Inorg. Chem. 1985, 24, 397-401
397
( b ~ y ) ~ ] ( p F , )94070-05-0; ~, [(NH3)5Ru11(bpa)Ru1'Cl(bpy)2](PF6)3,[(dpte)2Ru11C1(4,4'-bpy)](PF,), 94070-19-6; [(dpte)2CIRu11(bpe)](PF6), 94070-21-0; [(dpte)2CIRu"(bpa)](PF6), 94070-23-2; [(NH3)5Ru1194070-06- 1; [(NH3)5Ru111(bpa)Ru11Cl(bpy)2] (PF6)4. 94070-08-3; (bpe)](PF,),, 94070-24-3; [ ( N H , ) , R u " ( ~ ~ ~ ) ] ( P F , )54713-94-9; ~, [(dpte)2C1Ru1'(4,4'-bpy)Ru"CL(bpy)2](PF6)2, 94070-09-4; t r ~ n s - [ ( d p t e ) ~ R u ~ ~ 32648-33-2; Cl~], [(dpte)2CIRu"(NCCH3)](PF6), [ (dpte)2C1Ru11(4,4'-bpy)Ru"'Cl(bpy)2](PF6)3, 94070-1 1-8; 94070-26-5; dpte, 622-20-8; p-CH3+NCSH,CONH2,45791-94-4. [(dpte)2Ru"Cl(bpe)Ru"Cl(bpy)2](PF6)2, 94132-58-8; [(dpte)2C1Rurl(bpe)Ru"'Cl(bpy),] (PF6)3, 94070- 13-0; [(dpte)2CIRu11(bpa)Ru"CISupplementaryMaterial Available: Tables of elemental analysis data ( b ~ y )(PF6)2, ~] 94070- 14-1; [(dpte)2C1Ru11(bpa)Ru111Cl(bpy)2] (PF6)3, and UV-visible absorption maxima and extinction coefficients for the 497 34-3 6- 3; 94070-1 6 - 3; [ (bpy) 2RU1'CI(4,4'-bpy)] (PF,), compounds used in the study (6 pages). Ordering information is given [(bpy),Ru"Cl(bpe)] (PF6), 49734-42-1; [(bpy),Ru"Cl(bpa)] (PF,), 54713-80-3; [(NH1)sRu1'(4,4'-bpy)](PF6)2, 94070-17-4; on any current masthead page.
Contribution from the William Rand Kenan, Jr. Laboratories of Chemistry, The University of North Carolina a t Chapel Hill, Chapel Hill, North Carolina 27514
Fast Atom Bombardment and Field Desorption Mass Spectrometry of Organometallic Derivatives of Ruthenium(I1) and Osmium(I1) R O N A L D L. CERNY, B. PATRICK SULLIVAN, MAURICE M. BURSEY,* and T H O M A S J. MEYER
Received November 2, 1983 The fast atom bombardment (FAB) and field desorption (FD) mass spectrometric analysis of 18 involatile, cationic organometallic derivatives of 2,2'-bipyridine (bpy) complexes of Ru(I1) and Os(I1) containing s2-alkene, s2-alkyne,carbonyl, alkyl, and hydrido ligands is presented. Field desorption (FD) and fast atom bombardment (FAB) mass spectrometry are used in concert. In the area of (polypyridy1)metalcomplex chemistry, these techniques are powerful structural tools; the former gives information on the intact cation, and the latter, fragmentations characteristic of the ligands. The fragmentations can be interpreted on a chemical basis by invoking four concepts: redox fragmentation of metal-ligand bonds, i.e., homolytic dissociation; the simple loss of neutral ligands, depending upon their thermal lability; intramolecular, oxidative addition of coordinated bpy; reductive elimination of HX (X = C1, H, alkyl).
Introduction T h e use of new mass spectrometric techniques as tools for the characterization of organometallic complexes of low volatility has developed rapidly during the last several years. Specifically, field desorption (FD)mass spectrometryI4 has been applied in a variety of studies to yield parent ion molecular weight data, although in most instances very little fragment ion information is obtained. Fast atom bombardment (FAB) mass s p e c t r ~ m e t r y ,although ~,~ only applied in a few cases, promises to be extremely valuable: parent ion and fragmentation data are exhibited for most sample~.'-'~ One of the challenges to be met in utilizing FAB is t o relate the fragmentation patterns produced to the structures of the unknown organometallic complex, Le., to identify the major fragmentation pathways. Given our recent success in applying FAB to a series of coordination complexes and in interpreting the fragment ions in terms of t h e complexes' thermal chemistry, an obvious extension is t o organometallic complexes. In this paper we present primarily FAB spectral studies but, where appropriate, give complementary FD data, for a series of 2,2'-bipyridine (bpy) organometallic derivatives of Os(I1) and Ru(I1). T h e organometallic moieties in our studies are q*-alkene, $-alkyne, $-benzene, ~$cyclopentadienyl, carbonyl, alkyl, and hydride ligands. Beckey, H. D. Int. J . Mass Spectrom. Ion Phys. 1969, 2, 500-503. Games, D. E.; Gower, J. L.; Gower, M.; Kane-Maguire, L. A. P. J . Organomet. Chem. 1980, 193, 229-234. Games, D. E.; Gower, J. L.; Kane-Maguire, L. A. J . Chem. Soc., Dalton Trans. 1981, 1994-1996. McEwen, C. N.; Ittel, S . D. Org. Mass Spectrom. 1980, 15, 35-37. Barber, M.;Bordoli, R. S.; Sedgwick, R. D.; Tyler, A. N. J . Chem. Soc., Chem. Commun. 1981, 345-327. Barber, M.; Bordoli, R. S.; Sedgwick, R. D.; Tyler, A. N. Nature (London) 1981, 293, 270-275. Tkatchenko, I.; Neibecker, D.; Fraisse, D.; Gomez, F.; Barofsky, D. F. Int. J . Mass Spectrom. Ion Phys. 1983, 46, 499-502. Johnstone, R. A. W.; Lewis, I. A. S. Int. J . Mass Spectrom. Ion Phys. 1983, 46, 451-454. Barber, M.; Bordoli, R. S.; Sedgwick, R. D.; Tyler, A. N. Biomed. Mass Spectrom. 1981, 18, 491-49s. Miller, J. M. J . Organomet. Chem. 1983, 249, 299-302.
0020-1669/85/1324-0397$01.50/0
The results presented here are extremely encouraging with regard to the use of these spectroscopies in a complementary fashion for characterization of the molecular weight (parent ion mass) of unknown involatile organometallic species, especially cations. Generally, when FAB was unable to provide parent ion information, FD was able to do so. In addition, we will demonstrate t h a t t h e FAB fragmentation patterns can be interpreted by a combination of simple bond-cleavage processes and redox events.
Experimental Section Instrumentation. Field Desorption. A Du Pont 21-492B mass spectrometer modified for field desorption was used in this study. The instrument was operated at a 3-kV accelerating potential, and the cathode was held at -7 kV. Samples were dissolved in methylene chloride and placed on the emitter dendrites by the dipping method. Cobalt dendrites were used; their preparations have been described elsewhere." Heating currents of 15-30 mA were sufficient to desorb the samples The source was maintained at ambient temperature. Fast Atom Bombardment. A VG 7070 mass spectrometer equipped with a standard VG data system was used in the FAB experiments. The instrument was fitted with a modified saddle field ion source obtained from Ion Tech Ltd. to serve as the atom beam gun. Xenon was used to produce the primary beam. A primary current of 1 mA at an energy of 4-8 KeV provided good sample ion intensities. A stainless-steel probe tip was covered with a small piece of aluminum foil to provide a clean surface for each sample. The sampie was placed onto the foil as either a solution or suspension in glycerol. In cases where low solubility in this glycerol matrix seemed to result in poor spectral quality, the sample was first dissolved in a small amount of dimethylformamide. This solution was then placed on the probe with a small amount of glycerol. This enabled us to obtain spectra of previously intractable complexes. Samples. The carbonyl complexes [Ru(bpy),(CO)X] (PF,) (X = H, CI) and [Os(bpy),(CO)X](PF,) (X = H, CI, CF,, CF3C02)were prepared by published techniques.12 The synthesis of the complex Ru($-C5Hs)(bpy)Cl will be described in a forthcoming publication." The (1 1) Bursey, M. M.; Rechsteiner, C. E., Jr.; Youngless, T. L.; Fraley, D. F.; Sammons, M. C.; Haw, J. R. Adv. Mass Spectrom. 1978, 7,932-938. (12) (a) Caspar, J. V.; Sullivan, B. P.; Meyer, T. J. Organometallics 1983, 2, 551-554. (b) Sullivan, B. P.; Caspar, J. V.; Johnson, S . R.; Meyer, T. J. Ibid. 1984, 3, 1241.
0 1985 American Chemical Society
398 Inorganic Chemistry, Vol. 24, No. 3, 1985
Cerny et al.
Table I. Major Ions Observed in the E'AB Spectra of Hydrocarbon-Ligand (L) ,Complexes of Ru(I1) and Os(I1) m/z (re1 intens)" (M - Cl)* (M - L - HCl)* other peaks M + C (M L)' cation ... 503 (100) 567 (1 3) 539 (164) [os(bpY), (v~-CH,=CH,)C~]' ... 503 (100) 382 (100ld 693 (15) 539 (123) [0~(bpy),(q~-PhCH=CH,)Cl]+ 621 (96) 539 (182) ... 503 (100) [O~(bpy),(q*-CH,CH,C~CH,CH,)Cl]+ ... 503 (100) 473 (50)P ... 539 (192) [OS(bpy),(q'-PhC
