Organometallics 1983, 2, 187-189
thylidyne carbon (6 8.6) and a resonance for the carbonyl carbon (6 160.3) in the same region as for the carbonyls bound to osmium. In the absence of specific isotopic labeling we are unable to attribute one of the IR bands observed in the v(C0) region to the CCO ligand.8 Protonation of H20s3(CO),(CCO) leads to H30s3(CO),(CCO)+, as indicated by bleaching of the color from yellow to white and by 'H NMR and IR data., It is probable that both H30s3(CO),(CCO)+and the analogous tricobalt cation CO~(CO)~(CCO)+ studied by Seyferth and co-workers1° have the CCO ligand in an upright position as well. This contrasts with the evidence that both H,OS~(CO)~(C=CH~)+'' and CO~(CO),(C=CHR)+'~ have tilted configurations. A molecular orbital analysid3 of the preference for a tilted configuration in Co3(CO),(CCH2)+ attributed it to the empty orbital on the P-carbon interacting differentially with the high-lying, filled e set of metal ring orbitals. This leads to an energy decrease with bending. On the other hand, since the CCO ligand has its p-r* orbitals in e pairs, there appears to be no incentive for it to tilt away from the perpendicular position in Co3(C0),(CCO)+or H30s3(C0),(CCO)+. It is significant, however, that even when the symmetry of the metal framework is reduced to C, in HZOs3(CO),(CCO),an upright orientation is preferred. The crystal structure of H O S ~ ( C O ) ~ ~ ( C shows H ) ~ that the bridging methylidyne ligand comes into close contact with an axial carbonyl of the Os(CO), unit. This feature suggests that the facile thermal rearrangement of HOs3(CO),,(CH) into H20s3(CO),(CCO) proceeds via an intermediate in which the methylidyne and carbonyl ligands have coupled into a "ketenyl" HC=C=O ligand. Analogous compounds HM3(CO)g(RC=C=CHz) (M = Ru, Os) with isoelectronic "allenyl" ligands are known,14 and the coupling of methylidyne and carbonyl ligands on tungsten (mediated by AlCl,) has been observed re~ent1y.l~Related ligands formed from aryl-substituted methylidyne compounds also are known.I6 H20s3(CO),(CCO) reacts slowly with Hz (1atm) in refluxing heptane or toluene to provide H,OS~(CO)~(CH)'~ as the sole product observed spectroscopically (IR and 'H NMR) and isolated after TLC in 54% yield. Under similar conditions with a mixture of H2 and CO (3:1), no reaction is observed. The observed product implies the generation of HOs,(CO),CH, which in turn suggests that the methylidyne-carbonyl coupling that leads to Hz0s3(CO)g(CCO) is reversible.18 Further reactions of Hz0s3(C0)9(CCO)and (8)The weak band at 1644 cm-' observed previously' for a Nujol mull of H0Os.JCO)dCCO) is not observed for a Nuiol mull ureuared in an inert$td;kah& box. Thus. this band is Drobabiv due to; small amount ifH20s3(Cb)g(CC02H)formed in makiig the mull. (9)For [H30s3(C0)9(CCO)]BF4:'H NMR (CH,Cl,, 35 "C) 6 -19.36 (s); IR (v(CO), Nujol) 2155 (m), 2125 (s), 2069 (s, br), 2039 ( 8 , br) cm-'. (10)(a) Seyferth, D.; Hallgren, J. E.; Eschbach, C. S. J. A m . Chem. SOC.1974.96.1730. (b) Sevferth.. D.: . Williams, G. H.: Nivert, C. L. Inore. Chem. 1977,'16,758: (11)Deeming, A. J.; Hasso, S.; Underhill, M.; Canty, A. J.; Johnson, B. F. G.; Jackson, W. G.; Lewis, J.; Matheson, T. W. J. Chem. Soc., Chem. Commun. 1974,807. (12)Edidin, R. T.;Norton, J. R.; Mislow, K. Organometallics 1982, 1, 561. (13)Schilling, B. E. R.; Hoffman, R. J. Am. Chem. SOC.1979,101, 3456. (14)(a) Deeming, A.J.; Hasso, S.; Underhill, M. J. Chem. Soc., Dalton Trans. 1975,1614. (b) Gervasio, G.;Osella, D.; Valle, M. Inorg. Chem. 1976,15, 1221. (15)Churchill, M.R.; Wasserman, H. J.; Holmes, S. J.; Schrock, R. R. Organometallics 1982,1 , 766. (16)Kreissl, F. R.; Uedelhoven, W.; Erber, K. Angew Chem., Int Ed. Engl. 1978,17,859.Also see: Martin-Gil, J.; Howard, J. A. K.; Navarro, R.; Stone, F. G. A. J . Chem. Soc., Chem. Commun. 1979,1168. Orama, 0.;Schubert, U.; Kreissel, F. R.; Fischer, E. 0. Z . Naturforsch., B: Anorg. Chem., Org. Chem. 1980,35B, 82. (17)Calvert, R. B.; Shapley, J. R. J. A m . Chem. SOC.1977,99,5225. I
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H30s3(C0),(CCO)+are being explored.
Acknowledgment. This research was supported at the University of Illinois by NSF Grant CHE 81-00140 (J.R.S.) and at S.U.N.Y.-Buffalo by NSF Grant CHE 80-23448 (M.R.C.). Registry No. 1, 83573-03-9;3, 83585-34-6. Supplementary Material Available: Tables of positional parameters, anisotropic thermal parameters, and observed and calculated structure factors (15 pages). Ordering information is given on any current masthead page. (18)An alternative possibility is that H20s3(CO)g(CCO) reacts with H, to form H30s3(CO)g(CCHO),which subsequently decarbonylates. This strikes us an unlikely, since Co3(CO)g(CCHO)is reduced by H, exclusively to C O ~ ( C O ) ~ ( C C H ~However, ).'~ we are currently attempting to prepare H30s3(CO)&CCHO)in order to check its behavior. (19)Seyferth, D.; Nestle, M. 0. J . Am. Chem. SOC.1981,103, 3320.
Reactive Charge-Transfer Complexes as Precursors for New Organometallic Salts. Synthesis and Structure of [(q5-C,H,),Fe],,,+[( NC),C=C( CN)O]Brlan W. Sullivan and Bruce M. Foxman" Department of Chemistry, Brandeis University Waltham, Massachusetts 02254 Received July 20, 1982
Summary: Reaction of the ferrocene-tetracyanoethylene charge-transfer complex in ethyl acetate gives the title complex in excellent yield. Crystals of the new material contain both ferrocene and ferricenium ions: ferrocene and tricyanoethenolate anion form a donor-acceptor stack in the crystal structure, while the ferricenium ions form a nearly linear stack.
In 1964 Rosenblum' demonstrated that the reaction of ferrocene with tetracyanoethylene (TCNE)2led to a 1:l charge-transfer complex of the neutral closed-shell components. In that same paper a singular discovery was also presented: the neutral complex decomposed either in solution or in the solid state to yield both the neutral congeners and black needles of the salt ferricenium pentacyanopropenide in low yield.3 Thus, the reaction proceeds with covalent bond formation to yield an organometallic salt which has not yet been synthesized by alternative means.4 These results suggested an as-yet-unrealized opportunity, viz., that reactive charge-transfer complexes might be employed as precursors for new and otherwise unavailable organometallic phases. With this goal in mind we felt that a reinvestigation of the reaction chemistry of the ferroceneTCNE charge-transfer complex was warranted. This communication reports the high-yield synthesis and structure of a previously unknown product,
[(~5-C5H5)~Fell,~'[(NC),C=C(CN)O-l. In a typical experiment, equimolar amounts of ferrocene (0.642 g, 3.44 mmol) and TCNE (0.442 g, 3.44 mmol) are dissolved in 15-20 mL of purified, warm (50 "C) ethyl (1)Rosenblum, M.; Fish, R. W.; Bennett, C. J . Am. Chem. SOC.1964, 86, 5166. (2)Webster, 0.W.; Mahler, W.; Benson, R. E. J. Am. Chem. SOC.1962, 84, 3678. (3)This reaction was later observed and reported by other workers: Brandon, R. L.; Osiecki,J. H.; Ottenberg, A. J.Org. Chem. 1966,31,1214. (4)Sullivan, B. W., unpublished observations. Structural characterization of the salt is underway.
0 1983 American Chemical Society
188 Organometallics, Vol. 2, No. I , 1983
Communications
Figure 1. A stereoview of the crystal structure of [(V~-C~H~)~F~!~,~+[(NC)~C=C(CN)O](50% probability ellipsoids). Only one of the two disordered orientations of the tricyanoethenolate anion is shown.
acetate. The initially light green solution is placed in a refrigerator and slowly turns quite dark as it is allowed to stand in air. After intervals of several days, the title complex is collected in the form of highly reflective black crystals (three harvests): 0.771 g (84% based on ferrocene); mp 137-138 "C; IR (KBr) 3112,2203,2180,1595 cm-'; y = 2.49 p ~ Anal. . Calcd for C40H30N602Fe3:c, 60.49; H, 3.81; N, 10.58. Found: C, 60.68; H, 4.12; N, 10.63. The analytical and spectroscopic data are consistent with the formulation [(C5H5)2Fe]l,5+[C5N30]-; since this is an unusual st~ichiometry,~ an X-ray structure determination was carried out. Crystals of the title complex are monoclinic of space group C2/m with a = 14.105 (3) A, b = 15.471 (3) A, c = 8.728 (2) A, p = 112.84 (2)", pobsd = 1.50 (1)g4-Xl-3,6and Pcalcd = 1.51 g . ~ m for - ~ 2 = 4. Full-matrix least-squares refinement of positional and thermal parameters for all atoms, using 1264 data for which F > 3.92a(F) and 28MoKa < 51", gave R = 0.036 and R, = 0.046. The crystal structure (Figure 1)is composed of one-dimensional segregated stacks of (a) ferricenium ions and (b) alternating 1:2:1 ...ferrocene-bis(tricyanoetheno1ate)-ferrocene ... stacks. The latter stack is probably best viewed as a weak 1:2 donor-acceptor complex between ferrocene and the tricyanoethenolate anion.' Formally, this material is to be considered a ternary phase of the type [D+][Do,5A-], where D and A are donor and acceptor molecules, respectively. The observed arrangement may by prototypical of this stoichiometry, although we know of no other examples. The details of the interactions within each stack are as follows. In the ferricenium ion stack, the Fe atoms lie on twofold axes a t (0, 0.231, 0) and (lI2,0.269, 0); thus, the 'I4, 0), cations are related by an inversion center at and form infinite, zigzag chains along a , with relative displacements in b from one another of 0.59 A. The intercation ring-bring distance is 3.61 A, very similar to the distance of 3.63 A reported for 1,l'-dimethylferricenium (TCNQ)2.s Individual cations are rigorously eclipsed and have an Fe-ring center distance of 1.700 (2) A, average Fe-C distance of 2.073 (2) A, and C5H5rings at an angle of 4.6". The 1:2 ferrocene-tricyanoethenolate ion (TCEA-) stack is comprised of disordered TCEA- ions occupying sites of (5) Herbstein, F. H. "Perspectives in Structural Chemistry"; Dunitz, J. D., Ibers, J. A., Eds.; Wiley: New York, 1971; Vol. 4, p 166. (6) Determined by neutral bouyancy in CeHs-CC1,. (7) In acetonitrile solution 0.1 M in tetrabutylammonium hexafluorophosphate, the TCEA anion exhibits a cathodic peak a t -1.56 V relative t o the Ag/AgCl electrode in saturated NaCl. (8) Wilson, S. R.; Corvan, P. J.; Seiders, R. P; Hodgson, D. J.; Brookhart, M.; Hatfield, W. E.; Miller, J. s.;Reis, A. H.; Rogan, P. K.; Gebert, E.; Epstein, A. J. "Molecular Metals";Hatfield, W. E., Ed.; Plenum Press: New York, 1979; p 407. TCNQ = 7,7,8,8-tetracyano-p-quinodimethane.
m I
Figure 2. Disorder (1:l) observed for the tricyanoethenolate
anion.
m symmetry and ordered ferrocene molecules of crystallographic 2 / m symmetry. Elemental analysis and IR spectra were crucial in establishing the presence of the enolate anion, owing to the complex nature of the disorder (the C=C bond of the TCEA- anion intersects the mirror plane at an angle of 40" (Figure 2), and a cyano N atom and the 0 atom trans to it lie on the mirror plane). However, in the final refinement, this disorder has been well resolved; the C=C (1.387 (9) A) and C-0 (1.246 (7) A) bond lengths indicate that both resonance forms of the anion are important. Unlike the structure of ferrocene, where it is likely that the disordered ferrocene molecules are nearly e c l i p ~ e d , ~ it Jwould ~ appear here that the ferrocene molecules are not disordered and are staggered. Although the ferrocene C5H5rings show considerable inplane libration, the location of H atoms strongly suggested a staggered configuration, and refinement proceeded successfully only for this model. Within the 1:2 stack the interplanar distance between centrosymmetrically related anions is 3.69 A, and the ferrocene-anion average separation is 3.47 A, which is longer than the revised interplanar distance,l0 3.28 A, in ferrocene-TCNE.ll However, the value of 3.47 A is misleading, in that the TCEA- anion plane is tipped 9.3" toward the C5H5rings of ferrocene about an axis perpendicular to the mirror plane. This serves to move the negatively charged 0 atom away from the C5H6ring plane (3.78 A) and the trans-CGN group very near to the plane (3.12 A). These phenomena are independent of the anion disorder and may account for the observed staggered ar~~~
~
(9) Seiler, P.; Dunitz, J. D. Acta Crystallogr.,Sect. E 1979, E35, 1068. Koetzle, T. F.; Takusagawa, F. Ibid. 1979, B35, 1074. (10) A recent redetermination of the structure of ferrocene-TCNE at room temperature in our laboratories shows that the ferrocene molecule is disordered in a similar manner to that found in ref 9. (11)Adman, E.; Rosenblum, M.; Sullivan, S.; Margulis, T. N. J.A m . Chem. SOC.1967, 89,4540.
Organometallics 1983, 2, 189-191
rangement. The ferrocene molecules have an Fe-ring center distance of 1.656 (4)A and an average F A ! distance of 2.018 (4)A. This material cannot be recrystallized nor can it be assembled from its congeners. These observations are consistent with the solid complex being a kinetically formed phase,12 likely a decomposition product of ferricenium-TCNE-. which has been shown to be in equilibrium with ferrocene-TCNE. If moisture (but not oxygen) is excluded from the reaction described above, the products include both TCEA- and pentacyanopropenide anions. This latter observation is in excellent agreement with the reactivity pattern observed, e.g., in acetonitrile solutions of the TCNE radical anion.13
Acknowledgment. This work was supported in part by the Office of Naval Research. We thank L. Acampora and G. D. Zoski for performing electrochemical measurements and D. J. Sandman, A. Reis, and L. S. Stuhl for helpful discussions. Registry No. [ (C5H,),Fe]l,5+[CSN,0]-,83587-82-0; ferrocenetetracyanoethylene, 12116-72-2.
Supplementary Material Available: Tables of atomic coordinates, thermal parameters, and observed and calculated structure factors (7 pages). Ordering information is given on any current masthead page.
189
tention on the chemistry of bi- and polynuclear carbonyl derivatives containing these m0ieties.l Several examples of attack by amines on coordinated CO in Ru&CO),~and O S ~ ( C O )have , ~ been described,2 and Kaesz3 has recently generated edge bridging p-O=C(X) groups from anionic nucleophiles (NMe2-, Me-, or OR-) via the proposed intermediacy of q’-C(=O)X species. Oxygen and carbon coordinated CO have also been implicated in the catalytic reduction of CO by binuclear ruthenium systems4 although the proposed intermediates were not isolated. Intuitively one might expect both ql- and p-O=C(X) complexes to be involved in homogeneously catalyzed or stoichiometric reductive carbonylations of organic substrates in the presence of polynuclear compounds. We wish to report the synthesis of the novel, a-substituted p-acyl complexes Mz(CO)6[p-O=CCH=CPhNRR’](PPh2) (2, M = Fe, Ru, R = Ph, R’ = H; M = Ru, R = R’ = Et, n-Pr, R, R’ = 2-EtC5H9)via the facile carbonylation-amination of the unsaturated alkynyl ligand in M,(CO),(~-T~-C=CP~)(PPh2). Our results have relevance to strategies for the elaboration of carbocationic multisite bound unsaturated ligands and to the synthesis of oxygenates from C0.4 Furthermore trapping of p-O=CCH=C(Ph)NRR’ ligands in 2 suggests the possible use of binuclear carbonyls in reductive carbonylations of the Reppe-type, reactions that are at present mechanistically o b ~ c u r e . ~
(12)Sandman, D. J. Mol. Cryst. Liq. Cryst. 1979,50, 235. (13)Webster, 0. W.; Mahler, W.; Benson, R. E. J . A m . Chem. SOC. 1962,84, 3678.
/x -M
Ao=
M
I Carbonylation and Amination of p-v2-Acetylides In M2(CO),( p-v2-C=CPh)( PPh,): Synthesis of p-O=CCHC( Ph)NR, Complexes and the X-ray Ph)NEt,](PPh,) Structure of Ru,(CO),[p-O=CCHC(
R
\
R’”\\
C
,Ph
I
Graham Nigei Mott, Ruthanne Granby, Shane A. MacLaughiin, Nicholas J. Taylor, and Arthur J. Carty’ Guelph- Waterloo Centre for Graduate Work in Chemistry Waterloo Campus, University of Waterloo Waterloo, Ontario, Canada N2L 3G1 Received August 18, 1982
Summary: The multisite bound acetylide in M,(CO)&v2-CsPh)PPh,) (M = Ru, Fe) reacts with CO in the presence of primary and secondary amines NHRR‘ to generate via carbonylation and amination the p-keto (2). compounds M,(CO),[p-O=CCHC(Ph)NRR’](PPh,) X-ray analyses of 2 (M = Ru, R = R’ = Et) and 2 (M = Fe, R = Ph, R‘ = H) revealed the presence of oxygen and carbon bonded acyl groups with regiospecific addition of the amine to the original P-alkynyl carbon atom. These p 0 , C complexes may be closely related to species implicated in the reduction of CO by H, to oxygenates in the presence of binuclear catalysts. The possible use of this reductive carbonylation strategy for the elaboration of other mukisite bound carbocationic ligands is suggested.
The possible involvement of p-bound ligands of the general type 1 (e.g., X = OH, OR) in the nucleophilic activation of carbon monoxide has focused increasing at0276-733318312302-0189$01.50/0
The phosphido-bridged binuclear acetylide Fez(C0)6(p-q2-C=CPh)(PPh2)6 in benzene reacts cleanly with aniline in the presence of carbon monoxide. Infrared monitoring of the reaction mixture showed essentially quantitative replacement of the v(C0) bands of the precursor with those of a single product’ of composition Fe2(C0),-
(1) See, for example: (a) Lin, Y. C.; Knobler, C. B.; Kaesz, H. D. J . Am. Chem. SOC.1981, 103,1216. (b) Butts, S. B.; Strauss, S. H.; Holt, E. M.; Stimson, R. E.; Alcock, N. W.; Shiver, D. F. Ibid. 1980,102,5093. (c) Marsella, J. A.; Folting, K.; Huffman, J. C.; Cadton, K. G. Zbid. 1981, 103, 5596. (d) Maata, E. A.; Marks, T. J. Ibid. 1981, 103,3576. (e) Wolczanski, P. T.; Bercaw, J. E. Acc. Chem. Res. 1980, 13,121. (2)(a) Azam, K. A.; Choo Yin, C.; Deeming, A. J. J. Chem. SOC., Dalton Trans.1978, 1201. (b) Szostak, R.;Strouse, C. E.; Kaesz, H. D. J. Organomet. Chem. 1980,191,243.(c) Adams, R.D.; Golembeski, N.; Selegue, J. P. Inorg. Chem. 1981, 20, 1242. (3)Mayr, A.; Lin, Y. C.; Boag, N. M.; Kaesz, H. D. Inorg. Chem. 1982, 21, 1704. (4)Daroda, R. J.; Blackborow, J. R.; Wilkinson, G. J. Chem. SOC., Chem. Commun. 1980, 1101. (5)See, for example: Collman, J. P.; Hegedus, L. S. “Principles and Applications of Organotransition Metal Chemistry”; University Science Books: Mill Valley, CA, 1980;Chapter 8. (6) Smith, W. F.; Yule, J.; Taylor, N. J.; Paik, H. N.; Carty, A. J. Inorg. Chem. 1977, 16,1593.
0 1983 American Chemical Society
