365
Organometallics 1995, 14, 365-370
Synthesis and Evaluation of the Bonding Properties toward Rhodium(1)of 2,5-Bis[3-(diphenylphosphino)propyl]thiophene: A New Versatile Ligand with q2, q3, and q7 Modes of Bonding Marie Alvarez, Noel Lugan, Bruno Donnadieu, and R e d Mathieu" Laboratoire de Chimie de Coordination du CNRS, UPR 8241, lit p a r conventions a I'Universitd Paul Sabatier et a Z'htitut National Polytechnique, 205 route de Narbonne, 31077 Toulouse Cedex, France Received June 14, 1994@
The new ligand 2,5-bis[3-(diphenylphosphino)propyllthiophene (2) has been synthesized in four steps from thiophene, and its bonding capabilities with Rh(1) have been evaluated. With (COD)Rh(acac) in the presence of perchloric acid, the complex [(COD)Rh(2)1[C104](3) has been obtained but its low solubility suggests a polymeric structure. The 1,5cyclooctadiene ligand is displaced by CO, leading to complexes that are in equilibrium, depending on the partial pressure of CO. Under a CO atmosphere, only the complex [Rh(C0)3(2)1[C1041(4) is present in solution and its spectroscopic data are consistent with a trigonal-bipyramidal structure in which the two phosphorus atoms are in axial positions. as a mixture of cis Progressive decarbonylation causes the formation of [Rh(CO)~(2)][Cl041 ( 5 ) and trans ( 6 ) isomers (ligand 2 being bidentate through the phosphorus atoms) and of [Rh(C0)(2)1[C1041(71, in which 2 is tridentate binding through the two phosphorus atoms and the sulfur of the thiophene ring. Complete decarbonylation of 7 is achieved through refluxing in acetone solution and leads to [Rh(2)1[C1041(8). The structure of [Rh(2)l+ has been established by an X-ray structure determination of the [Rh(2)1[BPh,J salt (8'). Crystallographic data for 8': monoclinic Czh5-P21/n,a = 11.261(2) 8,b = 15.886(4) 8,c = 29.986(4) 8; B = 96.70(2)"; V = 5149 A3,Z = 4; R = 0.0527, Rw = 0.0586 for 4254 observations and 595 variable parameters. The cation consists of a rhodium atom n bound to the thiophene ring and bound to the two phosphorus atoms of ligand 2.
Introduction In a recent publication we showed that the newly synthesized ligand, 2,5-bis[2-(diphenylphosphino)ethyl]thiophene (1) was a tridentate ligand binding through phosphorus and the sulfur atoms, for metals like Mo(O), Co(I), or Rh(I), generating complexes with a variety of ge0metries.l Moreover, the metal-sulfur bond is not labile in these complexes, an unexpected result considering that the sulfur atom in the thiophene ring is a weak nucleophile.2 We have proposed that the tenacity of this bond is the consequence of constraints imposed by the short ethylene chain between the phosphorus atom and the thiophene ring. In this study, our goal was to develop a new class of polydentate ligands with weak metal-ligand bonds which may be cleaved reversibly to open a coordination site on the metal to induce catalytic activity. This property is observed for some polydentate ligands that combine phosphorus with oxygen donor atoms.3 For this reason, we decided to extend the length of the chain between the phosphorus atom and the thiophene ring and turned to the synthesis of 2,5-bis[3-(diphenylphosphino)propyl]thiophene (2). In this paper, we relate the synthesis of ligand 2 and the results concerning the evaluation of its bonding Abstract published in Advance ACS Abstracts, November 15,1994. (1)Alvarez, M.;Lugan, N.; Mathieu, R. Znorg. Chem. 1993,32,5652. (2)(a) Angelici, R. J. Acc. Chem. Res. 1988,21,387. (b) Angelici, R. J. Coord. Chem. Rev. 1990,105,27.(c) Rauchfuss, T.B. Prog. Znorg. Chem. 1991,39,259. (3)Bader, A.; Lindner, E. Coord. Chem. Rev. 1991,108, 27. @
properties toward Rh(I), which show that this lengthening induces, as expected, a weakening of the Rh-S bond and allows ligand 2 to use q2 to v7 modes of bonding t o the Rh(1)center. The evaluation of the catalytic activity of similar complexes of Rh(1) with ligands 1 and 2 toward hydroformylation of l-hexene is also presented.
Results and Discussion (a) Synthesis of 2,5-Bis[3-(diphenylphosphino)propyllthiophene. Ligand 2 is synthesized in four steps from 24ithiothiophene, as shown in Scheme 1.In the first step, the 2-lithio salt reacts with l-bromo-3chloropropane, leading t o 2-(3-~hloropropyl)thiophene. In the second step, reaction with PPhzLi allows the isolation of 2-13-(diphenylphosphino)propyllthiophene. Subsequent reactions with BuLi and l-bromo-3-chloropropane lead to the formation of 2-13-(diphenylphosphino)propyll-5-(3-chloropropyl)thiophene,whose reaction with PPhzLi leads t o ligand 2, an air-stable white powder, with 49% overall yield from the starting thiophene. Evaluation of the Bonding Modes of 2 in Cationic Rh(1)Complexes. To have a direct comparison with ligand 1, we have continued t o use the family of cationic complexes [Rh(COD)Lzl+, which are easily obtained and which are good starting materials for the synthesis of carbonyl derivative^.^ (4)Schrock, R.R.;Osborn, A. J. J.Am. Chem. SOC.1971,93,2397.
0276-733319512314-0365$09.00/0 0 1995 American Chemical Society
366 Organometallics, Vol. 14, No. I , 1995
Alvarez et al. Scheme 1
When (COD)Rh(acac)is treated in THF with a slight excess of perchloric acid (see safety note below) and then with 1 equiv of 2, immediate formation of a yellow precipitate, 3, is observed. This complex is insoluble in all common solvents, suggesting a polymeric structure. This insolubility precludes any NMR measurements, but chemical analysis is consistent with the formula {[Rh(COD)(2)1[C1041}. for 3. When a suspension of 3 in dichloromethane is saturated with carbon monoxide, the yellow solid gradually disappears, giving a yellow solution. Monitoring the reaction by infrared spectroscopy shows the presence of a weak band at 2072 cm-l and of two strong bands at 2030 and 2013 cm-l. This spectrum is very similar t o the spectrum of [Co(CO)3(1)1+ and is consistent with a trigonal-bipyramidal structure in which the asymmetry of the ligand induces the splitting of the E mode expected for a D3h symmetry group for the molecule and a weak activity for the infrared-inactive A 1 mode of v i b r a t i ~ n .This ~ hypothesis is confirmed by the 31P{1H} NMR spectrum of the same solution: a doublet is observed at 28.7 ppm (J(Rh-P) = 80.5 Hz), with a coupling constant characteristic of [Rh(C0)3(PR3)21+ complexes! Moreover, the lH NMR spectrum shows, besides the resonances due t o free 1,5-cyclooctadiene,a singlet at 6.79 ppm due to the protons of the thiophene ring and three multiplets due to the methylene groups. From these observations we propose that the action of carbon monoxide has induced the transformation of 3 into [Rh(CO)~(2)1[C1041(4) in which the two phosphorus atoms are in the axial positions of a trigonal bipyramid. In order to evaluate the possible modes of bonding of ligand 2, the solution of 4 was decarbonylated either by bubbling nitrogen into the solution or by evaporating the solvent under vacuum. Initial results showed that several products were present, depending the reaction conditions. This decarbonylation reaction was analyzed by the simultaneous use of IR and NMR spectroscopies at different stages of decarbonylation. M e r the solvent from the solution of 4 has been evaporated under vacuum, IR spectroscopy of the residue shows the presence of two strong absorptions at 2035 and 2020 cm-l and one of medium intensity a t 1993 cm-l. The 31P{1H} NMR spectrum shows the presence of three complexes in about a 1:l:l ratio, with (5)Adams, D.M. Metal-Ligand and Related Vibrations; Edward Arnold Ltd.: London, 1967; p 105. (6) Lindner, E.; Wang, Q.; Mayer, H. A.; Fawzi, R.; Steimann, M. Organometallics 1993,12, 1865.
a doublet a t 26 ppm (J(Rh-P) = 133 Hz) (5), a doublet a t 23 ppm (J(Rh-P) = 106 Hz) (6), and a doublet at 20 ppm (J(Rh-P) = 110 Hz) (7). Renewed evaporation of the solution and its prolonged standing under vacuup lead to a new mixture characterized in IR spectroscopy by a strong band at 2020 cm-1, a weak band a t 2035 cm-l, and a medium intensity band at 1993 cm-l. The 31P{1H}NMR spectrum shows that only two complexes 5 and 7 are present, 7 being the major product. To complete the decarbonylation reaction, the dichloromethane solution was refluxed for 1 h. In the IR spectrum only the absorption at 2020 cm-l remains, and in the 31P{1H} NMR spectrum 7 is still present but a new resonance is observed: a doublet at 33 ppm (J(RhP) = 205 Hz) (8). Prolonged heating of the solution or refluxing in acetone leads to the complete disappearance of 7 and to the unique presence of 8 , which shows no IR absorption in the CO stretching region. Bubbling carbon monoxide through a solution of 8 in dichloromethane regenerates complex 4. These observations show that ligand 2 has a greater flexibility than ligand 1in its coordination to rhodium(I) and that the lengthening of the methylene chain between the phosphorus and the thiophene ring has allowed a situation where only the two phosphines are bound to the metal (e.g., complex 41, a situation not encountered with complexes of ligand 1. The similarity of the spectroscopic data for complex 7 (v(C0) = 2020 cm-l, 6 31P= 20 ppm, J(Rh-P) = 110 Hz)and that for the complex [Rh(CO)(l)ICC1041(v(C0) = 2020 cm-l, 6 31P = 8.3 ppm, J(Rh-P) = 111.6 Hz)' indicates that these complexes have similar structures: 7 is a square-planar complex, the ligand being tridentate through the two phosphines and the sulfur atom of the thiophene ring and the carbonyl group being trans to the sulfur atom. The identification of the complexes 5 and 6 is less straightforward, but information can be derived from the chronology of their formation and from their spectroscopic data. As they appear during the first steps of the decarbonylation of 4 and disappear during the formation of 7, a monocarbonyl complex, they can be identified as dicarbonyl complexes. On this basis, the characterization of 6 is straightforward as this complex gives one IR absorption at 2035 cm-l and its 31P{1H} NMR spectrum shows a coupling constant of J(Rh-P) = 106 Hz. These data are similar to the data observed for the [Rh(CO)2(PR3)2]+complexes with a square-planar
2,5-Bis[3-(diphenylphosphino)propyllthiopheneBonding with Rh(I)
Organometallics,Vol.14,No.1, 1995 367
Table 1. Selected Bond Lengths (A) and Angles (deg) for rmmirBPbi ( to Bond Lengths 2.235(2) C(3)-C(4) 2.504(3) C(4)-C(5) 2.221(7) C(5)-C(6) 2.275(6) C(6)-C(7) 2.307(7) P(2)-C( 10) 2.251(2) P(2)-C(3 1) 2.261(8) P(2)-C(41) 1.832(9) C(7)-C(8) 1.826(8) C(8)-C(9) 1.83(1) C(9)-C( 10) 1.763(7) B(l)-C(51) 1.724(7) B( 1)-C(61) 1.50 (1) B(l)-C(71) 1.49(2) B(l)-C(81)
Figure 1. ORTEP drawing of the cationic part of 8' showing the numbering scheme.
structure and in which the CO ligands are in trans position6 In this situation, the ligand 2 is v2 bound to rhodium by the two phosphorus atoms in trans positions. Complex 5 is characterized by two IR-active bands a t 2035 and 1993 cm-l, which is consistent with a cis dicarbonyl complex. However, the value of the coupling constant J(Rh-P) = 133 Hz in its 31P{1H} NMR spectrum excludes a situation in which ligand 2 is v3 bound. Indeed, for the [Rh(CO)z(l)I+complex J(RhP) = 90.3 Hz' and similar low J(Rh-P) values are also observed for other pentacoordinated [Rh(CO)z(PR&I+ compound^,^ but in the case of [Rh(CO)z(diphos)l+ compounds J(Rh-P) values of 120 Hz are observed.8 We thus propose for 5 a square-planar structure in which the ligand 2 is v2 bound to rhodium by the two phosphorus atoms in cis positions. These results demonstrate further that 2 is a very flexible ligand. The completely decarbonylated complex has been fully characterized by an X-ray crystal structure determination on crystals of 8' obtained after replacing the perchlorate anion by the tetraphenylborate anion. A perspective view of the molecule is given in Figure 1 along the labeling scheme. Bond lengths and angles of interest are gathered in Table 1. It appears that the lengthening of the carbon chain between the phosphorus and the thiophene ring in ligand 2 has allowed the ring to participate in 7~ bonding, leading to a structure similar to that observed for the complex [Rh(115-C5H4S)(PPh3)~1[PFsI.9 Comparison of bond lengths between the two structures shows that the main effect of the presence of the propyl chain between thiophene and the phosphorus atoms is the shortening of the rhodium-sulfur bond (2.567(3) A in [Rh(v5C5H4S)(PPh3)2][PFs]). This is likely to be due t o an electronic effect of the substituents on the ring, as in (7) Johnston,G. G.; Baird, M. C. Organometallics 1989,8, 1894. (8)Fairlie, D. P.; Bosnich, B. Organometallics 1988,7 , 936. (9)Sanchez-Delgado, R.A.; Marquez-Silva, R. L.; Puga, J.; Tiripicchio, A.; Tirripichio Camellini, M. J.Organomet. Chem. 1988,316,C35.
P( 1)-Rh( 1)-P(2) Rh( l)-P( 1)-C( 1) Rh(1)-P(1)-C(l1) C(l)-P(l)-C(ll) Rh(1)-P(1)-C(21) C(1)-P(1)-C(21) C(ll)-P(l)-C(21) C(4)-S( 1)-c(7) P( 1)-C( 1)-C(2) C( 1)-c(2)-c(3) C(2)-C(3)-C(4) Rh( l)-C(4)-C(3) S( l)-c(4)-c(3) S(l)-C(4)-C(5) C(3)-C(4)-C(5) C(4)-C(5)-C(6) C(5)-C(6)-C(7) Rh( l)-P(2)-C( 10)
Bond Angles 99.49(7) Rh( l)-P(2)-C(3 1) 109.7(3) C(lO)-P(2)-C(31) 121.6(3) Rh(l)-P(2)-C(41) 102.0(4) C(lO)-P(2)-C(41) 115.0(3) C(31)-P(2)-C(41) 102.1(5) S(l)-C(7)-C(6) 104.2(4) Rh(l)-C(7)-C(8) 92.0(4) S(l)-C(7)-C(8) 117.1(7) C(6)-C(7)-C(8) 118.0(10) C(7)-C(8)-C(9) 115.7(8) C(8)-C(9)-C(lO) 125.1(6) P(2)-C(lO)-C(9) 126.8(7) C(51)-B(l)-C(61) 103.4(5) C(51)-B(l)-C(71) 128.2(8) C(61)-B(l)-C(71) 120.6(7) C(51)-B(l)-C(81) 110.0(7) C(61)-B(l)-C(81) 107.4(3) C(71)-B(l)-C(81)
1.48(1) 1.413(7) 1.306(8) 1.394(8) 1.832(7) 1.836(7) 1.818(7) 1.47(1) 1.51(1) 1.52(1) 1.64(1) 1.66(1) 1.65(1) 1.66(1) 118.2(2) 101.1(3) 119.9(2) 102.3(3) 105.2(3) 111.3(6) 128.0(6) 125.6(6) 121.6(7) 114.5(7) 114.4(8) 113.9(6) 109.6(6) 108.5(6) 111.9(6) 111.2(6) 108.3(6) 107.3(6)
Estimated standard deviations in parentheses.
the (~5-2,5-dimethylthiophene)(cyclooctadiene)Rhl~BF~l compound recently described,1° where the rhodiumsulfur bond length (2.467(3)A) is similar to the length found in our complex. In conclusion, this study of the reactivity of 3 toward carbon monoxide provides evidence for the great flexibility of ligand 2. The longer carbon chain between the phosphorus atoms and the thiophene ring allows, compared to ligand 1,ligand 2 to accommodate situations in which it can be either bidentate through the two phosphorus atoms in cis or trans positions on a square. planar complex or hexadentate through ~ tcoordination of the thiophene ring and coordination of the two phosphorus atoms. Like ligand 1 , 2 can also be tridentate through the two phosphorus and the sulfur atom of the thiophene ring. These observations are summarized in Scheme 2. To determine whether the different bonding capabilities of ligands 1 and 2 have some impact on the catalytic activities of their complexes, we checked the behavior of complexes [Rh(COD)(1)I[C1041(9)and [Rh(COD)(B)I[C1041(3)as catalysts in the hydroformylation of l-hexene. Under the same reaction conditions (20 bar of a 1:1 COB2 mixture, l-hexenehatalyst ratio of 200, 3NEt3/Rh, CHzClz as solvent), which have not been optimized, after 6 h at 50 "C, 39% conversion of l-hexene is observed with complex 9 as catalyst and 88% with complex 3. The linearhranched ratio for the resulting aldehydes is 2.2 in the first case and 2.6 in the second case (mean of two experiments). From these results, it appears that the substitution of ligand 1 by the more (10)Polam, J. R.;Porter, L. C. Organometallics 1993,12,3504.
368 Organometallics, Vol. 14, No. 1, 1995
Alvarez et al. Scheme 2
4
1
6
$+'
5
-co
1+
p/Rh\p
I
8
Table 2. Expreimental Data for the X-ray Study of 8'eMezCO
labile ligand 2 increases the efficiency of the catalyst by a factor greater than 2.
Experimental Section All reactions were performed under a nitrogen atmosphere with use of standard Schlenk techniques. Elemental analyses were performed in our laboratory for C, H, and S. PPhzH" and (COD)Rh(acac)12have been prepared according to published procedures. Safety Note! Perchlorate salts of metal complexes with organic ligands are potentially explosive. Only small amounts of material should be prepared, and these should be handled with great caution. Synthesisof the 2,5-Bis[3-(diphenylphosphino)propyllthiophene Ligand 2. This compound was synthesized in four steps from thiophene. (a) Synthesis of the 2-(3-Chloropropyl)thiophene.To a stirred solution of 4 mL (49.9 mmole) of thiophene in 20 mL of THF at -60 "C was slowly added 31.25 mL (50mmol) of a solution of BuLi, 1.6 M in hexane. The solution was then stirred and the temperature was raised to -40 "C. Then 4.95 mL of 1-bromo-3-chloropropanewas slowly added. The temperature was increased to room temperature, and the solution was stirred for 15 h. The solvents were then evaporated under vacuum, and the residue was dissolved in 50 mL of diethyl ether. This solution was washed two times with 50 mL of water, and the ether solution was then dried over sodium sulfate. After filtration of the ether solution and elimination of ether under vacuum, 6.18 g of 2-(3-~hloropropyl)thiophene was recovered as a pale yellow oil (77%) which was used without further purification. 'H NMR (CDC13 solution, 200 MHz): 7.18 (m, lH), 6.93 (m, lH), 6.84 (m, lH), 3.57 (t, J = 6.4 Hz, 2H), 3.02 (t,J = 6.4 Hz, 2H), 2.13 ppm (9,J = 6.4 Hz, 2H). (b)Synthesis of the 2-[3-(Diphenylphosphino)propyl]thiophene. To the 6.18 g of 2-(3-~hloropropyl)thiophene (38.5 mmol) dissolved in 50 mL of THF was slowly added at 0 "C PPhzLi (synthesized from 38.5 mmol of PPhzH and 38.5 mmol of BuLi in 37 mL of THF). The solution was stirred for 2 h and then evaporated to dryness under vacuum. The residue was dissolved in 50 mL of diethyl ether, and the solution was washed two times with 50 mL of water and then dried over sodium sulfate. After filtration of this solution and evaporation of the solvent, recrystallization of the residue from methanol led to 10.75g of the product as a white powder (90%). 'H NMR (CDC13solution, 200 MHz): 7.43-7.29 (m, lOH), 7.10 (11)Gee, W.; Shaw, R. A.; Smith, B. C. Inorg. Synth. 1967,9, 19. (12) Sinou, D.;Kagan, H. B. J. Organomet. Chem. 1976,114,325.
formula fw crystal system space group a, A
b, 8,
A B. deg C,
v, A 3
L
C6lH&OPzRhS 1016.88 monoclinic C2h5-P21/n 1 1.26l(2) 15.886(4) 28.986(4) 96.70(2) 5149(2) 4 1.312 22 Mo Ka, A(Mo Kal) = 0.7093 8, 4.649 0.98-1.0 w/2e 2-48
radiation linear abs coeff, cm-I absorption correction, min-max scan mode 28 l i t , deg no. of unique data used in final refinement, Fa2 > 3a(Fa2) 4254 final no. of variables 594 R (on Fo, Faz> ~ U ( F , ~ ) ) ~ 0.0527 Rw (on Fa,Fa2> ~ U ( F ~ ~ ) ) ~ 0.0586
R = CllFO - lFcl~/~lFal. Rw = [h~(lF., - IFcl)z/(~wl~alz)11'2, unit weights.
(m, lH), 6.89 (m, lH), 6.75 (m, lH), 2.95 (t, J = 7.2 Hz, 2H), 2.13 (m, 2H), 1.86 ppm (m, 2H). 31P{1H) "R (CDCl3solution, 32.4 MHz): -17.5 ppm. (c) Synthesis of 2-[3-(Diphenylphosphino)propyll-5-(3chloropropy1)thiophene. To the 10.75 g of 2-[3-(diphenylphosphino)propyl]thiophene (34.6 mmol) in 50 mL of THF cooled at 0°C was slowly added 21.6 mL (34.6 mmole) of 1.6 M BuLi, and the solution was stirred for 1h at this temperature. To this solution was slowly added 3.4 mL of l-bromo3-chloropropane (34.6 mmol). The solution was stirred for 2 h at 0 "C and then for 2 h at room temperature. The solvents were removed under vacuum and the residue was dissolved in 50 mL of diethyl ether. The solution was washed with 2 x 50 mL of water and then dried over sodium sulfate. After filtration of this solution and evaporation of the solvent under vacuum 12.72 g of a yellow oil was obtained (95%). lH NMR (CDCl3 solution, 200 MHz): 7.53-7.32 (m, lOH), 6.61 (AB system, JAB= 3.1 Hz,#lH), 6.57 (AB system, JAB= 3.1 Hz, lH), 3.57 (t, J = 6.4 Hz, 2H), 2.97 (t,J = 7.1 Hz, 2H), 2.90 (t, J = 7.4 Hz, 2H), 2.13 (m, 4H), 1.83ppm (m, 2H). 31P{'H} "R (CDC13 sol., 32.4 MHz): -16.7 ppm. (d) Synthesis of 2. To the 12.72 g of 2-[3-(diphenylphosphino)propyl]-5-(3-chloropropyl)thiophene (32.9 mmol) dissolved in 50 mL of THF and cooled to 0 "C was slowly added 32.9 mmol of PPhzLi in 36 mL of THF (synthesized from
2,5-Bis~3-(diphenylphosphino)propyllthiophene Bonding with Rh(I)
Organometallics, Vol. 14,No. 1, 1995 369
PPhzH and BuLi). The solution was stirred for 2 h at room ppm (m, 4H). 31P{1H}N M R (CD2C12solution, 32.4 MHz): 28.7 temperature and then the THF was eliminated under vacuum. ppm, (J(Rh-P) = 80.5 Hz. The residue was dissolved in 50 mL of diethyl ether, and the Synthesis of [Rh(2)1[C1041 (8). See safety note above. solution was washed with 2 x 50 mL of water. The solution This reaction was conducted in the same way as for 4 except was dried over magnesium sulfate. f i r filtration of this than at the end of the reaction the solution was evaporated to solution and elimination of the solvent under vacuum, recrysdryness. The residue was dissolved in 15 mL of acetone, and tallization of the residue from methanol gave 13.15 g (74.5%) the solution was refluxed for 45 min. The product was of 2 as white crystals. lH NMR (CDC13 solution, 200 MHz): recrystallized from an acetonekexane mixture giving 0.18 g 7.44-7.24(m,2OH),6.51(~,2H),2.85(t, J = 7.2Hz,4H),2.10 of 8 as orange crystals (80%). lH NMR (CD2C12 solution, 200 (m, 4H), 1.79 ppm (m, 4H). 13C{lH} NMR (CDCl3 solution, MHz): 7.27-7.24 (m, 20H), 6.53 (s,2H), 2.72 (m, 4H), 2.0 (m, 20.1 MHz): 141.7 (C(2),C(5),C&S), 138.1 (d, J(P-C) = 13.2 4H), 1.69 ppm (m, 4H). 13C{'H} NMR (CDCls solution, 20.1 Hz, Ph), 132.1 (d, J(P-C) = 18.5 Hz, Ph), 128 (Ph), 127.7 (C(3), MHz): 136.2, 135.2 (m), 133.5 (m), 130.7 (m), 128.4 (m), 125.8 C(4), C4H2S), 123.3 (Ph), 30.8 (d, J(P-C) = 13.5 Hz, CH2(m), 122(Ph), 100.5 (d, J(Rh-C) = 4.7 Hz, C(2), C(5), C~HZS), ) , (d, J(Rh-C) = 3.5 Hz, C(3), C(4),C4H2S), 27.7 (t, J(P-C) C H Z C H ~ P P 27.3 ~ ~ ) ,(d, J(P-C) = 17 Hz, C H ~ C H Z C H ~ P P ~ ~ 99.1 26.8 ppm (d, J(P-C) = 11.8 Hz, C H Z C H ~ C H ~ P P31P{1H} ~~). = 14.6 Hz, C H ~ C H ~ C H ~ P 27.3 P ~ Z(9, ) , C H ~ C H Z C H Z P P24.3 ~~), N M R (CDCls solution, 32.4 MHz): -16.9 ppm. Anal. Calcd ppm (t, J(P-C) = 2.7 Hz, CH2CHzCH2PPh2). 13CN M R (CDCl3 for C~J-IMP~S: C, 76.10; H, 6.39; S, 5.97. Found: C, 75.82; H, solution, 20.1 MHz): 99.1 (dd, J(Rh-C) = 3.5 Hz, J(C-H) = 6.18; S, 5.85. 180 Hz; C(3),C(4),C4H2S). 31P{lH} NMR (CDC13solution, 32.4 MHz): 33.8 ppm, J(Rh-P) = 205 Hz. Anal. Calcd for Synthesis of { [(COD)Rh(2)][C104]}, (3). See safety note C&34ClO&RhS: C, 55.26; H, 4.64; S, 4.34. Found: C, 55.32; above. To 0.3 g (1 mmol) of (COD)Rh(acac)dissolved in 3.5 H, 4.85; S, 4.12. mL of THF was added 0.99 mmol of HC104. This solution was stirred for 15 min and then 0.505 g (0.94 mmol) of 2 dissolved Synthesis of [Rh(2)l[BP4] (8'). See safety note above. To in 6 mL of THF was added, and the solution was stirred for 2 a solution of 0.17 g of 8 in 3 mL of dichloromethane was added h. A yellow precipitate appeared, and the solution was then 0.118 g of NaBPk dissolved in 3 mL of methanol. The solution filtered. The precipitate was washed with acetone and dried was stirred for 30 min at room temperature and then evapounder vacuum; 0.637 g of 3 as a yellow powder was isolated rated to dryness. Recrystallization from an acetonekexane (80%). Anal. Calcd for C42H&104P2RhS: C, 59.57; H, 5.48; mixture gave 0.17 g of 8' as orange crystals. Anal. Calcd for S, 3.79. Found: C, 59.60; H, 5.52; S, 3.91. 8'.(CH&CO: CsiHsoBOPzRhS: C, 72.05; H, 5.95; S, 3.15. Found: C, 71.96; H, 5.97; S, 3.35. Synthesis of [(CO)aRh(2)][C1041 (4). See safety note above. Carbon monoxide was bubbled for 30 min through a Catalytic Experiments. All catalytic runs were performed suspension of 0.25 g of 3 in 10 mL of dichloromethane. The in a home-built stainless steel autoclave equipped with gas solid rapidly dissolved giving a yellow solution. 4 was unstable and liquid inlets, a heating device, and magnetic stirring. Gas in the absence of CO and was characterized by IR + NMR chromatography analyses were performed on an Intersmat IGC 120 FL gas chromatograph,with flame ionization detector, spectroscopy. IR v (CO)(CH2C12 solution): 2072 (w), 2030 (s), fitted with a 3 m x l/g in. column (10% Carbowax 20M in 2013 (s) cm-'. 'H NMR (CDZC12 solution, 200 MHz): 7.907.30 (m, 20H), 6.79 (s, 2H), 3.57 (m, 4H), 2.72 (m, 4H), 1.88 Chromosorb W 80/100 mesh), and using N2 as carrier gas. Table 3. Fractional Atomic Coordinates and Isotropic or Equivalent Temperature Factors atom
(I
xla 0.12981(5) 0.2338(2) 0.1719(2) 0.3302(9) 0.277( 1) 0.2562(9) 0.1635(6) 0.0409(5) -0.0295(7) 0.0883(1) 0.0320(6) -0.0294(9) 0.0053(9) -0.0261(7) 0.4526(8) 0.5288(9) 0.493(1) 0.380( 1) 0.303l(9) 0.3386(7) 0.196(1) 0.129(1) 0.007(1) -0.047( 1) , 0.022(1) 0.1442(9) 0.1827(7) 0.2706(8) 0.3829(8) 0.4085(8) 0.3198(7) 0.2057(6) 0.066 l(8) 0.008(1)
Ylb 0.7405(1) 0.9963(2) 0.7413(7) 0.7737(8) 0.8659(8) 0.9014(5) 0.8801(5) 0.9170(5) 0.8629(1) 0.9810(5) 1.0390(6) 1.0287(5) 0.9437(5) 0.7414(8) 0.7206(9) 0.6695(8) 0.6404(7) 0.6596(5) 0.7107(5) 0.5679(6) 0.4971(7) 0.5032(7) 0.5807(6) 0.6507(6) 0.6460(6) 0.9130(5) 0.941 l(5) 0.9548(6) 0.9410(7) 0.9119(6) 0.8985(4) 0.732 l(5) 0.6637(6)
Estimated standard deviations in parentheses.
dc
UCqb
0.09712(7j 0.0569(1) 0.0504(3) 0.0038(4) -0.0013(3) 0.0252(2) 0.0220(2) 0.0485(3) 0.16990(6) 0.074 l(3) 0.1032(3) 0.1548(3) 0.1739(3) 0.1535(3) 0.1922(4) 0.2248(4) 0.2205(3) 0.1814(3) 0.1473(3) 0.0829(4) 0.0720(4) 0.0637(5) 0.0629(4) 0.0738(4) 0.0838(3) 0.2600(3) 0.2932(3) 0.2815(3) 0.2372(3) 0.2045(3) 0.2150(2) 0.2348(3) 0.2520(3)
0.0407 0.0491 0.0780 0.0728 0.0868 0.0800 0.0536 0.0392 0.0564 0.0372 0.0607 0.0725 0.0639 0.0525 0.0765 0.0935 0.0886 0.0782 0.0659 0.0514 0.0784 0.0892 0.0955 0.0920 0.0809 0.0694 0.0509 0.0601 0.0694 0.0725 0.0616 0.0436 0.0560 0.0710
Uc, = '1s trace U .
atom
xla -0.0954(9) -0.1392(8) -0.0820(7) 0.0221(6) 0.4001(8) 0.6149(7) 0.6952(7) 0.6619(8) 0.5455(9) 0.4638(8) 0.4957(7) 0.4017(7) 0.3788(8) 0.3354(7) 0.3 128(7) 0.3355(7) 0.3795(6) 0.5194(8) 0.5653(9) 0.5474(9) 0.4828(8) 0.4368(7) 0.4519(6) 0.2597(8) 0.1533(9) 0.05lO(8) 0.0546(7) 0.1613(7) 0.2690(7) 0.793(1) 0.739(1) 0.701(2) 0.718(1)
Ylb 0.6338(6) 0.6709(6) 0.7387(5) 0.77 12(4) 0.2440(6) 0.2005(5) 0.1453(6) 0.0672(5) 0.0445(5) 0.1007(5) 0.1808(4) 0.1322(5) 0.1053(6) 0.1610(6) 0.2416(6) 0.2672(5) 0.2138(5) 0.3801(5) 0.4606(6) 0.5058(6) 0.4702(6) 0.3900(5) 0.34 12(4) 0.2304(6) 0.2380(6) 0.2564(6) 0.2680(6) 0.2606(5 ) 0.2426(5) 0.4186(9) 0.4095(8) 0.327( 1) 0.4656(8)
(A2x
lOOyl
dc 0.2286(3) 0.1874(3) 0.1705(3) 0.1944(2) 0.07 1l(3) 0.1 118(3) 0.1353(3) 0.1483(3) 0.1376(3) 0.1 147(3) 0.1007(2) 0.0013(2) -0.0440(3) -0.0782(3) -0.0661(3) -0.0198(3) 0.0160(3) 0.0451(3) 0.0524(4) 0.0906(4) 0.1225(4) 0.1144(3) 0.0768(3) 0.1387(3) 0.1584(3) 0.1301(4) 0.0836(4) 0.0636(3) 0.0917(3) 0.1656(5) 0.2100(5) 0.2 19l(7) 0.2345(5)
Ucqb
0.0685 0.0647 0.0537 0.0408 0.0476 0.0503 0.0654 0.0603 0.0634 0.0595 0.0414 0.05 14 0.0657 0.0589 0.0618 0.0539 0.0473 0.0628 0.0787 0.0722 0.0683 0.0582 0.0448 0.067 1 0.0711 0.0706 0.0693 0.0553 0.0494 0.1046 0.0971 0.1727 0.1604
370 Organometallics, Vol. 14,No. 1, 1995 Mesitylene was used as internal standard. The experimental conditions were as follows: 1-hexene (20 mmol), the complex (0.1 mmol), CHzClz (16 mL), mesitylene (1.5 mL), NEts (0.04 mL), Hz (10 atm), and CO (10 atm), 50 "C. X-ray Diffraction Studies. Crystals of 8' suitable for X-ray diffraction were obtained through recrystallization from hexane/acetone solutions at 0 "C. Data were collected on an Enraf-Nonius CAD4 diffractometer at 22 "C. Cell constants were obtained by the least-squares refinement of the setting angles of 25 reflections in the range 24" < 20(Mo Kal) 28". The space group was determined by careful examination of systematic extinctions in the listing of the measured reflections. Data reductions were carried out using the CRYSTALS crystallographic computing package.13 The intensities were corrected from absorption by using DIFABS program.l* Table 2 presents further crystallographic information. The structures were solved by using SHEIXS-86 program,15 which revealed the position of Rh, S, and P atoms. All remaining non-hydrogen atoms were located by the usual combination of full-matrix least-squares refinement and difference electron density syntheses by using the CRYSTALS program.13 A molecule of acetone for each molecule of 8' was (13)Watkin, D. J.;Carruthers, J. R.; Betteridge, P. W. CRYSTALS, An Advanced Crystallographic Program System; Oxford, U.K, 1988. (14)Walker, N.;Stuart, D. Acta Crystallogr. 1983,39, 158.
Alvarez et al. found in the crystal lattice. Atomic scattering factors were taken from the usual tabulations.16 Anomalous dispersion terms for Rh,S, and P atoms were included in F,.l7 All nonhydrogen atoms were allowed to vibrate anisotropically. All the hydrogen atoms were set in idealized position (C-H = 0.98 A). Scattering factors for the hydrogen atoms were taken from Stewart et al.lS Final atomic coordinates for non-hydrogen atoms are given in Table 3.
Supplementary Material Available: Table S1, anisotropic thermal parameters for 8 , and Table ,632, hydrogen positions for 8' (4 pages). Ordering information is given on any current masthead page. OM940456N (15)Sheldrick, G. M.SHELXS-86, Programm for Crystal Structure Solution; University of Gattingen: Gattingen, Federal Republic of Germany, 1986. (16)Cromer, D. T.; Waber, J. T. International Tables for X-ray Crystallography; Kynoch Press: Birmingham, England, 1974;Vol. 4, Table 22B. (17)Cromer, D. T.; Waber, J. T. In International Tables for X-ray Crystallography; Kynoch Press: Birmingham, England, 1975;Vol. 4, Table 2.3.1. (18)Stewart, R. F.; Davidson, E. R.; Simpson, W. T. J.Chem. Phys. 1966,42,3175.
