547
Inorg. Chem. 1993,32, 547-553
Oxidative Addition of Methyl Iodide to Monosubstituted and Disubstituted Derivatives of Osmium PentacarbonyI Gianfranco Bellachioma, Giuseppe Cardaci,' Alceo Macchioni, and Pierfrancesco Zanazzi Dipartimento di Chimica and Dipartimento di Scienze della Terra, sez. Cristallografia, Universitii di Perugia, 1-06100Perugia, Italy
Received January 29, 1992 Oxidative addition at room temperatureof CH31to Os(CO)4L or Os(CO)3L2 (L= PMe3)gives complexes [Os(CO),LCH3]I ( 3 ) or [OS(CO)~L~CH~]I (5), respectively. Complexes 3 and 5 react at higher temperature (50-70 "C) to give complexes Os(CO)3LCH3I (7) and OS(CO)ZL~CH~I (9), respectively. If this reaction is carried out in chloride-containingsolvents,the formation of Os(CO)3L(CH3)CI (8) and OS(CO)ZL~(CH~)CI (10) is also observed. Chloride abstraction from solvent during the reaction suggests a radical mechanism for the oxidative addition reaction. During the purification of complexes 9 and 10 by HPLC with acetonitrile (CH3CN) as eluent, complex [OS(CO)~L(CH~CN)CH~]I was obtained; it was transformed by reaction with NaBPh4 to the complex [OS(CO)~L(CH~CN)CHJ]BP~~ (14). The structures of complexes 14 and 9 have been solved by single-crystal X-ray diffraction methods. Com lex 14 crystallizes in the monoclinic space group ??&/a with lattice parameters u = 20.877 (3) A, b = 19.935(3) c = 8.887 (3) A, and /3 = 98.92 (2)O ;it contains 4 molecules/cell. The structure has been solved by using 2729 observed reflections and refined to R , = 0.059. Complex 9 crystallizes in the monoclinic space group P21/u with lattice parameters u = 13.979 (3) A,b = 9.124 (2)A, c = 13.950 (3) A,and fl = 107.70 (2)O; it contains 4 molecules/cell. The structure has been solved by using 1617 observed reflections and refined to R , = 0.043.
1,
Introduction
c35
Many complexes of the type M(CO)zLzRXIJ(M = Fe, Ru; X = halides; L = phosphine ligands) have been prepared via oxidative addition of alkyl halides to disubstituted complexes] of iron and ruthenium or by other methods.2 Oxidative addition of alkyl halides was observed in only one case with the monosubstituted M(C0)4L complexe~.~ Extensive studies on the reactivity of thesecomplexeshave been carried out, with particular reference to the stereochemistry of CO1cJb,Hand isocyanide7J insertion. R20s(C0)4 and RHOs(C0)4 are described in literature and were prepared by oxidative addition of Me1 to the HOS(CO)~a n i ~ n . ~OsRX(C0)4 J~ complexes were also obtained by electrophilic cleavage with X2 (X = C1, Br, I) of RzOs(CO)4,11via radical reaction1* or via migratory in~erti0n.l~Substituted derivatives with phosphine ligands cannot be obtained by direct To whom correspondence should be addressed at the Dipartimento di Chimica. (1) (a) Pankowski, M.; Bigorgne, M. J . Orgunomer. Chem. 1971,30,227234. (b) Reichenbach, G.; Cardaci, G.; Bellachioma, G. J. Chem. Soc., Dulron Truns. 1982,847-850. (c) Jablonski, C. R. Inorg. Chem. 1981, 20, 3940-3947. (d) Cardaci, G.; Bellachioma, G.; Zanazzi, P. F. Organomerullics 1988, 7, 172-180. (e) Cardaci, G.; Reichenbach, G.; Bellachioma, G.; Wassink, B.; Baird, M. C. Organomerullics 1988, 7, 2475-2479. (2) (a) Barnard, C. F.J.; Daniels, J. A.; Mawby, R. J. J . Chem. Soc., Dulron Trans. 1976, 961-966. (b) Barnard, C. F. J.; Daniels, J. A.; Mawby, R. J. J. Chem. SOC.,Dulron Trans. 1979, 1331-1338. (3) Cardaci, G. J. Orgunomer. Chem. 1987, 323, C10412. (4) Cardaci, G.;Reichenbach, G.; Bellachioma, G. Inorg. Chem. 1984,23, 2936-2940. ( 5 ) Wright, S.C.; Baird, M. C. J. Am. Chem. Soc. 1985, 107,68994902. (6) Pankowski, M.; Bigorgne, M. J . Organomer. Chem. 1983, 251, 333338. (7) McCooey, K. M.; Probitts, E. J.; Mawby, R. J. J . Chem. Soc., Dulron Truns. 1987, 1713-1716. (8) (a) Cardaci, G.; Bellachioma, G.; Zanazzi, P. F. Polyhedron 1983,967968. (b) Bellachioma, G.;Cardaci, G.; Zanazzi, P. F. Inorg. Chem. 1987, 26, 8k91. (c) Bellachioma, G.; Cardaci, G.; Macchioni, A.; Reichenbach, G. Gurr. Chim. Irol. 1991, 121, 101-106. (9) L'Eplattenier, F.;Pelichet, C. Helo. Chim. Acra 1970,53, 1091-1099. (10) L'Eplattenier, F. Inorg. Chem. 1969, 8, 965-970. (11) Kelland, J. W.;Norton, J. R.J.Orgunomer. Chem. 1978,149,185-194.
c34
C29
u01 Figure 1. Molecular structure of the cation of complex 14.
substitution with L because of reductive e1iminati0n.I~Rather, general oxidative addition methodsi3~f5J6 must be used. In this work we describe the preparation and the structural characterization of alkyl complexes of osmium obtained by oxidative addition of CH31to monosubstituted and disubstituted derivatives of osmium pentacarbonyl. (12) Carter, W. J.; Kelland, J. W.; Okrosinski, S.J.; Warner, K. E.; Norton, J. R. Inorg. Chem. 1982, 21, 3955-3960. (13) Grundy, K.R.; Roper, W. R. J. Orgonomet. Chem. 1981,216,255-263. (14) Norton, J. R. Acc. Chem. Res. 1979, 12, 139-145. (15) Headford, C. E. L.;Roper, W. R. J. Orgunomer. Chem. 1980, 198, C7-CIO; 1983, 244, C53-C56. (16) Clark, G.R.; Edmonds, N. R.; Pauptit, R. A.; Roper, W. R.; Waters, J. M.; Wright, A. H. J. Organomer. Chem. 1983, 244, C57460.
0020-166919311332-0547$04.00/0 Q 1993 American Chemical Society
548 Inorganic Chemistry, Vol. 32, No. 5, 1993
C6
Figure 2. Molecular structure of complex 9.
Experimental Section Thesolvents (benzene,toluene, CH2C12,etc.)weredried by conventional methodsI7 and deaerated by bubbling with nitrogen. Tetrahydrofuran (THF) was purified as described in ref 18 and freshly distilled before use. Acetonitrile (ACN) and CH,I were purified as described in refs 19 and 20, respectively. Trimethylphosphine was prepared following the method described by Schmidbaur.21 The other phosphine ligands were commercially obtained. The IR spectra were obtained with a 1725X FTIR Perkin-Elmer spectrophotometer or with a 983 Perkin-Elmer conventional spectrophotometer. The IH, I3C, and ,IP(H) NMR spectra were recorded on a Bruker AC 200 spectrometer. The IH and I3C NMR chemical shifts are relative to tetramethylsilane as internal reference, and the 3iP(H) NMR chemical shifts are relative to 85% H3P04in D20 with a positive sign indicating a shift to lower field. The elemental analyses were carried out with a Carlo Erba 1106 elemental analyzer. The structures of the complexes are given in Figures 1 and 2; their IR and NMR characterization is given in Table I. Preparation of [Os(CO)4PMe3] (1) and [Os(C0)3(PMe3)~](2). 0%( C 0 ) 1 2(1 g) was dissolved in 70 mL of toluene, and the solution was reacted with a solution (30 mL) of PMe, in ethyl ether (molar ratio 5/1) in a Carius tube at 98 OC for 10 days. At the end of the reaction, the formation of [Os(CO)4PMe,], [Os(CO),(PMe,)2], and [OS3(c0)9(PMej),] was observed by the CO stretching bands. The solvent was removed under reduced pressure, and the solid residue was sublimed at P ~ i10-2 : mmHg. The complex [Os(CO)4PMe,] (0.65 g) was obtained at 40 OC. The complex [Os(CO)j(PMe3)2] (0.85 g) was obtained at 70 OC. The trisubstitutedcluster [Os,(C0)9(PMe&] remainedin the residue and was identified by its CO stretching bands22(YCO = 2020, 1866 cm-I in n-hexane). [Os(C0)4PMe,] wascharacterized by analysis as C7H9040sP. Anal. Found: C, 22.4; H, 2.35. Calcd: C, 22.22; H, 2.40. [Os(CO)~(PMe3)~] was characterized by analysis as C9H18030sP2. Anal. Found: C, 25.7; H, 4.40. Calcd: C, 25.30; H, 4.25. The same reaction was also carried out with PMeZPh. In this case, the reaction was carried out at 65 OC using the ligand PMe2Ph as solvent and O S ~ ( C O (0.15 ) ~ ~ g). After 4 days the reaction was complete. The formation of [ O S ( C O ) ~ P M ~ (~Y CPO~=] 2059, 1876, and 1833 cm-I, in CH2CI2) and [Os(CO)j(PMe2Ph)2] ( Y C O = 1879 cm-I, in CH2CI2) was observed. Preparation of [Os(CO)~PMe3(CH~)]I(3) and [Os(CO)dPMen(CH3)JBPh (4). [Os(C0)4PMeJ (0.3 g) was added to CH,I ( 5 mL), and the solution was cooled to -20 "C and stirred in a reactor under nitrogen. After 1 h the temperature was increased to +5 "C. The (17) Weissberger, A.; Proskauer, E. S. Technique o/ Organic Chemistry: organic Soluenrs, 2nd ed.; Interscience: New York, 1955; Vol. VII. (18) Keblis, K. A.; Filbey, A. K. J . Am. Chem. Soc. 1960,82, 4204-4206. (19) Coetzee, J. F.; Cunnigham, G . P.; McGuire, D. K.; Padmanabham, G . R. Anal. Chem. 1962, 34, 1139-1143. (20) Douek, I . C.; Wilkinson, G . J . Chem. Soc. A 1969, 2604-2610. (21) Wolfsberger. W.;Schmidbaur,H.Synth.Reacr. fnorg. Mer. Org. Chem. 1974, 4, 149-1 56. (22) Tripathi, S.C.; Srivastava, S.C.; Mani, R. P.; Shrimal, A. K. tnorg. Chim. Acta 1975, 15, 249-290.
Bellachioma et al. formationof a white precipitate was observed. The reaction wascomplete after 2 days. The precipitate was filtered out and washed with CH3I (yield 70%). The solid 3 was analyzed as C ~ H I ~ I O I P OAnal. S. Found: C, 18.60; H, 2.25. Calcd: C, 18.47; H, 2.32. The solid 3 was dissolved in CHjOH and precipitated with NaBPh4. Complex 4 was filtered out and analyzed as C32H32B04POs. Anal. Found: C, 54.2; H, 4.50. Calcd: C, 53.94; H, 4.53. Preparation of [ O ~ ( C O ) ~ ( P M ~ ~ ) Z ( C(5) H and ~ ) J[Os(C0)3(PMe3)~(CH3)IBPh (6). [Os(CO),(PMe3)2] (2) (1 g) was added to CHjI (IO mL), and the mixture was cooled to-30 OC and stirred in a reactor under nitrogen. The formation of a white precipitate 5 was immediately observed. The solution was filtered. The CH3I solution showed a series of bands in the following range of CO stretching: YCO = 2026, 2015, 2005,1985, 1957, 1945, and 1935 cm-I. Also the IH and 31P(H]NMR spectra in CD2C12 of the solid, obtained by removing CH31, showed a seriesofbandsdifficult toassign. Inparti~ularthe~~P(H]NMR spectrum indicates the presence of about IO different chemical species. Thewhitesolid5(0.82g,yield62%)wasanalyzed asCloH21IOjP2Os. Anal. Found: C, 21.3; H, 3.92. Calcd: C, 21.13; H, 3.72. Complex 5 was dissolved in CHjOH and precipitated with NaBPh4. A white solid 6 (yield 90%) was obtained. Complex 6 was analyzed as C , ~ H ~ I B O ~ P ~ Os. Anal. Found: C, 53.3; H, 5.52. Calcd: C, 53.69; H, 5.43. Reaction of Complex 5 in Chloride Solvents. The reaction was carried out in CH2C12 and 1,2-dichlorocthane. The results were identical in the twosolvents;the reaction was much slower in CHzC12 since the temperature could not be raised higher than 40 "C. Now we describe the reaction in 1,2-dichloroethane. Complex 5 (1.9 g) was dissolved in 1,2-dichloroethane (50 mL), and thesolution wasdeaeratedand heated to65 OC. Thereaction wascomplete after 8 h. The reaction product remained stable for 3 days. Solvent was removed by evaporation under reduced pressure with an oil pump (P= mmHg). The solid residue was dissolved in n-hexane. The IR spectrum shows two CO stretching bands; accurate analyses of the IR form of the bands indicate the presence of other bands. This conclusion was confirmed by the IH NMR spectrum in CD2C12, which showed two Os-CH, triplets and two PMe3 triplets, indicating the presence of two complexes. Attempts to separate the two complexes by fractional crystallization were unsuccessful. A separation was obtained by HPLC, using an apolar C18 preparative column (Dynamax-60A) and CH,CN/ H20 (90/10) as the eluent at room temperature. Four major and other less important fractions were obtained. After elution, solvent was evaporated fromeach and theremainingsolid extracted with diethyl ether and dried with dehydrated MgS04. The solution was filtered and the solvent removed by evaporation under reduced pressure. Two of the fractions contained the two above mentioned complexes. They were purified by crystallization and obtained as light white needles. Oneofthem wasanaIyzedasC9H21102P20~(9).Anal. Found: C, 19.9; H, 3.95; I, 23.3; P, 11.3. Calcd: C, 20.01; H, 3.92; I, 23.49; P, 11.47. Molecular weight: found (osmometric method in benzene), 535 f IO; calcd, 540.34. The other analyzed as C ~ H Z I C I O ~ P (10). ~ O S Anal. Found: C, 23.8; H, 4.99; CI, 8.1; P, 13.6. Calcd: C, 24.08; H, 4.72; CI, 7.90; P, 13.80. Molecular weight: found (osmometric method in benzene), 440 f IO; calcd, 448.88. The two remaining fractions contained two new complexes, insoluble in apolar solvents. One of these gives the following IR bands: YCO = 2028 and 1960 cm-I in CH2C12. The IH NMR spectrum in CD2Cl2 shows I C H ~= 4 . 1 4 (t) (,JHP 8.4 Hz) and ~ P M =~ ,1.73 (m) ( I 2 J ~ + p 4 J ~ p= l 4.0 Hz); the 'lP(H) NMR spectrum in CD2C12 shows a singlet at I = -37.9 ppm. The other complex gives the following IR bands: YCO = 2029 and 1963 cm-I in CH2C12. The ' H NMR spectrum in CD2C12 , (m) (IVHP + shows I C H ~= -0.13 (t) OJHP= 8.5 Hz) and ~ P M =~ 1.75 4J~pl= 4.1 Hz); the ,lP{H) NMR spectrum in CD2C12 shows a singlet at I = -37.9 ppm. These two complexes appear very similar. Both these were dissolved in CH3OH and precipitated with NaBPh4. An identical white solid complex was obtained (14), which analyzed as C3sM44BN02P20s. Anal. Found: C, 54.6; H, 5.55; N, 1.75. Calcd: C,54.33;H, 5.73;N, 1.81. Thespectroscopiccharacterizationofcomplex 14 is given in Table I. On the basis of this behavior compared to that of the previous insoluble complexes in apolar solvent, these compounds were attributed as having the same structure as that of 14. exccpt with and the anions CI- and I-: [OS(CO)~(PM~~)~(CH~CN)CHI]CI [OS(CO)~(PM~J)~(CH,CN)CH,]I, respectively. The less important fractions, analyzed by IR and NMR (see Table
Oxidative Addition of CHJ to Os(CO),L, Complexes
Inorganic Chemistry, Vol. 32, No. 5. I993
549
Table 1. IR and IH, 31P,and I3C NMR Spectral Data for the Complexes NMR:' 6,ppm, and J , Hz complex
IR: vc0,cm-l 2061,1981, 1939
'H
-"P{'H)
"C
36
1886 2 158 s, 2098 s, 207 1 vs
= -49.2 S, J p - a 147, 6co 189.8, ~ C H = , 22.0 d, JP-M =~ 38.9, 2Jp
