Organometallics 1989,8,2866-2871
2866
Binuclear Ruthenium Complexes Employing Bis(dimethy1phosphino)methane (dmpm). Crystal and Molecular Structures of Ru,( dmpm), (CO) 5CsH5CH3and Ru, (dmpm) (CO) 4( PhCCPh)
,
Kimberly A. Johnson and Wayne L. Gladfelter' Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455 Received April 10, 1989
T h e reaction of bis(dimethy1phosphino)methane with R u ~ ( C O under ) ~ ~ CO pressure at 120 "C leads to this complex the quantitative formation of the binuclear ruthenium complex R ~ , ( d m p m ) ~ ( C OAlthough )~ was previously unreported, the s ectroscopic data and X-ray crystallographic analysis [ P l space group, a = 10.569 (2) A, b = 11.964 (2) c = 12.232 (4) A, LY = 77.22 (2)O, = 77.53 (3)O, y = 75.14 (3)O, V = 1437 (1) A3, 2 = 21 show that it has a structure analogous to that found for related bmucleatmg diphosphines. T h e reaction of R ~ ~ ( d m p m ) , ( C Owith ) ~ acids such as HBF4 occurs rapidly and leads t o quantitative protonation of the metal-metal bond forming [HRuz(dmpm),(CO),]BF4. The reaction with diphenylacetylene ~ H & Cwas C ~shown H ~ ) to , contain a occurs at 90 "C in toluene leading t o R U ~ ( ~ ~ ~ ~ ) ~ ( C O ) ~ ( C which az-bridging acetylene ligand by X-ray crystallograph [m1/aspace group, a = 13.140 (3) A, b = 15.157 2 = 41. Although the analogous product can be (4) A,c = 16.280 (3) A,p = 92.56 (2)O, V = 3239 (2) isolated by treating R ~ ~ ( d m p m ) ~ ( w Cit Oh)MeOzCCCCOzMe ~ a t 70 "C, several intermediates can be observed by conducting the reaction at lower temperatures.
i,
i3,
Introduction
As p a r t of our interest in studying t h e homogeneous catalytic carbonylation of nitro aromatic^,'-^ we have been a t t e m p t i n g t o prepare mono- and polynuclear complexes that m a y be similar to some of the proposed catalytic intermediates. Because several diphosphine r u t h e n i u m complexes have been shown to be effective for this catalytic process," we have recently focused our attention o n this class of compounds. One of the preparations of these complexes involves heating R u ~ ( C O and ) ~ ~t h e diphosphine ligand under elevated pressures of carbon m ~ n o x i d e . ~ During t h e course of studying different phosphines, we discovered a remarkably clean conversion of R U ~ ( C Oand )~~ bis(dimethy1phosphino)methane ( d m p m ) i n t o Ruz(dmpm)z(CO),. Details of t h e synthesis, structure, a n d some reactivity studies of this very reactive dimer are described in this paper. Experimental Section General Data. Ru3(C0)', and bis(dimethy1phcephino)methane (dmpm) were purchased from Strem and used without further purification. Fluoroboric acid (HBF,) and dimethyl acetylenedicarboxylate were purchased from Aldrich and used without further purification. Diphenylacetylene was used as purchased from Alfa. The carbon monoxide was used as received from Matheson. Toluene and diethyl ether (Et20) were dried by distillation from sodium benzophenone ketyl under nitrogen. Hexane was dried over sodium, and methylene chloride (CH2Clz) was dried over calcium hydride. Both were distilled under Nz prior to use. All reactions were conducted under a nitrogen atmosphere by using standard Schlenk techniques. Infrared spectra were obtained on a Mattson Cygnus 25 FTIR spectrom(1) Kunin, A. J.; Noirot, M. D.; Gladfelter, W. L. J. Am. Chem. SOC.
1989, I l l , 2739.
(2)Smieja, J. A.;Gladfelter, W. L. Inorg. Chem. 1986, 25, 2667. (3) Smieja, J. A.; Gozum, J. E.; Gladfelter, W. L. Organometallics 1987, 6, 1311. (4)Grate, J. H.;H a " , D. R.; Valentine, D. H. (a) U.S. Patent 4,600,793,1986. (b) U.S. Patent 4,603,216,1986. (c) U S . Patent 4,629,804,1986. (d) U.S.Patent 4,705,883,1987. (5)Sanchez-Delgado, R. A.; Bradley, J. S.; Wilkinson, G. J. Chem. SOC.,Dalton Trans. 1976, 399.
eter. 'H NMR were collected on an IBM AC-200 spectrometer, and 13C NMR spectra were collected on an IBM AC-300 spectrometer. 31PNMR spectra were recorded on a Nicolet NFT 300-MHz spectrometer. Elemental analyses were performed by M-H-W Laboratories. Table I contains a summary of the spectroscopic data. Preparation of R ~ ~ ( d m p m ) , ( C O )RU~(CO)~, ~. (470 mg, 2.20 mmol of Ru) and dmpm (300 mg, 2.20 "01) in 45 mL of toluene were placed in a 75-mL high-pressure Parr reactor equipped with a magnetic stirbar. The reactor was loaded and sealed in the drybox. The sealed reactor was placed in an aluminum thermal well set a t 120 "C and pressurized to 1200 psig with CO. The reaction was stirred under these conditions for 12-16 h, then allowed to cool to room temperature, and vented. The contents were removed from the reactor in the drybox via syringe and transferred to a 100-mL round-bottom flask equipped with a stopcock. The orange-yellow solution was condensed under vacuum and crystaked by cooling the saturated solution. Large, transparent, air-sensitive, orange crystals were collected by removing the solution via cannula and then washing with hexane. Opaque yellow crystals resulted from drying under vacuum. Yield 645 mg, 95%. 13C NMR (CD2C12): 6 21.13 (quint, Jcp = 9 Hz, Me), 39.44 (quint, Jcp= 12 Hz, CH,), 227.17 (quint, JcP = 8 Hz, C, 29.3; H, 4.5;P, 20.2. CO). Anal. Calcd for R~,(dmpm)~(CO)~: Found: C, 29.14; H, 4.66; P, 19.98. Mass spectrum ("Ru): 615 (5% re1 int, [PI+);fragments observed [P - nCO]+, where n = 1-5. Preparation of [ H R ~ ~ ( d m p m ) ~ ( C 0 ) ~Ruz(dmpm)zlBF~ was charged to a 100-mL 3-neck flask (CO), (100 mg, 0.163 "01) equipped with a stirbar, gas adapter, and pressure-equalizing addition funnel and then dissolved in CH2C12. HBF4.Eh0 (31 wL, 0.163 mmol) was diluted in CHzClz (10 mL) and then added dropwise over 30 min. The yellow solution was stirred at room temperature for 2 h. The solution was condensed to half the original volume under vacuum, and then EGO waa added via syringe until the solution became cloudy. Yellow, slightly airsensitive crystals were obtained from an approximately 1:l mixture of CH,Cl,/EhO by slow cooling. Yield 97 mg,85%. Anal. Calcd for [HR~,(dmpm)~(C0)~1BF,: C, 25.65; H, 4.13; P, 17.25. Found C, 25.27; H, 4.09; P, 17.25. P r e p a r a t i o n of Ru,(dmpm),(CO),(PhCCPh). Ru2(dm~m),(CO)~ (50mg,0.08"01) was charged to a 1 " L %neck flask equipped with a stirbar, gas adapter, and pressureequalizing addition funnel and then dissolved in toluene (10 mL). Diphenylacetylene (14.5 mg, 0.08 mmol) was dissolved in toluene (10 mL) and then added dropwise over 15 min. The solution was
0276-7333/89/2308-2866$01.50/00 1989 American Chemical Society
Organometallics, Vol. 8, No. 12, 1989 2867
Binuclear Ruthenium Complexes Table 1. SDectroscoDic Data compd
vco, cm-' 1954 m, 1916 s, 1892 s, 1874 m, 1694 m (CH2C1,) 2020 s, 1980 s, 1705 m (CH2C12)
1973 s, 1939 s, 1909 m, 1888 m
(toluene)
(R = C0,Me)
1982 m, 1952 s, 1923 m, 1900 w
(toluene)
'H NMR, ppm 1.55 (t, J I I = ~ 1.42 Hz, 24 H), 1.96 (quint, JHp= 4.63 Hz, 4 H). (CDX1,) . _ - . -10.2 (quint, J H =~ 10.8 Hz, 1 H), 1.69 (s, 24 H), 2.15 (quint, JIIp= 5.0 Hz, 4 H), (CD2C12) 1.10 (s, 12 H), 1.14 (s, 12 H), 1.23 (mult, 2 H), 2.40 (quint, J&. = 6'Hz, 2 H), 6.90 (mult, 2 H), 7.25 (mult, 8 H) (c&) 1.09 (s,12 H), 1.17 (mult, 2 H), 1.45 (s, 12 H), 2.77 (mult, 2 H), 3.65 ( 8 , 6 H) (C&)
31PNMR, ppm (re1 to H3PO4) 9.1 (s) (CD2ClZ) 4.1
(9)
-3.16
-4.0
(CDZC12)
(5)
(8)
(C&)
(CsDA . _
heated to 95 "C for -25 h. IR spectroscopy indicated complete Table 11. Summary of CrsstallortraDhic Data reaction with prominent new YCO bands at 1973 (s), 1939 (s), 1909 RuAdm~m)~(C0),- R~~(dmpm)~(CO),(m), and 1888 (m) cm-l. The solution was condensed to apC,Hn (PhCCPh) proximately half the original volume. Hexane (2 mL) was added Crystal Parameters and the solution condensed further until the air-stable solid began triclinic monoclinic cryst system to form. X-ray quality crystals were obtained by cooling this space group pi Ella saturated solution. Yield: 51 mg, 83%. 13C NMR (CD2C12): 6 formula Ru2C22H3605P4 RUZC28H3804P4 20.2 (quint, JcP = 10 Hz, Me), 22.4 (quint, Jcp = 7 Hz, Me), 40.1 fw 706.56 164.64 (quint, Jcp = 12 Hz, CH2),122.0 (s, para Ph), 127.3 (8, meta Ph), 10.569 (2) 13.140 (3) a, A 129.4 (s, ortho Ph), 149.6 (quint, J c P = 3.7 Hz, CPh), 154.9 (s, 11.964 (2) 15.157 (4) b, A ipso C on Ph), 200.3 (m, CO), 211.4 (m, CO). Mass spectrum 12.232 (4) 16.280 (3) c, A (lo2Ru): 738 (55% re1 int, [ P - CO]+ fragments observed [ P 77.22 (2) 90 n, deg nCO]+, where n = 2-4. Anal. Calcd for R ~ ~ ( d m p m ) ~ ( C O ) ~ -P, deg 77.53 (3) 92.56 (2) (PhCCPh): C, 43.97; H, 4.97; P, 16.21. Found: C, 43.76; H, 5.05; 75.14 (3) 90 P , 16.33. 1437 (1) 3239 (2) . . . . 2 4 P r e p a r a t i o n of R U ~ ( ~ ~ ~ ~ ) ~ ( C O ) ~ [ C ~ Ru2(CO~CH~)~]. p(calcd), g cm-3 1.633 1.568 ( d m ~ m ) ~ ( C(50 O ) mg, ~ 0.08 "01) was charged to a 100-mL 3-neck temp, "C -85 (2) 24 (1) flask equipped with a stirbar, gas adapter, and pressureequalizing abs coeff, cm-' 12.79 11.39 addition funnel and then dissolved in toluene (10 mL). Dimethyl cryst dimens, mm 0.400 X 0.500 X 0.600 0.350 X 0.250 X 0.150 was dissolved in toluene acetylenedicarboxylate (10 pL, 0.08 "01) 110-84 trans factors, max 115-92 (10 mL) and then added dropwise over 10 min. The color changed to min, % from yellow to bright red immediately following the addition. An abs correct applied empirical (DIFABS) empirical (DIFABS) IR spectrum of the solution after 2 h at room temperature showed a mixture of products with bands at 2033,1980,1964,1952,1934, Measurement of Intensity Data 1917,1892,1872,and 1693 cm", where the final four bands were diffractometer Enraf-Nonius CAD-4 assigned to unreacted starting material. The reaction was warmed radiation Mo K a (A = 0.71073 A) to 70 "C and allowed to stir, with heating, overnight. After 16 monochromometer graphite crystal programs used h a t 70 "C, the orange color had disappeared leaving a bright TEXSAN method of struct Patterson method Patterson method yellow solution. The solution was condensed to -112 the original soln volume, then hexane (10 mL) was added, and the solution was scan type w-2e w-2e condensed further until solid began to form. Air-stable, crystalline scan range, deg 0-50 0-55.9 solid was obtained by slowly cooling this saturated solution. Yield reflctions measd h,*k,+l h,k,il 51 mg, 86%. Mass spectrum ('"Ru): 730 (60% re1 int, [PI+; no. of unique 5633 8109 fragments observed [ P - nCO]+ where n = 1-4. Anal. Calcd for reflctns R u ~ ( ~ ~ ~ ~ ) ~ ( C O ) ~ [ C ~C,( C32.88; O ~ CH,H ~4.66; ) ~P, ] :16.97. 6273 no. of reflctns used 4674 Found: C, 33.09; H, 4.74; P, 16.81. la cutoff 30 X-ray Crystallographic Studies. A. R ~ , ( d m p m ) ~ 0.05 0.05 P (CO)&,H,CH,. Orange crystals were grown as described above. 1.4845 X lo-' extinctn coeff 1.1814 X lo4 A suitable crystal was removed directly from the supernatant and R 0.033 0.051 coated with a high viscosity hydrocarbon, STP (motor oil 0.050 Rw 0.056 treatment), mounted on a fiber, and cooled to -85 "C. Table I1 1.10 error in observn of 1.93 includes the details of the structural analysis. A preliminary peak unit wt search of 25 centered reflections (30" < 28 < 60") indicated that the crystal was triclinic, and the Pi space group was chosen. scattering factors used in the calculations were taken from the Successful refinement of the structure verified the choice of this usual tabulations,6 and the effects for anomalous dispersion were space group. During data collection no decay of intensity was included for the non-hydrogen atoms. The positional parameters, observed in three check reflections. All non-hydrogen atoms of bond distances, and bond angles are listed in Tables 111-V. B. R~~(dmpm)~(C0),(PhCCPh). Yellow crystals were grown the dimer were refined anisotropically. Hydrogen atoms were included in the structure factor calculation in idealized positions as described above. A suitable crystal was mounted on a fiber, and a preliminary peak search of 24 centered reflections (25" < using dc-H = 0.95 8, and an isotropic temperature factor 20% greater than the B, value of the carbon to which they were bonded. The toluene molecule was refined as a rigid group having (6) (a) Cromer, D. T.; Waber, J. T. International Tables for X-ray idealized bond lengths and angles. The hydrogen atoms of the Crystallography; Kynoch Press: Birmingham, England, 1974; Vol, IV, toluene methyl group were not included. The maximum and Table 2.2A. Cromer, D. T. Ibid. Table 2.3.1. (b) Cromer, D. T.; Ibers, minimum peaks on the f i a l difference Fourier map corresponded J.A. International Tables for X-ray Crystallography; Kynoch Press: to 1.20 and -0.94 e/A3, respectively. The values of the atomic Birmingham, England, 1974; Vol. IV, Table 2.2C.
2868 Organometallics, Vol. 8, No. 12, 1989
Johnson and Gladfelter
Table 111. Positional Parameters for RuddmDm),(COh atom X Y 2 -0.03520 (2) 0.13864 (2) 0.19977 (2) 0.12195 (2) 0.25362 (2) 0.28681 (2) -0.0210 (3) 0.1520 (3) 0.3641 (3) -0.0781 (2) 0.1261 (2) 0.4578 (2) -0.1637 (4) 0.0506 (3) 0.2252 (3) -0.2462 (3) -0.0017 (2) 0.2387 (3) 0.0372 (3) 0.1938 (3) 0.0431 (3) 0.0784 (3) 0.2263 (3) -0.0501 (2) 0.1992 (4) 0.3335 (3) 0.1419 (3) 0.2428 (3) 0.3862 (3) 0.0586 (2) 0.1704 (4) 0.2820 (3) 0.4143 (3) 0.2026 (3) 0.3035 (3) 0.4901 (3) -0.21184 (9) 0.30039 (8) 0.20341 (8) 0.1243 (1) -0.03712 (8) 0.20947 (8) -0.05122 (9) 0.41680 (8) 0.30217 (8) 0.29708 (9) 0.08862 (8) 0.28485 (8) -0.1715 (4) 0.4385 (3) 0.2083 (3) 0.2486 (3) -0.0491 (3) 0.2962 (3) -0.3484 (4) 0.2854 (3) 0.3223 (4) -0.2986 (4) 0.3410 (3) 0.0827 (3) -0.0073 (4) 0.5600 (3) 0.2692 (3) -0.1504 (4) 0.4212 (3) 0.4426 (3) 0.2223 (4) -0.0739 (3) 0.0750 (3) 0.0642 (4) -0.1704 (3) 0.2729 (4) 0.4291 (4) 0.0907 (3) 0.1605 (4) 0.3921 (4) 0.0511 (4) 0.4005 (4) Table IV. Bond Distances (A) in Ru2(dm~m)dCO), A. Metal-Metal and Metal-Ligand Ru(l)-Ru(2) 2.8928 (8) Ru(2)-P(21) 2.319 (1) Ru(l)-P(ll) 2.320 (1) Ru(2)-P(22) 2.335 (1) R~(l)-P(12) 2.331 (1) Ru(2)-C(21) 1.936 (3) Ru(l)-C(ll) 1.859 (4) Ru(2)-C(22) 1.865 (5) Ru(l)-C(12) 1.939 (3) Ru(2)-C(O) 2.114 (3) Ru(l)-C(O) 2.091 (4) B. Intraligand Distances 1.825 (4) P(21)-C(1) 1.820 (4) P(22)-C(2) 1.163 (5) C(21)-0(21) c(12)-0(12) 1.148 (4) C(22)-0(22) C(O)-O(O) 1.190 (4)
P(ll)-C(l) P(12)-C(2) C(ll)-O(ll)
1.825 (4) 1.816 (4) 1.145 (4) 1.153 (6)
Table V. Bond Angles (deg) for R ~ ~ ( d m ~ m ) ~ ( C 0 ) , A. Ligand-Metal-Ligand C(ll)-R~(l)-C(12) 117.4 (2) C(22)-R~(2)-C(21) 115.4 (2) C(ll)-Ru(l)-C(O) 103.1 (2) C(22)-Ru(2)-C(O) 101.0 (2) Cfll)-Ru(l)-P(12) 88.1 (1) C(22)-R~(2)-P(22) 89.0 (1) C(ll)-RU(l)-P(ll) 85.7 (1) C(22)-Ru(2)-P(21) 87.2 (1) C(ll)-Ru(l)-Ru(2) 149.9 (1) C(22)-Ru(2)-Ru(l) 147.2 (1) C(l2)-Ru(l)-C(O) 139.4 (2) C(2l)-Ru(2)-C(O) 143.1 (2) C(12)-Ru(l)-P(12) 92.8 (1) C(21)-Ru(2)-P(22) 93.0 (1) C(12)-R~(l)-P(ll) 92.6 (1) C(21)-R~(2)-P(21) 89.9 (1) C(12)-Ru(l)-Ru(2) 92.6 (1) C(21)-Ru(2)-Ru(l) 97.4 (1) C(O)-Ru( 1 )-P( 12) 90.61 (9) C(O)-Ru( 2)-P( 22) 92.93 (8) C(O)-Ru( 1)-P( 11) 87.99 (9) C(O)-Ru( 2)-P( 21) 86.42 (8) C(O)-Ru(l)-Ru(Z) 46.9 (1) C(O)-Ru(Z)-Ru(l) 46.2 (1) P(12)-R~(l)-P(ll) 173.10 (4) P(22)-Ru(2)-P(21) 175.94 (5) P(12)-Ru(l)-Ru(2) 92.53 (3) P(22)-Ru(2)-Ru(l) 90.76 (3) P(ll)-Ru(l)-Ru(B) 91.67 (3) 91.45 (3) P(21)-Ru(2)-Ru(l) B. Metal Carbonyls and Phosphines Ru(l)-P(ll)-C(l) 115.8 (1) Ru(2)-P(21)-C(l) 114.8 (1) Ru(l)-P(12)-C(2) 115.0 (1) R~(2)-P(22)-C(2) 114.9 (1) Ru(l)-C(ll)-O(ll) 177.8 (3) R~(2)-C(22)-0(22) 177.0 (3) Ru(l)-C(12)-0(12) 179.0 (5) Ru(2)-C(21)-0(21) 176.4 (3) Ru(1)-C(0)-O(0) 136.5 (3) Ru(2)-C(O)-O(O) 136.1 (3) 113.1 (2) P(ll)-C(l)-P(21) 111.7 (2) P(12)-C(2)-P(22) Ru(l)-C(O)-Ru(B) 86.9 (1) 28 < 36.2O) indicated that the crystal WEIB monoclinic. The space group was found to be P2Ja based on the systematic absences (h01,h = 2n + 1; OkO,k = 2n + 1). During data collection no decay of intensity was observed in three check reflections. Table I1 included the details of the structural analysis. All non-hydrogen atoms of the dimer were refined anisotropically, and the hydrogen
Table VI. Positional Parameters for Ruz(dmpm)z(CO),(PhCCPh) atom
X
Y
2
0.34124 (3) 0.19550 (3) 0.4452 (4) 0.5079 (3) 0.3013 (4) 0.2760 (3) 0.1668 (4) 0.1505 (3) 0.1067 (4) 0.0505 (3) 0.4602 (1) 0.2276 (1) 0.3207 (1) 0.07244 (9) 0.4502 (4) 0.1153 (4) 0.5953 (4) 0.4602 (6) 0.3194 (5) 0.3184 (5) 0.1785 (5) 0.2748 (4) 0.0087 (4) -0.0392 (4) 0.3371 (3) 0.2723 (3) 0.3958 (4) 0.3474 (4) 0.4029 (7) 0.5061 (7) 0.5557 (5) 0.5002 (4) 0.2593 (3) 0.3429 (3) 0.3323 (4) 0.2371 (4) 0.1523 (4) 0.1638 (3)
0.03966 (2) -0.07274 (2) 0.1154 (4) 0.1620 (3) -0.0088 (4) -0.0351 (3) -0.1379 (3) -0.1785 (3) -0,1258 (3) -0.1603 (3) -0.0728 (1) 0.15678 (8) -0.17149 (9) 0.03341 (8) -0.1319 (3) 0.1467 (3) -0.0424 (5) -0,1588 (5) -0.2804 (4) -0.2038 (4) 0.1782 (4) 0.2660 (4) 0.0171 (4) 0.0426 (4) 0.0695 (3) 0.0181 (3) 0.1417 (3) 0.2025 (3) 0.2660 (4) 0.2683 (5) 0.2098 (5) 0.1486 (4) 0.0194 (3) 0.0162 (4) 0.0169 (4) 0.0213 (4) 0.0238 (4) 0.0213 (3)
0.15823 (2) 0.24128 (2) 0.1291 (3) 0.1080 (3) 0.0530 (3) -0.0100 (2) 0.1430 (3) 0.0846 (3) 0.3132 (3) 0.3546 (3) 0.18380 (8) 0.14234 (7) 0.28937 (9) 0.20408 (7) 0.2800 (3) 0.2024 (3) 0.1888 (5) 0.1056 (4) 0.2415 (5) 0.3966 (4) 0.0378 (3) 0.1698 (4) 0.1042 (3) 0.2662 (3) 0.2875 (2) 0.3257 (2) 0.3311 (3) 0.3802 (3) 0.4248 (4) 0.4229 (4) 0.3744 (4) 0.3272 (3) 0.4158 (2) 0.4716 (3) 0.5556 (3) 0.5869 (3) 0.5339 (3) 0.4498 (3)
Table VII. Bond Distances (A) in Ruz(dmpm),(CO),(PhCCPh) A. Metal-Metal and Metal-Ligand Ru(l)-Ru(2) 2.938 (1) Ru(2)-P(21) Ru(l)-P(11) 2.337 ( 2 ) Ru(2)-P(22) R~(l)-P(12) 2.327 (1) Ru(2)-C(21) Ru(l)-C(11) 1.862 (5) Ru(2)-C(22) Ru(l)-C(12) 1.915 (5) Ru(2)-C(OB) Ru(l)-C(OA) 2.156 (4) c(ll)-O(ll) C(12)-0(12) C(21)-0(21) C(22)-0(22) P(ll)-C(l)
B. Intraligand Distances 1.150 (6) P(12)-C(2) 1.137 (6) P(21)-C(1) 1.145 (6) P(22)-C(2) 1.148 (6) C(0A)-C(0B) 1.814 (5) C(0A)-C(1A) C(OB)-C(lB)
2.334 (1) 2.341 (1) 1.905 (5) 1.871 (5) 2.163 (4)
1.813 (5) 1.817 (5) 1.808 (5) 1.329 (6) 1.498 (6) 1.484 (5)
atoms were treated as described above. The phenyl groups were refined as a rigid group having idealized bond lengths and angles. The maximum and minimum peaks on the f i difference Fourier map corresponded to 0.60 and -0.61 e/A3, respectively. The positional parameters, bond distances, and bond angles are listed in Tables VI-VIII.
Results and Discussion Synthesis of Ruz(dmpm)z(CO),. Equation 1 shows the reaction that leads to the preparation of Ru2(dmpm)z(CO)s. Both the high isolated yield and the in-
~ R U ~ ( C+OGdmpm )~~
-
3 R ~ ~ ( d m p m ) ~ ( C+O9CO )~ (1)
frared spectrum of the solution, which shows the presence
Binuclear Ruthenium Complexes
Organometallics, Vol. 8, No. 12, 1989 2869 c2
Table VIII. Bond Angles (deg) for Ru2(dmpm)2(CO),(PhCCPh) A. Ligand-Metal-Ligand C(ll)-R~(l)-C(l2) C(ll)-Ru(l)-C(OA) C(ll)-R~(l)-P(l2) C(ll)-Ru(l)-P(ll) C (1l)-Ru(l)-Ru(2) C(12)-Ru(l)-C(OA) C(12)-Ru(l)-P(12) C(l2)-R~(l)-P(ll) C(12)-Ru(l)-Ru(2) C(OA)-Ru(l)-P(12) C(OA)-Ru(l)-P(ll) C(OA)-Ru(l)-Ru(2) P(l2)-R~(l)-P(ll) P(12)-Ru(l)-Ru(2) P(ll)-Ru(l)-Ru(2)
100.6 (2) 99.8 (2) 88.6 (2) 90.2 (2) 167.3 (1) 159.3 (2) 92.6 (2) 91.9 (2) 91.8 (2) 84.5 (1) 91.4 (1) 68.1 (1) 175.49 (5) 93.75 (4) 86.53 (4)
C(22)-Ru(2)-C(21) C(22)-Ru(2)-C(OB) C(22)-Ru(Z)-P(22) C(22)-Ru(2)-P(21) C (22)-Ru(2)-Ru(1) C(2l)-Ru(2)-C(OB) C(2l)-Ru(Z)-P(22) C(21)-Ru(2)-P(21) C(21)-Ru(Z)-Ru(l) C(OB)-Ru(2)-P(22) C(OB)-Ru(2)-P(21) C(OB)-Ru(2)-Ru(l) P(22)-Ru(2)-P(21) P(22)-Ru(2)-Ru(l) P(21)-Ru(2)-Ru(l)
B. Metal Carbonyls and Other Ligands Ru(l)-P(ll)-C(l) 116.1 (2) Ru(2)-P(21)-C(l) Ru(l)-P(12)-C(2) 114.2 (2) Ru(2)-P(22)-C(2) Ru(l)-C(ll)-O(ll) 177.3 (5) Ru(2)-C(22)-0(22) R~(l)-C(12)-0(12) 177.7 (5) Ru(2)-C(21)-0(21) Ru(l)-C(OA)-C(OB) 112.2 (3) Ru(2)-C(OB)-C(OA) Ru(l)-C(OA)-C(lA) 125.5 (3) Ru(2)-C(OB)-C(lB) C(lA)-C(OA)-C(OB) 122.3 (4) C(1B)-C(0B)-C(0A) P(ll)-C(l)-P(21) 109.9 (2) P(12)-C(2)-P(22)
c10
m
101.4 (2) 99.3 (2) 90.8 (2) 88.0 (2) 167.1 (2) 159.0 (2) 91.8 (2) 93.4 (2) 91.3 (2) 91.4 (1) 83.8 (1) 68.2 (1) 174.84 (5) 86.52 (4) 93.55 (4) 114.1 (2) 116.4 (2) 177.2 (4) 178.7 (5) 111.5 (3) 124.4 (3) 124.0 (4) 110.5 (2)
01
>I c22
9°22
Figure 1. Structure of Ruz(dmpm)z(C0)5showing the atom labels.
are preceded by CO dissociation, are inhibited. The higher CO pressures will also have the effect of shifting the equilibrium shown in eq 2 to the right. To confirm the 2RU3(P-P)3(CO)6+ 3CO ~ R u ~ ( P - P ) ~ ( C O(2) ),
possibility that eq 2 may occur, R ~ & d m p m ) ~ ( Cwas O)~ only of the product, confirm that the reaction is quantiindependently synthesized and treated at 120 'C and 1200 tative. psig of CO for 8 h. Complete conversion to Ru2Several other studies of the reaction of R u ~ ( C Owith )~~ ( d m ~ m ) ~ ( C Owas ) , observed, however, the reverse of eq binucleating phosphines have been reported to lead to the trinuclear clusters Ru3(P-P)(CO)lo,' R U ~ ( P - P ) ~ ( C Oor ) ~ , ~ " ~2 has not been observed. Treatment of R ~ ~ ( d m p m ) ~ ( C O ) , at high temperatures under N2 (refluxing toluene for 12 Ru~(P-P)~(C or ~to) the ~ ~ binuclear ~*~ complexes Ru2(Ph) or under UV irradiation (16 h) failed to cause any P)(CO)710or R U ~ ( P - P ) , ( C O ) ~The . ~ ~compound *~ actually change in the dimer. isolated is a function of the reaction conditions and the Structure of Ru2(dmpm),(CO),. Very large, transstructure of the diphosphine. For instance, excess dppm parent, orange crystals of Ru2(dmpm),(CO), can be grown was found to react with R u ~ ( C Oin ) ~refluxing ~ benzene by slowly cooling a saturated toluene solution. These for 8 h to give Ru3(dppm)&0)&' while photolysis at room crystals begin to degrade as soon as they are removed from temperature of the same solution yields Ru2(dppm),the toluene. Fortunately, solvent loss could be prevented (co)5.7c The photochemical reaction of various diphoswith R U ~ ( C O ) ~ ~by coating the crystals with STP and cooling to -90 'C to phazanes [such as (Me0)2PN(Et)P(OMe)2] collect the data. also leads to binuclear complexes.7d The observation that The structure consists of well-separated solvent and the lower nuclearity products are favored by photolysis dimer units, and, as anticipated, the ruthenium dimer would seem consistent with the known photoinduced (shown in Figure 1) has the same structure as Ru2fragmentation of R u ~ ( C O )In~contrast ~ ~ ~ to this pattern, [ (MeO)2PN(Et)P(OMe)2]2(C0)5.7d With the exception of the photolysis of solutions of dmpm and R u ~ ( C Oleads )~~ the bridging carbonyl, all Ru-L bond distances are longer only to substituted trinuclear clusters.7c in this dmpm-containing dimer. The geometric ligand Thermolysis of the trinuclear clusters containing either arrangement surrounding each metal is best described as dppm or dmpm ligands at temperatures of 80 'C or higher a trigonal bipyramid. The apparent deviations associated leads to products in which the ligand itself has been alwith the bond angles involving the bridging carbonyl (Ctered.I2 For instance, Ru,(dmpm)(CO),, gives HRu3(O)-O(O)) and the adjacent metal disappear by considering (Me2PCHPMe2)(CO), in refluxing toluene.12b Since the that these act as one bonding unit. For example, Rureaction shown in eq 1 is conducted at elevated CO pres(2)-C(O) could be considered as a *-bonding ligand to sure, ligand degradation reactions, which almost certainly Ru(1). The average of C(11)-Ru(1)-C(0) and C(ll)-Ru(1)-Ru(2) is 126.5' and the average of C(12)-Ru(l)-C(O) (7)(a) Cotton, F. A.; Hanson, B. E. Inorg. Chem. 1977,16,3369.(b) and C(12)-Ru(l)-Ru(2) is 116'. The corresponding avBruce, M. I.; Hambley, T. W.; Nicholson, B. K. J. Organomet. Chem. erage angles on Ru(2) are 124.1 and 120.3'. An interesting 1983,247,321.(c) Engel, D. W.; Moodley, K. G.; Subramony, L.; Hainea, R.J. J.Organomet. Chem. 1988,349,393.(d) Leeuw, G.D.; Field, J. S.; systematic difference observed within the structure of Haines, R. J.; McCulloch,B.; Meintjies, E.; Monberg, C.; Olivier, G. M.; Ru,(dmpm),(CO), involves the two Ru-C distances of the Ramdial, P.;Sampson, C. N.;Sigwarth, B.; Steen, N. D.; Moodley, K. G. terminal CO groups. The two carbonyls that are perpenJ. Organomet. Chem. 1984,275,99. (8)(a) Lavigne, G.; Bonnet, J. J. Inorg. Chem. 1981,20, 2713. (b) dicular to the Ru-Ru bond are 0.076 A longer than the Lavigne, G.;Lugan, N.; Bonnet, J. J. Organometallics 1982, 1, 1040. other terminal carbonyls. The small mean deviation of the (9)Smith, A. K.; Cartwright, S.; Clucas, J. A.; Dawson, R. H.; Foster, atoms out of the equatorial plane comprised of the Ru2D. F.; Harding, M. M. J. Organomet. Chem. 1986,302,403. (10)Kiel, G.-Y.; Takata, J. Organometallics 1989,8, 839. (CO), fragment is 0.084 A. A similar deviation of 0.062 (11)(a) Johnson, B. F. G.; Lewis, J.; Twigg, M. V. J. Organomet. A obtains for the Ru2P4fragment, and the dihedral angle Chem. 1974,67,C75. (b) Johnson, B. F. G.; Lewis, J.; Twigg, M. V. J. between these two planes is 91.3'. A calculation of the Chem. SOC.,Dalton Trans. 1975,1876. (c) Desrosiers, M. F.; Wink, D. A.; Trautman, R.; Friedman, A. E.; Ford, P. C. J.Am. Chem. SOC.1986, dihedral angle between the two planes comprised of Ru108,1917. (1)-Ru(2)-P( 11)-P(12) and Ru(l)-Ru(2)-P(21)-P( 22) (12)(a) Lugan, N.; Bonnet, J. J.; Ibers, J. A. J. Am. Chem. SOC.1985, gives a value of 3.75' indicating a small twist exists in the 107,4484.(b) Clucas, J. A.; Foster, D. F.; Harding, M. M.; Smith, A. K. J. Chem. SOC.,Dalton Trans. 1987,277. structure.
2870 Organometallics, Vol. 8, No. 12, 1989 Solution spectroscopic studies were consistent with the solid-state structure. The infrared absorptions were shifted an average of 10 cm-' to lower energy than the analogous compound R ~ ~ ( d p p m ) ~ ( C O The ) ~31P ' ~ NMR exhibited one resonance at 9.09 ppm. The 'H NMR spectrum exhibited one methyl triplet and one methylene quintet, a pattern arising from the virtual coupling of the trans phosphine ligands and indicating that both faces of the Ru2P4arrangement are equivalent on this time scale. The fluxional character of the carbonyls was confirmed by observing the quintet at 227.17 ppm in the 13C NMR spectrum, which is attributed to the five equivalent CO ligands. The dynamic processes for closely related compounds have been studied in detail,13and it is reasonable to suggest that the same fluxional process is operating in Ru~(~PP~)z(CO)~. Reactivity of Ru2(dmpm),(CO),. It was anticipated that the electron-rich phosphines would impart a high degree of reactivity to R~~(dmpm)~(CO),. In addition to this electronic effect the X-ray structural analysis of the dimer indicates that steric congestion is minimal. Consistent with these ideas, protonation of the Ru-Ru bond with HBF4 occurred in high yield upon mixing the reagents. The terminal CO stretching frequencies increased by approximately 70 cm-l, but the bridging CO stretch increased by only 11 cm-'. Although the related dimer [ H R ~ ~ ( d p p m ) ~ ( C 0 )exhibits ~ 1 P F ~four terminal CO abs o r p t i o n ~the , ~ ~energies appear in the same region. The 'H NMR exhibits a quintet in the hydride region at -10.2 ppm. This spectroscopic characterization, and its similarity to structurally characterized compounds, allows the unambiguous assignment of the structure to that shown below.
Johnson and Gladfelter
22
01
6 c4
Figure 2. Structure of R ~ ~ ( d m p m ) ~ ( C 0 ) ~ ( P h C Cshowing P h ) the atom labels.
ilarity in spectroscopic properties confirms the structure of this final product is the same as found for Ru2(dm~m)~(Co),(PhCCPh). Structure of R~~(dmpm),(C0)~(PhCCPh). The structure consists of well-separated units, and, as shown in Figure 2, the connectivity differs from R~~(dmpm)~(CO), by the replacement of the pz-COwith the alkyne. The carbonyls and the alkyne define an equatorial plane surrounding the ruthenium atoms, and the phosphines occupy the axial positions. The angle between the planes comprised of Ru(l)-Ru(2)-C(OA)-C(OB) and Ru(l)-Ru(B)-P(ll)-P(12) is 84.86" and between Ru(l)-Ru(2)-C(OA)-C(OB) and Ru(l)-Ru(2)-P(21)-P(22) is 94.87'. A slight twist of the Ru2P4framework of 10.02" is evaluated by the angle between Ru(l)-Ru(Z)-P(ll)-P(12) and Ru(1)-RuMe, Ye (2)-P(21)-P(22). The alkyne is coordinated to the two Ru ,Me atoms as a u2 ligand with Ru(1)-C(0A) = 2.156 (4) A and Ru(2)-C(OB) = 2.163 (4) A. These values are similar to other Ru-alkyl and Ru-alkenyl Q bonds.15 The C-C linkage of the alkyne has been lengthened to 1.329 (6) A which is in the range of a normal C-C double bond. The maximum deviation from perfect trigonal geometry in the [HRk(dmP)2(Co)slBF4 angles surrounding C(0A) and C(0B) is 8.5". The RuAlkynes were found to react with R ~ ~ ( d m p m ) ~ ( C O ) , (1)-Ru(2) bond distance of 2.9375 (7) A is only slightly under conditions that depended on the substituents bound elongated compared to that found in Ru2(dmpm),(CO),, to the carbons. The reaction of diphenylacetylene with and the remaining distances and angles are similar between R ~ ~ ( d m p m ) ~ ( Crequired O), maintaining a temperature of these two complexes. 95 "C for 1 day. On the basis of mass spectrometry and In binuclear, alkyne complexes that are not constrained elemental analytical data, the yellow product, isolated in by additional binucleating ligands, the more common ar83 % yield, was formulated as Ru,(dmpm),(CO),chitecture involves the p2-s2-alkynebonding mode.16 The (PhCCPh). The singlet observed in the 31PNMR spec0,-bound alkyne ligand has been frequently observed in trum and the differentiation of the phosphine methyl groups in the 'H NMR spectrum indicated that one alkyne (15) See for examples: (a) Lin, Y. C.; Calabrese, J. C.; Wreford, S. S. was bound in some fashion to one face of the complex. The J. Am. Chem. SOC.1983,105,1679. (b) Dyke, A. F.; Knox, S. A. R.; Mead, X-ray structural study described below confirmed the K. A.; Woodward, P. J. Chem. SOC.,Chem. Commun. 1981, 861. (c) formation of the a2-bound alkyne. Cooke, M.; Davies, J. E.; Knox, S. A. R.; Mead, K. A.; Roue, J.; WoodP. Ibid. 1981,862. (d) Holmgren, J. s.;Shapley, J. R.; Wilson, s. ward, The reaction between Ruz(dmpm),(CO), and dimethyl R.; Pennington, W. T. J. Am. Chem. SOC.1986,108,508. acetylenedicarboxylate [C2(C02Me),]occurs under much (16) See for example: (a) Muetterties, E. L.; Pretzer, W. R.; Thomas, milder conditions and is far more complex. Even at room M. G.; Beier, B. F.; Thorn, D. L.; Day, V. W.; Anderson, A. B. J. Am. Chem. SOC.1978, 100, 2090. (b) Day, V. W.; Abdel-Meguid, S. S.; Datemperature a reaction occurs to give a red compound that vestoni, S.; Thomas, M. G.; w. R.; Muetterties, E. L. J. Am. Chem. SOC. proceeds on to several additional compounds, none of 1976,98,8289. (c) Bailey, W. I., Jr.; Cotton, F. A.; Jamerson, J. P.; Kolb, which has been identified. Despite the complexity of this J. R. J. Organomet. Chem. 1976,121, C23. (d) Cotton, F. A.; Jamerson, J. D.; Stults, B. R.J.Am. Chem. SOC.1976, 98, 1774. (e) Sly, W. G. J . stage of the reaction, only one product is isolated (in 83% Am. Chem. SOC. 1959,81,18. (0 Bennett, M. A,; Johnson, R. N.; Robyield) after the solution is heated for 16 h at 70 "C. The ertson, B. B.; Turney, T. W.; Whimp, P. 0. Inorg. Chem. 1976,15,97. (9) mass spectral and elemental analytical data establish the Wang, Y.; Coppens, P. Inorg. Chem. 1976,15,1122. (h) Mills, 0. S.; Shaw, B. W. J. Organomet. Chem. 1968,11,595. (i) Ban, E.; Cheng, P.-T.; Jack, formula as R~~(dmpm)~(CO),[C~(C0~Me),l, and the sim-
l+
(13) (a) Cotton, F. A.; Troup, J. M. J. Am. Chem. SOC.1974,96,4422. (14) Field, J. S.; Haines, R. J.; Sampson, C. N.; Sundermeyer, J.; Moodley, K. G. J . Organomet. Chem. 1987, 322, C7.
T.; Nyburg, S. C.; Powell; J. J. Chem. SOC.,Chem. Commun. 1973, 368. 6 ) Boag, N. M.; Green, M.; Howard, J. A. K.; Spencer, J. L.; Stansfield, R. F. D.; Stone, F. G. A.; Thomas, M. D. 0.;Vicente, J.; Woodward, P. J . Chem. SOC.,Chem. Commun. 1977,930. (k) Dickson, J. L.; Pain, G. N.; Mackay, M. F. Acta Crystallogr., Sect. B 1979, B35, 2321.
Organometallics 1989,8, 2871-2875 binuclear rhodium and iridium complexes containing both dppm and dmpm ligands." Most of the Rh and Ir compounds can only be prepared with the very electron-deficient alkynes such as hexafluoro-2-butyne and dimethyl acetylenedicarboxylate. The anticipated increase in basicity in moving from Rh(1) or Ir(1) to Ru(0) apparently allows the reaction to occur with the less electron-deficient alkyne, diphenylacetylene.
Summary We have described the high yield preparation of a new, (17) (a) Davidson, J. L.; Harrison, W.; Sharp, D. W. A.; Sim, G . A. J. Organomet. Chem. 1972, 46, C47. (b) Dickson, R. S.; Johnson, S. H.; Kirsch, H. F.; Lloyd, D. J. Acta Crystallogr.,Sect. B. 1977, B33,2057. (c) Balch, A. L.; Lee,C.-L.;Lindsay, C. H.; Olmstead, M. M. J. Organomet. Chem. 1979,177, C22. (d) Koie, Y.; Shinoda, S.; Saito, Y.; Fitzgerald, B. J.; Pierpont, C. G. Inorg. Chem. 1980,19,770. (e) Cowie, M.; Southern, T. G. J. Organomet. Chem. 1980,193, C46. (f) Cowie, M.; Dickson, R. S. Znorg. Chem. 1981,20, 2682. (9) Cowie, M.; Southern, T. G. Inorg. Chem. 1982,21, 246.
2871
reactive binuclear ruthenium dimer, R~,(dmpm),(CO)~, in one step from RU~(CO)~, and dmpm. Its structure was determined by X-ray diffraction methods and was found to contain trans phosphines in axial positions and one bridging and four terminal carbonyls in the equatorial plane. Initial reactivity studies found that this highly basic dimer reacts with protons to give [HRu,(dmpm),(CO),]BF,, and with activated or unactivated alkynes. The structure of R~,(dmpm),(C0)~(PhCCPh) was found by X-ray diffraction studies to contain a bridging a,-alkyne. Additional studies of the reactivity of R ~ ~ ( d m p m ) , ( C O ) ~ are in progress.
Acknowledgment. This research was supported by a grant from the National Science Foundation (CHE8714326). Supplementary Material Available: Tables of the H atom ~ i t i o n thermal s~ parameters,and bond angles (20 pages); hth@ of structure factors (75 Pages). Ordering h-h"ation is given On any current masthead page.
Lewis Acid Effects on Selectivity in Nickel-Catalyzed Pentenenitrile Hydrocyanation. Triorganotin Salts as Tunable Lewis Acid Promoters Ronald J. McKinney' and William A. Nugent Central Research and Development Department and Petrochemicals Department, E. I. do Pont de Nemours and Company, Experimental Station, P.0. Box 80328, Wilmington, &la ware 19880-0328 Received May 9, 1989
Anhydrous triorganotin salta, &SnX, have been synthesized and utilized in exploring steric and electronic effects on selectivity in nickel-catalyzedpentenenitrile hydrocyanation. Steric effects are found to dominate the selectivity in the competition both between 3- and 4-pentenenitrile (3PN and 4PN) hydrocyanation and between Markovnikov and anti-Markovnikovaddition of HCN to 4PN. Electronic effects, i.e., Lewis acidity, effect only the activity of the catalyst, but in the complex hydrocyanation system, this can result in yield changes to adiponitrile.
Introduction The Du Pont adiponitrile (ADN) process1 involves nickel-catalyzed hydrocyanation of 3-pentenenitrile (3PN) and produces 2-methylglutaronitrile (MGN), ethylsuccinonitrile (ESN), and 2-pentenenitrile (2PN) as byproducts (eq 1-4). The selectivity to adiponitrile is CHSCH=CHCH,CN e CHXHZCHZCH2CN (1) 3PN 4PN 3PN + CH3CH,CH=CHCN (2) 2PN
ks
4PN + HCN NCCH,CH&H2CHZCN ADN
-
+ NCCHzCHzCH(CH3)CN MGN
(3)
3PN + HCN NCCH2CH,CH(CH,)CN + NCCH2CH(C,H5)CN (4) MGN ESN strongly influenced by the choice of Lewis acid promoter? k4
7 Contribution
No. 4931.
0276-7333/89/2308-2871$01.50/0
For example, Lewis acid promotion of the hydrocyanation catalyst of 3PN at 50 "C with NiL4 [L = P(O-p-t~lyl)~] gives the following selectivities to ADN B(C8H5)3,96%; ZnCl,, 82%; AlC13, 50%.3 In this paper, we have undertaken a systematic study of the role that the Lewis acid plays in controlling the selectivity of addition of HCN to pentenenitrile. In order to accomplish this goal, we have utilized triorganotin salts as tunable Lewis acids and in the process have developed synthetic methods and isolated the first anhydrous triorganotin cations in which the anion is not coordinated to the tin.4 As eq 2-4 indicate, in the hydrocyanation of 3PN, byproducts arise by way of three different reactions, i.e., 2PN from eq 2, MGN from eq 3, and MGN and ESN from eq 4. The isomerization reactions, eq 1-2, have been the (1) Chem. Eng. News 1971,49,30. (2) (a) Tolman, C. A.; McKmey, R. J.; Seidel, W. C.; Druliier, J. D.; Stevens, W. R. Adu. Catal. 1985, 33, 1-46. Recent references on the mechanism of nickel-catalyzed olefin hydrocyanation include: (b) Backvall, J. E.; Andell, 0. S. Organometallics 1986, 5, 2360. (c) McKinney, R. J.; Roe,D. C. J. Am. Chem. SOC.1986,108,5167. (3) Based on eq 3 and 4 only; yield l w from 2PN not included here. (4) Nugent, W. A.; McKinney, R. J.; Harlow, R. L. Organometallics 1984, 3, 1315.
0 1989 American Chemical Society
