert H. Morris,' Caroline T. Schweitzer, and Cinzia D'Agostino Department of Chemistry and Scarborough Campus, University of Toronto, Toronto, Ontario M5S 1A1, Canada Received April 22, 1994@ The complex [RuCl(dppe)z]PF, 1, dppe = Ph2PCH2CH2PPh2, is prepared by reacting cis-RuClz(dppe)2 with NaPF6. It has a distorted trigonal bipyramidal geometry with a Ru(P)2Cl Y shaped equatorial plane. In weakly coordinating solvents it is mainly five-coordinate. Under FAB MS conditions it is ionized to [RuCl(PFs)(dppe)2]+. It reacts with C1- or L = CO, CH3CN to give complexes cis-RuCl~(dppe)2 or cis-[Ru(Cl)(L)(dppe)2]PF6, respectively. Dihydrogen reacts with 1 o give trans-[Ru(H2)Cl(dppe)2]PFa, 2a. The reaction of HA, A = BF4 or PF6, with complexes truns-RuH(Cl)(dppe)2 or trans-RuHCl(depe)z, depe = PEt2CH2CH2PEt2, gives dihydrogen complexes truns-[Ru(H2)Cl(dppe)2]A, 2a, and trans-[Ru(H2)Cl(depe)2]A, 2b. The H-H distances in complexes 2 are longer than those found in analogous complexes trans-[Ru(H2)H(diphos)2lf 3 probably because of the x effect of the C1-. Associated with the H-H lengthening is a dramatic reduction in the pKa of 2a (6) vs 3a (15). An electron-rich trihydride complex [Ru(H)3(dppf)2]+ (4), dppf = 1,l -bis(diphenylphosphino)ferrocene, with no H-H bond is found to be, paradoxically, the most acidic (pKa Z 4). Bond dissociation energies calculated for complexes 2a, 3a, and 4 from PKa and electrochemical data also suggest that the amount of the H-H bonding has a major influence on the acidity of the complexes. Complex 2a in CH2C12 under Ar appears to slowly lose HC1 at 233 K; it reacts with CO at 273 K to give HCl and trans-[Ru(CO)H(dppe)z]+ and with H2 in the presence of Na+ to give 3a. Complex 1 crystallizes in the space group P211c with a = 12.427(2) A, b = 15.565(3) A, c = 26.759(5) A, p = 95.94(3) , v 5148.1 A3, and Dc cd = 1.391 g cm-3 for z = 4. Least squares refinement of the model based on 4383 observed reflections (F > 6.0a(F)) converged to a final RF = 5.4%. Complex 2a crystallizes in the space group P21111 with u = 15.315(1) A, b = 17.479(1) A, c = 18.608(1) A, /3 = 101.79(1) , V = 4875.9(7) A3, and Dcdcd = 1.472 g cm-3 for Z = 4. Least squares refinement of the model based on 9208 observed reflections (F > 4.0a(F)) converged to a final RF = 5.1%. There is electron density associated with the H2 ligand trans to the chloride in octahedral 2a. Introduction The nature of the ancillary ligands in a dihydrogen complex can have a dramatic influence on the structure and reactivity of the dihydrogen ligand. We have determined how the structure and acidity of dihydrogen complexes truns-[M(Hz)H(PR2CHz- CH2PR2)2]+ change with a systematic change in cis bidentate phosphine ligands; when the R substituents are changed from p-CF3C6b to p-MeOCa the pKa of the ruthenium dihydrogen complex changes from 9 to 16 while the H-H bond lengthens only slightly.' Other variations in the cis ligands, L, in the complexes [Ru(H2)H(L)4]+, have been made by several research group^^-^^ and the effects of these variations on the spectro- scopic and H atom exchange properties of these complexes have @ Abstract published in Advance ACS Abstracts, November 1, 1994. (1) Cappellani, E. P.; Drouin, S. D.; Jia, G.; Maltby, P. A,; Moms, R. H.; Schweitzer, C. T. J. Am. Chem. SOC. 1994, 116, 3375-3388. (2) Ashworth, T. V.; Singleton, E. J. Chem. SOC., Chem. Commun. 1976, 705-706. (3) Amendola, P.; Antoniutti, S.; Albertin, G.; Bordignon, E. Inorg. Chem. 1990, 29, 318-324. (4) Tsukahara, T.; Kawano, H.; Ishii, Y.; Takahashi, T.; Saburi, M.; Uchida, Y.; Akutagawa, S. Chem. Lett. 1988, 2055-2058. 5) Ogasawara, M.; Aoyagi, K.; Saburi, M. Organomerallics 1993, 12, 3393-3395. (6) Saburi, M.; Aoyagi, K.; Kodama, T.; Takahashi, T.; Uchida, Y.; Kozawa, K.; Uchida, T. Chem. Lett. 1990, 1909-1912. (7) (a) Mezzetti, A.; Del Zotto, A.; Rigo, P.; Farnetti, E. J. Chem. SOC., Dalton Trans. 1991,1525-1530. (b) Mezzetti, A,; Del Zotto, A.; Ego, P.; Pahor, N. B. Ibid. 1989, 1045-1052. (c) Ibid. 1990, 2515-2520. been reviewed.* Li and TaubegJo have described how the spectroscopic properties of the complexes trans-[Os H *D)X- (en)# and trans-[Os(H .D)X(NH3)4]+ l1 change substantially as the trans ligand is varied; J(H,D) decreases as X = I > Br > C1?b Neutral ligands trans to the H**D igand in these osmium complexes also change J(H,D).9 There is evidence that the isomer of Jr(H**H)(H)C12(PiPr3)2 ith H2 trans to C1 is more stable with respect to H2 loss than the one with H2 trans to H.12 We report here the preparation of the complexes trans-[Ru- (H2)Cl(dppe)2]+ (2a)13 and [Ru(H2)Cl(depe)z]' (2b)13 and the characterization of their physical properties in order to compare the effect of C1 versus hydride on the ligand trans to H2. A communication described how these complexes act as interme- diates in the synthesis of complexes [Ru(Hz)HL?]+ and RuH2L2 (8) Jessop, P. G.; Moms, R. H. Coord. Chem. Rev. 1992,121, 155-284. (9) (a) Li, Z.; Taube, H. J. Am. Chem. SOC. 1991, 113, 8946-8947. (b) Hasegawa, T.; Li, Z.; Parkin, S.; Hope, H.; McMullan, R. K.; Koetzle, T. F.; Taube, H. J. Am. Chem. SOC. 1994, 116, 4352-4356. (10) Li, Z.; Taube, H. Science 1992, 256, 210-213. (1 1) The H- *D notation signifies the probable presence of an elongated ('1.0 A) and probably slow-spinning HD ligand with J(H,D) < 25 Hz see ref 8 for further details). (12) Albinati, A.; Bakhmutov, V. I.; Caulton, K. G.; Clot, E.; Eckert, J.; Eisenstein, 0.; usev, D. G.; G~shin, . V.; Hauger, B. E.; Klooster, W. T.; Koetzle, T. F.; McMullan, R. K.; O'Loughlin, T. J.; Pelissier, M.; Ricci, R. S.; Sigalas, M. P.; Vymenits, A. B. J. Am. Chem. SOC. (13) Ligand abbreviations: PR~CHZCHZPRZ, = phenyl (dppe), ethyl 1993, 115 7300-7312. (depe), cyclohexyl (dcype). 0020-166919411333-6278$04.50/0 1994 American Chemical Society  6280 Inorganic Chemistry, Vol. 33, No. 26, 994 Chin et al. PP l'~'*I~~'-l '- '~' '' ~ 1 ~'1 65 60 55 50 45 40 35 30 Figure 2. Isotropic peaks of the cation of [Ru(Hz)cl(dppe)z]PF6 n the CP MAS 31P NMR spectrum. 3'P NMR (THF): 6 51.5 (s), -144 (sept, J(P,F) = 711 Hz). CP MAS 31P NMR (120 MHz): 6 59.0 (br d, J(P,P) = 254 Hz), 56.1 (br d, J(P,P) = 229 Hz), 51.7 (br d, J(P,P) = 269 Hz), 43.3 (br d, J(P,P) = 239 Hz), -142 (sept, J(P,F) = 700 Hz); see Figure 2 for the isotropic peaks of the cation. cis-[Ru(CH3CN)cl(dppe)~]PF6. ne drop of CH3CN was added to a CHzClz solution (5 mL) of 2a (90.2 mg) with stirring to give a light yellow solution of the product (quantitative conversion by 31P NMR). Addition of acetone caused the precipitation of yellow crystals. FAB MS: only peaks due to lPF.5' and 1+ were observed (see above). IR (CHzCl2): 2306 cm-', v(CN). 31P NMR (CHzClZ): 6 59.6 (m), 42.9 (m). Observation of cis-[Ru(Co)cl(dppe)2]PF6. A CHzClz solution of 1 was exposed to 1 atm of CO with stirring. The solution immediately turned from red to colorless with quantitative conversion to the product according to the 31P MR spectrum. FAB MS: calcd for C53H~o- C10P4102R~, 61; obsd, 961 (M'), 898 (M+ - 2H Cl). (CHZClz): ABCD multiplets at 45.9, 38.8, 51.5, 24.6 ppm with JAB 256, JAC 18.9, Jm 18.9, JBC 10.5, JBD 9.4, JCD 25.9 Hz. trans-[Ru(H2)Cl(depe)#X- = BF4-, PFs- (2b). These were prepared by use of method 1 for the synthesis of 1. Under Ar as a solid, this compound slowly tumed irreversibly from white to green. FAB MS: calcd for CZOH~OC~P~~~~RU, 51; obsd, 549 (Mf - H), 515 (M+ H Cl). 'H NMR (acetone-&, 200 MHz): 6 2.4 and 2.1 (2 m, PCH2CH2P), 1.9 (m, PCH2CH3), 1.1 (m, PCHzCHj), -14.2 (quint, Observation of truns-[Ru(HD)Cl(dppe)~]PF6. When trans-[Ru- (Hz)Cl(dppe)~]PF6 as dissolved in acetone-d6, changes were observed in the shape of the H2 signal in the 'H NMR (200 MHz) due to intermolecular H/D exchange with the acetone-& The 'J(HD) coupling value for trans-[Ru(HD)Cl(dppe)~]PF6 as found to be 25.9 Hz by simulation of and comparison to the observed spectra. Observation of hans-[Ru(HD)Cl(depe)2]BF4. Method 1. After leaving a solution of trans-[Ru(H~)Cl(depe)2]BF4 n acetone-d6 for a 24 h period, by IH NMR it was found that some trans-[Ru(HD)Cl- (depe)z]BF4 had formed. Method 2. Under 1 atm of Ar, RuHCl(depe)z (0.020 g, 0.034 "01)was suspended in diethyl ether (3 mL) and DzO 0.043 mL, 1.7 01). With vigorous stirring, 2 drops (excess) HBF4.EtzO were added resulting in the immediate formation of a white precipitate. After allowing the solid to settle, the supernatant liquid was decanted and the precipitate was washed with diethyl ether (2 x 5 mL). A 'H NMR spectrum of the sample in acetone-& was then obtained and a 'J(H,D) = 25.2 Hz was confirmed by performing an inversion recovery pulse sequence on the sample in order to null out the $-Hz ignal (Figure 3). Preparation of Ru(H)z(dppf)z (4). Under Ar, RuH(cod)(NHz- NMez)3]PF6 (0.294 g, 0.55 "01)was dissolved in ethanol and transferred to an addition funnel. This pale beige solution was added slowly to a solution of bright yellow dppf (0.628 g, 1.14 "01)in ethanol under Ar and refluxed for 1.5 h. The solution immediately tumed orange but with continuous stirring faded to a pale yellow. The solution was cooled and the yellow precipitate was filtered out and 31P NMR RuH2, 'J(H,P) = 7.2 Hz). 31P NMR (THF): 6 53.3 s). I I I Figure 3. HD resonance in the 'H NMR spectrum of trans-[Ru(HD)- Cl(depe)z]BF4 in CDzClz observed by nulling the peak due to [Ru- (Hz)Cl(depe)z]+ by use of an inversion recovery method. -14.2 -14.3 -14.4 ppm washed with ethanol and ether and dried under vacuum to yield 0.45 (60%) of 4. This product is also obtained if the reaction is done under 1 atm of Hz. The complex can be recrystallized by addition of hexanes to a concentrated solution of 4 in CHzC12. FAB MS: calcd for C68Hs8- F~zP~'~Ru, 212; obsd, 1211 (M+ - H), 1210 (Mf - 2H), 655 (M+ - 3H - dppf). Anal. Calcd for C6&l&ezP.&u: C, 67.4; H, 4.8. Found: C, 66.9; H, 4.8. 'H NMR (CDzCl;?, 200 MHz): 6 -10.4 (AA'MM'Xz spin system containing pseudo dt, ZJ(H,P) = 39, 30 Hz, RuH2). 31P NMR (CDzClZ): 6 37.4 (br s), 49.3 (br s). Acidity Measurements. Approximately 6 mg of 1 and an equimolar amount of base were dissolved in either CDZClz or THF-d8 at 20 "C. The 'H NMR and NMR spectra were taken within 30 min and again after 24 h. Resonances were integrated with care as described previously.' When the base was PEtPhz, the equilibrium constant was 0.070 0.005 in CDzClZ. Complex 4 (30 mg) and an excess of acid ([HPPh3]BF4, [HPCyz- PhIBF4, [HPEtPhzIBFh or [HPCy3]BFd) were dissolved in 1.5 mL of CDzClZ. The 'H NMR and 31P NMR spectra were taken within 30 min. The 'H NMR pectra of the reaction of either mCyzPhIBF4 or [HPEtPhz]BF4 with 1 showed separate peaks for hydride-containing reactants and products: -10.4 (m, 4) and -7.9 ppm (q, zJ(H,P) = 10 Hz, [Ru(H)3(dppf)z]+ 4H+)6). These were integrated to determine the equilibrium constants (0.008 0.004 and 0.34 0.10, respectively). The 31P NMR spectrum of the reaction with [HPCyzPh]+ showed peaks at 65.5 (bs, 4Hf), 49.3 (br s, 4), 37.4 (br s, 4) and 27.3 ppm (br s, average of shifts of HPCyZPh+ and PCyzPh) with intensities consistent with the equilibrium constant. There was very little reaction with [HPCy,]BF,; only 4 and a trace of 4H+ were observed. The reaction with [HPPhJBF4 completely converted 4 to 4Hf. X-ray Structure Determinations of [RuCl(dppe)2]PF6 (1) and trans-[Ru(Hz)cl(dppe)~]PF6 2a). Crystals of 1 were prepared by slow diffusion of diethyl ether into a solution of 47 mg of complex in 0.35 mL of CHzClZ. This was done without protection from the ar A red block was mounted on a glass fiber. Crystals of 2a were prepared by slow diffusion of diethyl ether into a saturated solution of the complex in CHzClz under 1 atm of Ar. A pale yellow crystal was mounted on a glass fiber. Intensity data were collected on an Enraf-Nonius CAD-4 diffracto- meter for 1 and on a Siemens P4 diffractometer for 2a, using graphite monochromated Mo Ka radiation A = 0.710 73 A). The 0-28 scan technique was applied with variable scan speeds. In each case the intensities of 3 standard reflections measured at constant intervals showed no decay. Data for the compounds were corrected for Lorentz and polarization effects and for absorption.22 For both structures the Ru atom position was solved by the Patterson method and other non- hydrogen atoms were located by successive difference Fourier synthe- ses. Non-hydrogen atoms were refined anisotropically by full-matrix least-squares to minimize Ew(F, - FJZ where w = l/(uz(Fo) - g(F Hydrogen atoms were positioned on geometric grounds (C-H 0.96 A, Vi,, = 0.065(4) A2 for 1 and 0.089(3) Az for 2a). Crystal data, data collection, and least-squares parameters are listed in Table 1. All calculations were performed and diagrams created using SHELXTL- PCZ3 n a 486-66 personal computer. 22) Sheldrick, G. M. SHJ5LXA-90 absorption correction program. J. Appl. (23) Sheldrick, G. M. SHELXTL-PC; iemens Analytical X-ray Instmments Crystallogr., in press. Inc.: Madison, WI, 1993.  Influence of Chloride versus Hydride on H-H Bonding Table 1. and Least-Squares Refinement Parameters" Summary of Crystal Data, Details of Intensity Collection, Inorganic Chemistry, Vol. 33, No. 26, 1994 6281 Table 2. Displacement Coefficients (A2) for 1 Selected Positional Parameters and Equivalent Isotropic complex 1 complex 2a chem formula CszI-b&lFsPsRU CszHsoCW'sRu a, 8, 12.427(2) 15.315(1) b, A 15.565(3) 17.479( 1) C, A 26.759(5) 18.608( 1) A deg 95.94(4) 101.79(1) v, A3 5148.1(13) 4875.9(7) Z 4 4 fw 1078.3 1080.3 space group P2Jc P2Jn T, "C 21 21 A 0.710 73 8, 0.710 73 ecalc, g ~m-~ .39 1.472 p cm-I 5.7 5.99 transm coeff 0.4843-0.9622 0.4483-0.9556 R(Fo), R(F0>6.0u(F0)) = 5.36 R(F0>4.0u(F0)) = 5.05 Rw(Fo), % 6.72 6.38 l/(uz(Fo) + g Fo)z) where g = 0.0016 for 1 and g = 0.0007 for 2a. "R = CllFol - ~clIEI~ol w = (Cw(lFol - ~c1)2/CI~012)"2~ = Cl181 CIS11 C(121 Figure 4. Structure of the cation of [RuCl(dppe)z]PFs showing thermal displacements at the 25% probability level. Figure 5. Structure of the cation of [Ru(Hz)Cl(dppe)~]PF~ howing thermal displacements at the 25% probability level. The structures of the cations of 1 and 2a, including the crystal- lographic labeling schemes, are shown in Figures 4 and 5. Selected positional parameters and bond distances and angles are listed in Tables 2-5. Results and Discussion Synthesis of [RuCl(dppe)z]PF~, . Attempts to make this useful starting complex by the reaction of truns-RuX2(dppe)2, X = C1 or Br, with NHaF6 in refluxing ethanol were X Y Z Wedb 0.76718(5) 0.71 O(2) 0.8043(2) 0.5 896(2) 0.8017(2) 0.9475(2) 0.7036(7) 0.5990(7) 0.7854(6) 0.9352(7) 0.5171(6) 0.491 (6) 0.9459(6) 1.0204(6) 0.7832(6) 0.7655(8) 0.9654(6) 1.0301 6) 0.79644(4) 0.6761( 1) 0.9353( 1) 0.8541(2) 0.8030( 1) 0.7443 1) 1.0079(6) 0.9621(5) 0.9535(5) 0.9869(5) 0.8680(6) 0.7989(7) 0.8285(6) 0.8053(5) 0.6975(6) 0.9464(6) 0.6306(5) 0.7544(5) 0.83068(2) 0.7786( 1) 0.8180( 1) 0.8237( 1) 0.9143( 1) 0.8409( 1) 0.8420(4) 0.8518(3) 0.7506(3) 0.8348(4) 0.7609(3) 0.8580(3) 0.9336(3) 0.8927(3) 0.9426(3) 0.9755(4) 0.8583(3) 0.7889(3) 0.0326(2) 0.052( 1) 0.040( 1) 0.041 (1) 0.037( 1) 0.037( 1) 0.057(4) 0.049(3) 0.043(3) 0.044(3) 0.046(3) 0.045(3) 0.044(3) 0.040(3) 0.045(3) 0.055(4) 0.038(3) 0.035(3) Only ipso carbons of phenyls. Equivalent isotropic U defined as one-third of the trace of the orthogonalized Uij tensor. Table 3. Selected Bond Lengths (A) and Angles (deg) for 1 Ru-Cl Ru-P(2) Ru-P(4) P(2)-C(2) P(2)-C(21) P(3)-C(29) P(4)-C(28) P(4)-C(47) C(27)-C(28) p(1)-c(3) Cl-Ru-P( 1) P( l)-Ru-P(2) P( l)-Ru-P(3) Cl-Ru-P(4) P(2)-Ru-P(4) Ru-P( 1)-C( 1) C( )-P(l)-C(3) C( l)-P(l)-C(9) Ru-P(2)-C(2) C(2)-P(2)-C(15) C(2)-P(2)-C(21) Ru-P(3)-C(27) C(27)-P(3)-C(29) C(27)-P(3)-C(35) Ru-P(4)-C(28) C(28)-P(4)-C(41) C(28)-P(4)-C(47) P( l)-C(l)-C(2) P(3)-C(27)-C(28) 2.395(2) 2.371(2) 2.372(2) 1.8 15(9) 1.842(9) 1 82 1 9) 1.833(9) 1.837(8) 1.820(9) 1.547(12) 135.8(1) 80.1(1) 95.0( 1) 90.9( 1) 177.0( 1) 112.2(3) 103.1(4) 105.2(4) 107.1(3) 105.7(4) 104.0(4) 11 1.5(3) 103.7(4) 103.8(4) 107.3(3) 105.5(4) 105.1(4) 113.1(6) 112.7(5) Ru-P(l) Ru-P(3) P(l)-C( 1) P(2)-C( 15) P(3)-C(27) P(3)-C(35) P(4)-C(41) C(l)-C(2) ~(1)-c(9) Cl-Ru-P(2) Cl-Ru-P(3) P(2)-Ru-P(3) P( l)-Ru-P(4) P(3)-Ru-P(4) Ru-P( 1)-C(3) Ru-P( 1)-C(9) C(3)-P( 1)-c(9) Ru-P(2)-C( 15) Ru-P(2)-C(21) C(15)-P(2)-C(21) Ru-P(3)-C(29) Ru-P(3)-C(35) C(29)-P(3)-C(35) Ru-P(4)-C(41) Ru-P(4)-C(47) C(41)-P(4)-C(47) P(2)-C(2)-C( 1) P(4)-C(28)-C(27) 2.243 2) 2.238(2) 1.85 1( 10) 1.828(9) 1.835(9) 1.856(8) 1.826(9) 1.841( 8) 1.528( 12) 92.1( 1) 129.2(1) 98.2(1) 98.0(1) 79.6(1) 107.1(3) 125.3(3) 101.4(4) 118.8(3) 116.8(3) 103.1(4) 110.6(3) 126.1(3) 98.5(4) 116.5(3) 118.9(3) 102.3(4) 112.0(6) 11 1.7(5) Only ipso carbons of phenyls. unsuc~essful.~~ runs-RuClz(dppe)2 does not react with reagents such as NaPF6 or NaBF4, or NaBPb that precipitate NaCl; there does appear to be a slow reaction under an H2 atmosphere. However reaction of cis-RuC12(dppe)2 with NaPF6 in THF/ ethanol at 20 "C (eq 1) rapidly produces a yellow precipitate, THF CHzC1z cis-RuC12(dppe)2 I NaPF, 1 [RuCl(dppe),]PF, + NaCl (1) thought to be [Ru(THF)Cl(dppe)z]PF,, which upon recrystal- lization from CH2Clfit20 yields the red, five-coordinate complex [Rucl(dppe)z]PF6, 1. The exclusive presence of the 24) Bressan, M.; Rigo, P. norg. Chem. 1975 14 2286.  6282 Inorganic Chemistry, Vol. 33 No. 26, 1994 Table 4. Displacement Coefficients (A2) for 2a5 Selected Positional Parameters and Equivalent Isotropic X Y Z Chin et al. Ru 0.26489(2) 0.18502(2) 0.02495(1) 0.03251(8) C1 0.3846(1) 0.1283(1) -0.0227(1) 0.0488(3) P(1) 0.1812(1) 0.0683(1) 0.0135(1) 0.0395(3) P(2) 0.3583(1) 0.1617(1) 0.1417(1) 0.0360(3) P(3) 0.3496(1) 0.3005(1) 0.0339(1) 0.0449(3) P(4) 0.1694(1) 0.2047(1) -0.0914(1) 0.0360(3) C( 1) 0.0699(3) 0.0879(3) -0.0453(3) 0.060(2) C(2) 0.4593(3) 0.2204(3) 0.1459(2) 0.053(1) C(3) 0.4307(3) 0.2988(3) 0.1222(3) 0.062(2) C(4) 0.0623(2) 0.1678(2) -0.0781(2) 0.045(1) C(11) 0.2247(3) -0.0150(2) -0.0269(2) 0.045(1) C(21) 0.1489(2) 0.0300(2) 0.0963(2) 0.042(1) C(31) 0.4022(3) 0.0661(2) 0.1650(2) 0.041(1) C(41) 0.3243(3) 0.1919(2) 0.2261(2) 0.039(1) C(51) 0.4139(3) 0.3151(3) -0.0367(3) 0.064(2) C(61) 0.2998(4) 0.3939(3) 0.0436(3) 0.063(2) C(71) 0.1903(3) 0.1556(2) -0.1723(2) 0.047(1) C(81) 0.1408(2) 0.3013(2) -0.1252(2) 0.041(1) Only ipso carbons of phenyls. Equivalent isotropic U defined as one-third of the trace of the orthogonalized Uv tensor. Table 5. Bond Lengths (A) and Angles (deg) for 2an Ru-C1 2.407( 1) Ru-P( 1) Ru-P(2) 2.379( 1) Ru-P(3) Ru-P(4) 2.377( 1) P(l)-C( 1) P(l)-C(ll) 1.825(4) P(l)-C(21) P(2)-C(2) 1.845(4) P(2)-C(31) P(2)-C(41) 1.832(4) P(3)-C(3) P(3)-C(51) 1.814(6) P(3)-C(61) P(4)-C(4) 1.825(4) P(4)-C(71) c(2)-c(3) 1.478(6) P(4)-C(81) 1.825(4) c(1)-c(4) Cl-Ru-P( 1) 92.9(1) P(l)-Ru-P(2) 98.4(1) P( l)-Ru-P(3) 178.7( 1) Cl-Ru-P(4) 95.6(1) P(2)-Ru-P(4) 178.2(1) Ru-P(l)-C( 1) 107.7( 1) C(1)-P(1)-C(l1) 105.8(2) C(l)-P(l)-C(21) 100.9(2) Ru-P(2)-C(2) 106.6(1) C(2)-P(2)-C(31) 103.6(2) C(2)-P(2)-C(41) 100.7(2) RU P(3) - C(3) 107.7(2) C(3)-P(3)-C(51) 106.3(2) C(3)-P(3)-C(61) 98.3(2) Ru-P(4)-C(4) 103.2(1) C(4)-P(4)-C(71) 105.1(2) C(4)-P(4)-C(81) 102.4(2) P(1)-C(1)-C(4) 113.1(3) P(3)-C(3)-C(2) 112.6(3) Only ipso carbons of phenyls. Cl-Ru-P(2) Cl-Ru-P(3) P( 2) -Ru-P( 3) P(l)-Ru-P(4) P(3)-Ru-P(4) Ru-P( 1)-C(11) Ru-P( 1)-C(21) C(ll)-P(l)-C(21) Ru-P(2)-C(31) Ru-P(2)-C(41) C(31)-P(2)-C(41) Ru-P(3)-C(51) Ru-P(3)-C(61) C(5 )-P(3)-C(61) Ru-P(4)-C(71) Ru-P(4)-C(81) C(71)-P(4)-C(81) P(2)-C(2)-C(3) P(4)-C(4)-C( 1) 2.396( 1) 2.387( 1) 1.859(4) 1.838(4) 1.819(4) 1.847(4) 1.826(5) 1.818(4) 1.520(6) 84.5(1) 86.0(1) 82.2(1) 79.9(1) 99.5(1) 118.8( 1) 117.8(1) 103.8(2) 120.7(1) 102.5(2) 115.8(2) 122.1 2) 104.3(2) 120.5( 1) 120.5( 1) 102.7(2) 107.9(3) 112.4(3) 120.0( 1) two triplet resonances for 1 in the 31P NMR spectrum of the reaction mixture in CHzClz suggests that the yield of eq 1 is quantitative. We have preliminary evidence that the complex can also be prepared by the reaction of AgBF4 with trans- RuCl~(dppe)z n CH& at room temperature. The parent ion for 1 in an NPOE matrix was detected by FAB MS. In an NBA matrix, the ion [RuCl(PF6)(dppe)2]+ was the most intense peak in the FAB MS. This unusual observation of a cationic complex associating with the anion suggests that the PF6- anion is coordinated in the gas phase. 1 was also characterized by a single crystal X-ray diffraction study and by solid-state and solution NMR studies (see below). Structure of [RuCl(dppe)2]PF6 in the Solid State. The crystal structure of 1 consists of distorted trigonal bipyramidal (tbp) cations [RuCl(dppe)z]+ (Figure 4) and discrete octahedral PF6- anions. The bidentate dppe ligands span axial and equa- torial positions and the chloride ligand is equatorial. The axial phosphorus atoms P(2) and P(4) (Pm) are each 2.372(2) A away from the ruthenium, with the P(2)-Ru-P(4) angle being 177.0- (1)". The bite angles of the dppe ligands are 80.1(1) and 79.7- (1)" for P(l)-Ru-P(2) and P(3)-Ru-P(4), respectively. The major distortion from tbp geometry is a change from a trigonal to a Y-shape in the equatorial plane. The two equatorial phosphorus-ruthenium bonds form the top of the "Y" with a P(l)-Ru-P(3) angle of only 95.0(1)". There is definitely a strong electronic preference for such a distortion because the close approach of such large groups seems very unfavorable on the basis of steric repulsion considerations. The srcin of this Y type of distortion has been explained by Rachidi et aLZ5 nd Thom and Hoffmann.26 For a d6 metal, the tbp geometry would give a triplet state since the highest occupied molecular orbitals would be degenerate E type orbitals lying in the equatorial plane. This degeneracy can be lifted if the molecule distorts from a trigonal geometry in the equatorial plane. It has been predicted that strong o-donors such as tertiary phosphines prefer to distort to the two top arms of the Y . Weak ndonors such as chloride prefer the lower leg. This is why the two bulky PPhz groups of P( 1) and P(3) in 1 adopt the unusually small angle of 95.0(1)". The Y is distorted because the chloride in 1 is closer to P(3); P(l)-Ru-Cl= 135.8(1)" and P(3)-Ru-C1= 129.2(1)". This distortion is so great in the complex [Rucl(d~ype)2]PF6'~ that the complex becomes almost square pyramidal with the equatorial planar arrangement of atoms described by a T-shape. The chloride in that complex is moved much more toward (1)". Despite the larger bulk of the cyclohexyl groups relative to the phenyl groups, the two equatorial P atoms in [RuCl- (dcype)z]+ are actually closer together than in the dppe com- plex: P(l)-Ru-P(3) = 93.1(1)". The complex Ir(H)zCl(P'- BuzPh)z has a distorted Y in the equatorial plane with an HIrH angle of 72.7" and unequal ClIrH angles of 131.1 and 156.2".12 HF ab initio calculations suggest that the Y can distort toward the T in this way as long as the two pure a-bonding ligands (H in the iridium case and therefore P in the case of 1) maintain a constant, small angle with the metal. The complexes MCl- (dppe)2, M = Tc,15 Re,27 have equatorial angles and distortions that are comparable to those of 1 while the symmetrical complex Re(HzBEt2)(ra~-tetraphos- ) is undistorted with equal Peq- Re-B angles.28 The Ru-Cl distance of 2.394(3) A in 1 is marginally shorter than that observed in [Ru(Hz)Cl(dppe)z]+ (see below). This distance is within one standard deviation of the Ru-Cl distance (2.41(4) A obtained by averaging over 102 Ru-C1 distances in six-coordinate complexes, where Cl is not trans to hydride.29 It is near the lower quartile of Ru-C1 distances for 7 five-coordinate complexes.29 Therefore if there is Ru-Cl bonding in 1, it is similar to that observed in other complexes. The Ru-Cl bond in 1 is shorter than the Tc-C1 bond in TcC1- (dppe)z (2.432(2) presumably because of the positive charge on Ru(I1) vs Tc(1). P(1): P(l)-Ru-Cl = 119.1(1)" and P(3)bRu-Cl 147.4- (25) Rachidi, I. E.; Eisenstein, 0.; ean, Y. New J. Chem. 1990 14 671- 617. (26) Thorn, D. L.; Hoffmann, R. New J. Chem. 1979 3 39. (27) Hughes, D. L.; Pombeiro, A. J. L.; Pickett, C. J.; Richards, R. L. J. Organomet. Chem. 1983 248, C26-C28. (28) Jia, G.; Lough, A. J.; Morris, R. H. J. Organomer. Chem. 1993 461 147-156. Only the equatorial P and B atoms in the complex Re(H2- BEt2)(rac-ktraphos-l) are used to defme the Y ; the bridging hydrides are ignored. (29) Orpen, A. G.; Brammer, L.; Allen, F. H.; Kennard, 0.; Watson, D. G.; Taylor, R. J. Chem. SOC., alton Trans. 1989 S1.
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