Organometallics 1992,11, 2767-2774
2767
Table 111. Metal Valence Populations"for ScCp,+ in Different Geometriesb ~ C p s c C p deg ,
180 160
s 0.134 0.133
Pr 0.016 0.015
PY 0.016 0.012
" Natural population analysis was employed."
"he
PI 0.003 0.004
dry
0.005 0.015
d.?, 0.379 0.377
dY2 0.379 0.382
d r ~ y+ 2 d,z 0.062 0.100
d, 0.826
0.874
y t plane contains the C p ring midpoints and the metal.
ter-ring repulsion. This will also contribute to the more bent structures for the MCp,+ cations studied here compared to the neutral MCp, systems.
Acknowledgment. This work was supported by the Deutache Forschungsgemeinschaft, the Fonds der Chem-
ischen Industrie, the Stiftung Volkswagenwerk, and Convex Computer Corp. M.K. acknowledges a KBkulB scholarship by the Fonds der Chemischen Industrie. We also thank Prof. H. Stoll (Stuttgart, Germany) for valuable suggestions. OM9202377
Articles Unusual Low-Valent Dirhodium Complexes Bridged by Bls(dimethy1phosphino)methane Ligands James A. Jenkins and Martin Cowie' Chemistry Depertment, University of Alberta, Edmonton, Albem, Canada T6G 2G2
Received July 20, 1991
The low-valent complex [Rh,(CO),(dmpm),] (1) (dmpm = Me2PCH2PMe2)is prepared by the reaction of tram-[RhCl(CO)(dmpm)j2 with aqueous NaOH and CO. Under a CO atmosphere 1 is in equilibrium with the labile tetracarbonyl species [Rh(CO)(p-CO)(dmpm)],(2). The structure of 1 is believed to be unsymmetrical having a trans arrangement of diphosphine ligands at one metal and a cis arrangement at the other, and a mixed-valence Rh(l+)/Rh(l-) formulation, while 2 is symmetric having the bridging diphosphines cis at both metals, and a corresponding Rh(0) Rh(0) formulation. Reduction of [Rh,C12(CO),(p-RC=CR)(dmpm),] (R = C02Me,CFJ yields [Rh,( O),(p-RC=CR)(dmpm),] (3,4),which can also be obtained by alkyne addition to 1. The alkyne ligands are apparently bound perpendicular to the Rh-Rh axes in both species. Protonation of 1with HBF,.OEt, yields [Rh,(CO),(pH)(dmpm),][BF,], and under carbon monoxide this yields [Rh,(CO),(p-H)(dmpm),] [BF,]. Protonation of 3 yields [Rh2(C0),(cr-DMAD)(p-H)(~lmpm)~] [BF,], whereas protonation of 4 yields [Rh2(CO)2(CF3C-C(H)CF,)(dmpm)2] [BF,], which apparently has a u, *-vinylic moiety. Reaction of this vinyl complex with CO gives [Rh2(C0)3(CF,C=C(H)CF,)(p-CO)(dmpm),][BF,I in which the vinyl group is u bound to only one metal.
L
Introduction Oxidative-addition reactions are of fundamental imp o d c e in organometallicchemistry and are of enormous practical significance since oxidative addition represents one of the key steps in the mechanisms of most homogeneous catalysts.' As the term implies, the oxidative-ad&tion reaction proceeds with an increase in coordination (1)(a)Czlman, J. P.;Hegedus, LS.;Norton, J. R.; FinkLR. G. In Principles and Applications of Organotransition Metal Chemistry; University Science Books: Mill Valley, CA, 1987;Chapter 5. (b) Collman, J. P.; Roper, W. R. Adv. Organomet. Chem. 1968,7,53. (c) Collman, J. P. Acc. Chem. Res. 1968,1,136. (d) Halpern, J. Acc. Chem. Res. 1970, 3,386. (e) Lappert, M. F.; Lednor, P. W. Adu. Organomet. Chem. 1976, 14, 345. (0 Oeborn, J. A. In Organotranaition-Metal Chemistry; Ishii, Y . ;Teuteui, M., Eds.; Plenum: New York, 1975;pp 65-80. (9) Vaska, L. Acc. Chem.Res. 1968,1,335.(h) Ugo, R. Coord. Chem. Rev. 1968,3,319. (i) Cramer, R. Acc. Chem. Res. 1968,1, 186. fi) Parshall, G.W. Acc. Chem. Res. 1970, 3, 139. (k) Deeming, A. J. In MTP International Review of Science, Inorganic Chemistry Series One, Reaction Mechanisms in Inorganic Chemistry; Emeldus, H. J., Tobe, M. L., Eds.; Butterworths. London, 1972;Chapter 4,pp 117-157. (I) Stille, J. K.; Lau, K. S. Y. Acc. Chem. Res. 1978,10, 343. Stille, J. K.In The Chemistry of the Metal-Carbon Bond, Vol. II. The Nature and Cleavage of Metal-Carbon Bonds; Hartley, F. R., Patai, S.,Eds.;Wiley: New York, 1985; pp 625-187.
0276-7333/92/2311-2767$03.00/0
number and oxidation state of the metal center($ involved. Coordinatively unsaturated, electron-rich metal complexes are therefore well suited to such processes. Our recent interest in oxidative-addition reactions2-'' has centered Or Ir (dPPm around dPPm-bidged comPl@xesi n v o l e = bis(dipheny1phosphino)methane) in efforts to obtain an improved understanding about the functions of the adjacent metals in the oxidative-addition step(& about the subsequent ligand rearrangements that occur, and about the possibility of coupling organic fragments on the adjacent metals. It was surmised that low-valent binuclear complexes of Rh(0) or Rh(I), bridged by the closely related (2)Sutherland, B. R.;Cowie, M. Organometallics 1985,4 , 1801. (3)McDonald, R.;Sutherland, B. R.; Cowie, M. Inorg. Chem. 1987,26, 3333. (4)Vaartatra, B. A.; OBrien, K. N.; Eisenberg, R.; Cowie, M. Inorg. Chem. 1988,27,3668. (5)Vaartatra, B. A.; Cowie, M. Inorg. Chem. 1989,28,3138. (6)McDonald, R.; Cowie, M. Inorg. Chem. 1990,29,1564. (7)Antonelli, D.M.; Cowie, M. Inorg. Chem. 1990,29,3339. (8) McDonald, R.; Cowie, M. Organometallics 1990,9, 2468. (9)Antonelli, D.M.; Cowie, M. Inorg. Chem. 1990,29,4039. (10)Vaartstra, B.A.; Xiao, J.; Cowie, M. J. Am. Chem. Soc. 1990,112, 9425.
1992 American Chemical Society
2768 Organometallics, Vol. 11, No. 8, 1992
dmpm ligand (dmpm = bis(dimethylphosphino)methane), would be excellent candidates for oxidative additions, owing to the smaller size and increased basicity of dmpm over dppm." Recent chemistry involving the low-valent species [Rh2(CO)3(dppm)z],12-14[Ir2(CO)3(dppm)z],3,8J4 and [RhIr(CO)3(dppm)z]eJ4 had demonstrated a strong tendency of these complexes to oxidatively add substrates such as H2, H2S, thiols, silanes, and alkynes. We therefore undertook an extension of this chemistry to include related low-valent complexes of dirhodium, bridged by dmpm groups. The preparation and characterization of a series of unusual,low-valent binuclear complexes of Rh, utilizing dmpm as the bridging ligand, is reported herein. While this work was in progress, related chemistry involving dmpm-bridged, diiridium complexes was reported.l5J6
Experimental Section General Comments. General experimental conditions are as previously described." Dimethyl acetylenedicarboxylate (DMAD), silver tetrafluoroborate, lithium triethylborohydride, acatyl chloride,thionyl chloride, and tetrafluoroboric acid etherate were purchased from the Aldrich Chemical Co. Concentrated hydrochloric acid was purchased from BDH Chemicals, and sodium borohydride, from Anachemia. Carbon monoxide (CP grade) and dihydrogen were purchased from Matheson, '3cO (99%)from Isotec Inc., and hexafluoro-2-butyne (HFB) from SCM Speciality Chemicals. These and all other reagent grade chemicals were used as received. The compounds trans-[RhC1(CO)(dmpm)12, [Rh2C12(C0)2(p-DMAD)(dmpm)2], and [Rh2C12(C0)2(p-HFB)(dmpmIz] were prepared by the methods described." Preparation of Compounds. (a) [Rh,(CO),(dmpm),] (1). An atmosphere of CO was placed over 100 mg (0.165 mmol) of trans-[RhC1(CO)(dmpm)l2in THF (10 mL) and the resulting orange slurry stirred for 5 min. A 1 M solution of NaOH/H20 (0.33 mL, 0.33 mmol) was then added to the slurry. Complete reaction occurred within 10 to 15 min and was accompanied by dissolution of all solid. After an additional 20 min of stirring, the dark orange solution was placed under vacuum and all solvents were removed. The residue was extracted into benzene or toluene (10 mL) and filtered under dinitrogen through a pad of Celite to provide a clear orange solution. Once again, the solvent was removed under vacuum. At this point the product was recovered as an orange-brown solid or redissolved in THF and reacted further. The isolated yield varied between 65% and 75% (60-70 (11) (a) King,R. B.; RaghuVeer, K. S. Inorg. Chem. 1984,23,2482. (b) Karech, H. H.; Milewski-Mahrla,B. Angew. Chem., Int. Ed. Engl. 1981, 20,814. (c) Karsch, H. H.; Milewski-Mahrla, B.; Besenhard, J. 0.; Hofmann, P.; Stauffert, P.; Albright, T. A. Inorg. Chem. 1986,25,3811. (d) Ling, S. S. M.; Puddephatt, R. J.; MonojlovioMuir,L.; Muir,K. W. Inorg. Chim. Acta 1983,77, L95. (e) Ling, S. S. M.; J o b , I. R.; Manojlovic-Muir, L.; Muir, K. W.; Puddephatt, R. J. Organometallics 1985, 4, 1198. (f) Rankin, D. W. H.; Robertson, H. E.; Karsch, H. H. J. Mol. Struct. 1981, 77, 121. (9) Lisic, E. C.; Hanson, B. E. Inorg. Chem. 1986,25, 812. (h) Lisic, E. C.; Hanson, B. E. Organometallics 1987,6,512. (i) Cotton, F. A.; Falvello, L. R.; Harwood, W. S.; Powell, G. L.; Walton, R. A. Inorg. Chem. 1986,25,3949. (j) Doherty, N. M.; Hogarth, G.; Knox, S. A. R.; Macphereon, K. A.; Melchior, F.; Orpen, A. G. J. Chem. SOC.,Chem. Commun. 1986, 540. (k) Wu, J.; Fanwick, P. E.; Kubiak, C. P. J. Am. Chem. Soc. 1988, 110, 1319. (1) Kullberg, M.L.; Lemke, F. R.; Powell, D. R.; Kubiak, C. P. Inorg. Chem. 1985,24,3589. (m) Kullberg, M. L.; Kubiak, C. P. Inorg. Chem. 1986, 25, 26. (n) Wu, J.; Fanwick, P. E.; Kubiak, C. P. J. Am. Chem. Soc. 1989, 111, 7812. ( 0 ) Manojlovic-Muir, L.; Ling, S. S. M.; Puddephatt, R. J. J. Chem. SOC.,Dalton Trans. 1986, 151. (12) (a) Wang, W.-D.; Hommeltoft, S. I.; Eisenberg, R. Organometallics 1988, 7, 2417. (b) Wang, W. D.; Eisenberg, R. J.Am. Chem. SOC.1990, 112,1833. (13) Berry, D. H.; Eisenberg, R. J. Am. Chem. SOC.1985,107, 7181. (14) McDonald, R.; Cowie, M. Manuscript in preparation. (15) (a) Wu, J.; Fanwick, P. E.; Kubiak, C. P. J. Am. Chem. SOC.1988, 110,1319. (b) Wu,J.; Fanwick, P. E.; Kubiak, C. P. J. Am. Chem. SOC. 1989,111,7812. (16) Reinking, M. K.; Ni. J.; Fanwick, P. E.; Kubiak, C. P. J. Am. Chem. SOC. 1989,111,6459. (17) Jenkins, J. A.; Ennett, J. P.; Cowie, M. Organometallics 1988, 7,
1845.
Jenkins and Cowie mg). This complex proved to be a nonelectrolyte in THF (A M) = 0.67 Q-' cm2 Anal. Calcd for C13Hze03P,Rh2:C, 27.8; H, 5.0. Found: C, 27.9; H, 4.8. Due to the extreme hygroscopic nature of compound 1, fresh samples were required for suitable elemental analyses. (b)[Rh(CO)(p-Co)(dm~m)]~ (2). A solution of codpound 1 in THF (5 mL) was prepared in the manner described above using 50 mg (0.083 "01) of trans-[RhC1(CO)(dmpm)l2. Carbon monoxide was bubbled through the solution for 1min at a rate of ca. 0.5 mL/s, resulting in a slight change in the orange color. Variable-temperature '%('H) and 31P(1H)NMR studies in THF-d8 solution showed the tetracarbonyl complex [Rh(CO)(p-C0)(dmpm)12(2) and a small amount of complex 1 to be the only species present. ( c ) [R~,(C!O),(~-DMAD)(~~P~)~] (3). The compound [Rh2Cl2(CO),(pc-DMAD)(dmpm)2] (50 mg, 0.067 mmol) and were placed in an oven-dried Schlenk NaBH4 (10 mg, 0.27 "01) tube under a dinitrogen atmosphere. The addition of 98% EtOH (10 mL) produced a red solution which quickly turned to a deep purple color. After the solutions were stirred for 20 min, the solvents were removed under vacuum, the product was extracted into toluene (10 mL), and the solution was filtered under dinitrogen through a pad of Celite. Compound 3 was isolated in 60 to 70% yield (27-32 mg) as a deep purple solid upon removal of the solvent under vacuum. Storage of the solid overnight under an atmosphere of N2 led to ita decomposition to a dull metallic gray. Subsequent manipulation of the product was carried out in THF, THF-d8, or toluene. Due to ita extreme air sensitivity, suitable carbon and hydrogen elemental analysis results were not obtained. This complex proved to be a nonelectrolyte in THF M) = 0.25 Q-' cm2 mol-'). (A (a) [R~z(CO)Z(~-HFB)(~~P~)~I (4). To [Rh2C12(CO)2(rHFB)(dm~m)~l (50 mg,0.065 "01) in THF (10 mL) was added 2 molar equiv of LiBEGH (0.13 mL of 1M solution in THF). After the solution was stirred for 20 min, the solvent was removed under vacuum, the residue extracted into toluene (10 mL), and the deep purple solution fiitered under dinitrogen through a pad of Celite. The product was isolated in ca. 70% yield (32 mg) as a purple powder upon removal of the toluene under vacuum. Prolonged storage of the solid under a dinitrogen atmosphere led to ita decomposition. Subsequent manipulation of the product was carried out in THF or toluene solution. Due to the extreme air-sensitivityof the solid, reliable carbon and hydrogen elemental analysis results could not be obtained. (e) [Rh2(CO)3(p-H)(dmpm)z][BF4] (5). A solution of [Rh2(CO),(dmpm),] (1) in THF (4 mL) was prepared in the manner described above using 50 mg (0.082 mmol) of trans[RhC1(CO)(dmpm)l2.A 1-equiv amount of HBF4.0Et, (8.3 pL, based on a 70% yield of 1) was added to the solution The reaction was immediate, producing a color change from orange to red and some precipitation of product. Compound 5 was not isolated in solid form due to its facile decomposition. Subsequent characterization of the complex was undertaken spect"pically in THF or THF-d8 solution. (f) [Rh2(CO)4(p-H)(dmpm)Z][BF,] (6). A solution of [Rh2(CO)3(p-H)(dmpm)2][BF4] (5)in THF (4 mL) was prepared in the manner described above using 50 mg (0.082 mmol) of trans-[RhC1(C0)(dmpm)lz. Carbon monoxide was slowly passed through the orange solution at a rate of ca. 0.5 mL/s for 1min, resulting in a change in color to yellow-orange. Variable-temperature 31P('H],'H,and 13C('H]NMR spectroscopy in THF or THF-d8 showed compound 6 to be the only species present after reaction. Passing dinitrogen through the solution regenerated the tricarbonyl complex 5, but the complex rapidly decomposed upon attempts to precipitate a solid. (e) [R~,(CO),(~-DMAD)(~~-H)(~~P~)~I[BFII (7). A solution of [Rh2(CO),(p-DMAD)(dmpm)2] (3) in THF (5 mL) was prepared in the manner described above using 50 mg (0.067 "01) of [Rh,C12(C0)2(p-DMAD)(dmpm)2]. A 1-equiv amount of HBF4-OEt, (6.2 pL, 0.044 mmol based on a 65% yield of 3) was added to the solution. Reaction was immediate, producing a color change from purple to orange with the precipitation of a small amount of orange solid. 31P{1H),'H NMR, and infrared spectroscopy in THF or THF-d8 revealed compound 7 to be the major product. Attempts to isolate the product in solid form resulted in its decomposition.
Low-Valent Dirhodium Complexes
Organometallics, Vol. 11, No. 8,1992 2769
T = 22'C (h) [R~~(CO),(F~CC=C(H)CF~)(~~P~)~I[BF,I (8). The (4) was prepared as decompound [Rh2(CO)2(r-HFB)(dmpm)21 scribed above (using 50 mg (0.065 mmol) of [Rh&1&0)2(p H F B ) ( d m ~ m ) ~and l ) dissolved in toluene (10 mL). To this was added 1equiv of HBFcOEt, (6.5 pL, 0.046 mmol based on 70% conversion of the starting material to complex 3). Upon stirring, the reaction mixture quickly changed color from purple to orange. After 15 min the product settled as an orange-brown oil on the side of the flask. The solvents were removed by cannula under positive N2 pressure, and the oil was dried under vacuum for approximately 15 min. Subsequent manipulation and characterization of the complex was carried out in THF or THF-d8 solution. (i) [R~~(CO)~(F~CC=C(H)CF~)(~-CO)(~~P~)~~[BFII (9). A THF solution (5 mL) of complex 8 was prepared as described above using [~C12(CO)2b-HFB)(dmpm)2] (50 mg,0.067 "01). A stream of CO was then paesed through the solution at the rate -5 -10 -15 -M of ca. 0.2 mL/s for 3 min, producing a color change from orange G(PP~) to yellow followed by the precipitation of a yellow solid. Complete Figure 1. 31P(1H]NMR spectra of [Rh2(CO),(dmpm),] (1) at 22 precipitation of the compound was effected by the addition of and -75 OC. CO-saturated diethyl ether (25 mL) and cooling of the mixture to 0 "C. The solvents were removed by cannula under positive containing an "-OHC1" moiety in which the coordinated N2 pressure, and the product was dried under a slow stream of hydroxide group is hydrogen-bonded to the chloride ion, CO. Recrystallization of this solid from CO-saturated THF/ much as that found in the dppm analogues [Rh,(CO),(pdiethyl ether yielded 37 mg (67%) of compound 9 as a yellow .m The OH.Cl)(dppm),]lg and [Ir,(CO),~-OH~Cl)(dppm),] powder. This complex proved to be a 1:l electrolyte in acetonitrile diiridium species was prepared under similar conditions, (A M) = 164 Q-' cm2 Anal. Calcd for from the reaction of trans-[IrCl(CO)(dppm)], with NaOH, BCl8FloHBO4P4Rhz: C, 25.7; H, 3.5. Found: C, 25.5; H, 3.5. and underwent an analogous transformation yielding Reaction of Complexes with HCl, SOC12, and Acetyl [Irz(CO)3(dppm)z]upon reaction with CO.m Attempts to Chloride. The appropriate reagent (up to 10 molar equiv) was characterize the hydroxide-bridged dmpm analogue of the added via syringe to a solution (THF or toluene) of the complexes, above dppm species met with failure. (11, [Rh2(CO)2b-DMAD)(dmpm)21 (31, either [Rh2(CO)3(dmpm)21 or [Rh2(CO)2(p-HFB)(dmpm)2] (4), prepared as described above The spectral data for 1 compare closely to that of the and allowed to stir under an atmosphere of dinitrogen for several dppm analogues [MM'(CO)B(dppm)z](M, M' = Rh, Ir; M hours. Subsequent characterization of the products was carried = Rh, M' = and in particular the carbonyl out by 31P(1HJNMR on the reaction mixture or by slP(lH}NMR stretches for 1 (1953,1912, and 1824 cm-l) are very close and infrared spectroscopic methods on THF or CHzClzsolutions to those for the above species. On this basis, 1 is assigned (or their deuterated counterparts) of the residue. the structure, diagram below, that is as observed for the The reaction of [Rh2(C0)2(p-HFB)(dmpm)2] (4) with acetyl Rh,, RhIr, and RhCo dppm analogues. In this formulation chloride entailed the addition of 2 equiv of the reagent (7.5 pL) the metals have been assigned a mixed-valence formulation to a purple toluene solution (8 mL) of 4 (0.052 mmol based on in which a pseudotetrahedral M'( 1-1 center forms a dative 80% conversion of [Rh2C12(CO)2(p-HFB)(dmpm)z]; 50 mg, 0.065 mmol). The solution color changed to orange-yellow within 15 bond to the M(1+) center, giving the latter a square-planar min. Stirring was continued for an additional 15 min; the solvent geometry. was then removed under vacuum, the residue was washed with The NMR data for 1 indicate that it, like the dppm hexane (20 mL), and the products were dried under dinitrogen. analogues, is fluxional at ambient temperature. At 22 "C The spectroscopic characterization of the products was carried the 31P(1HJNMR spectrum (Figure 1)is somewhat broad out in THF or THF-d8.
Results and Discussion (a) Reduction Reactions. The reduction of tram[RhCl(CO)(dmpm)], is carried out under an atmosphere of CO using a 1M solution of NaOH/H20 to yield [Rhz(CO)3(dmpm)z](I), which is isolated in reasonable yield (65%) as an air-sensitive orange-brown residue. This species is highly reactive and must be kept out of contact with chlorinated solvents to prevent re-formation of the starting material, trans-[RhC1(CO)(dmpm)I2. This chloro species is also obtained upon reaction of 1 with other chloro-containing reagents such as acetyl chloride, although HC1 and SOClz react with 1 to yield the tetrachloride [RhClz(CO)(dmpm)lz. Both chloride-containingproducts were identified by comparison of their spectra with those of the previously characterized specie8.l' Complex 1 can also be prepared from the reaction of sodium naphthalenide or sodium borohydride with trans- [RhCl(CO)(dmpm)12under a CO atmosphere. However, due to impurities which are also formed in the latter two methods, the preparation from NaOH/H20 represents the most reliable procedure. The reaction with NaOH/H20 presumably involves the formation of an intermediate species (18) Geary, W . J. Coord. Chem. Rev. 1971, 7, 81.
but nevertheless is typical of an AA'A"A"XX' spin system in which all four phosphorus nuclei are chemically equivalent. At -75 OC the 31P(1H}NMR spectrum is typical of an AA'BB'XY spin system, having two chemically inequivalent phosphorus environments. This suggests an equilibrium of the two metal centers via carbonyl transfer from one metal to the other, in which a simultaneous "merry-go-round" migration of the carbonyls around the Rh, framework also occurs. _..
c P -
1
The observation of only one carbonyl resonance at 22 "C (6 198.7) indicates that all carbonyls are exchanging at this (19) Deraniyagala, S. P.; Grundy, K. R. Inorg. Chem. 1985, 24, 50. (20) Sutherland, B. R.; Cowie, M. Organometallics 1986,4, 1637. (21) (a) Kubiak, C. P.; Eisenberg, R. J. Am. Chem. SOC.1980, 102, 3637. (b) Kubiak, C. P.; Woodcock, C.; Eieenberg, R. Inorg. Chem. 1982, 21,2119. (c) Woodcock,C.; Eisenberg, R. Inorg. Chem. 1985,24,1286. (22) Antonelli, D. M.; Cowie, M. Organometallics 1990, 9, 1818. (23) Elliot, D. J.; Ferguson, G.; Holah,D. G.; Hughes, A. N.; Jenninp,
M. C.; Magnuson, V. R.; Potter, D.; Puddephatt, R. J. Organometallics 1990, 9, 1336.
2770 Organometallics, Vol. 11, No. 8, 1992
Jenkins and Cowie
Table I. Infrared Spectroscopic Data for tlle Compounds4~* no. 1 2 3
4 5 6 7
8 9
compd [Rhz(CO)3(dm~m)zl [Rh(CO)(r-CO)(dmpm)Iz
V(C0) 1960 (m), 1925 (s), 1847 (m); 1953 (vs), 1912 (s), 1824 (m)' 1962 (m),1926 (m), 1914 (m, sh), 1847 (m) [Rh,(C0),(r-DMAD)(dm~m)~l 1956 (s), 1935 (m), 1685 (mid [Rhz(CO),(p-HFB)(dmpm)zl 1963 (s), 1942 (m) [Rh2(CO),OI-H)(dmpm)21[BF41 1980 (m,sh), 1960 (vs), 1895 (w) [Rh,(CO),(p-H)(dmpm)~lPF4I 1985 (e), 1958 ( 8 ) [Rhz(Co)z(pc-H)(r-DMAD)(dmpmhl W41 1988 (s), 1974 (m), 1743 (m)d [Rh,(CO),(F3CC=C(H)CF,)(dm~m)21[BFII 1995 (m),1973 (m), 1964 (m),1943 (w) [Rhz(CO),(F3CC=C(H)CF3)(p-CO)(dmpm),][BF41 2043 (m), 2020 (4,1993(m, br), 1792 (w,br); 2044 (vs), 2014 (vs), 1988 (vs), 1765 (vsp
others
1608 (w)o 1600 ( m P
"Abbreviations u s e d vs, very strong; s, strong; m, medium; w, weak; sh, shoulder. All values in cm-'. b T H F solution unless otherwise noted. Nujol. v(C0) of C02Me. e v(CC).
Table 11. NMR Spectroscopic Data for the CompoundsaFb VH)
compd
6(19F)
others
-CHz-
2
3
-7.17 (144 Hz)
4
-9.30 (142 Hz)
197.54 (dm, 'Jm4 = 58.4 Hz)
6
6.49 (98 Hz)
6
1.19 (83.2 Hz), 1.93 (81.5 Hz)'
194.1 ( 8 ) ; 188.3 (m)! 196.4 (Q, 'J= 34.1 Hz, 'Jp4 7.4 Hz)' 199.4 (dm, J = 67 Hz)'
1.78 (8, 24 H)'
3.32 (m, 4 H)'
7
-4.2 (104 Hz)
3.1 (m, 4 H )
8
-0.5 (m), -1.0 (my
196.14 (d, lJW
