0 Copyright 1995
Volume 14, Number 72, December 7995
American Chemical Society
Communications An Unusual Hydrogen Migration from a Cyclopentadienyl to a pCarbyne Carbon in the Reaction of Grignard Reagents with
[F~z(CO)Z(C~)Z(C~-CO)(C~-CSM~)ISO~CF~ Vincenzo G. Albano,? Silvia Bordoni,t Luigi Busetto,t Magda Monari,? and Valerio Zanotti*?t Dipartimento di Chimica Fisica ed Inorganica, Universitdc di Bologna, Viale Risorgimento 4, I-40136 Bologna, Italy, and Dipartimento di Chimica %. Ciamician”, Universitci di Bologna, Via Selmi 2, I-40126 Bologna, Italy Received August 9, 1995@
Summary: Reaction of ~Fe~CO~~cp~z(p-COXp-CSMe)lSO~moted by nucleophilic attack a t the CO ligand.5 While CF3 (1;cp = r]-Cdld with Grignard reagents RMgCl (R examining the reactions of dinuclear p-alkylidyne com= benzyl, phenyl, isopropyl) forms the alkylidene complexes with carbon nucleophiles, we have found that pounds [Fez(CO)z(cp)(Cdl4R)(p-CO)@-C(SMe)H}I (2) the reaction of 1 with BzMgCl a t 0 “C forms two and the corresponding cyclopentadiene complexes [Feecompounds which have been separated by chromatog(CO)dcp)(C5H&(p- C0)Cp-CSMe)] (3). The latter comraphy on an alumina column. The nature of the major plexes are the intermediates in the formation of 2 which red product [F~~(CO)Z(C~)(C~H~BZ)(~-CO)~-C(SM~) are formed by hydrogen migration from the C a & ring (2a;40%) has been ascertained by an X-ray structo the p-C carbyne carbon. The molecular structure of tural study, which has shown that C-C bond forma[Fez(CO)z(cp)(C~fiz)(pCO)@-C(SMe)H)I has been detion has occurred at the cp ligand, accompanied by a termined by X-ray crystallography. Spectroscopic prophydrogen migration a t the p-C carbon.6 The y4-pentaerties of the complexes are also presented. dienyl-alkylidyne nature of the second product, [F~Z(CO)Z(~~)(C~H~BZ)(~-CO)(~-CSM~)I (3a;17%),specExtensive investigations on the chemistry of the bridging thiocarbyne complex [Fez(CO)z(cp)z(u-CO)(u- troscopically ascertained, demonstrates well the nucleophilic addition at the cp ring, which is well-known in CSMe)lS03CF3 (1; cp = 77-CsHs)l with nucleophiles mononuclear c~mplexes,~ including iron compounds,* have evidenced several reactivity patterns which inbut, to our knowledge, has never been observed in clude addition a t the p-C carbon,2NCO- insertion into polynuclear species. the p-C-S bond,3 carbonyl s u b ~ t i t u t i o n , and ~ , ~ more It has been previously reported2*that the addition of recently, carbyne-carbonyl migratory coupling proBzMgCl t o 1, at room temperature, results in an exothermic reaction yielding, after silica gel column + Dipartimento di Chimica “G. Ciamician”. * Dipartimento di Chimica Fisica ed Inorganica. chromatography, the alkylidene complex [Fez(CO)z(cp)zAbstract published in Advance ACS Abstracts, November 1,1995. (u-CO)@-C(Me)Bz}l. At this point, it is not clear why (1)Quick, M.H.; Angelici, R. J. Inorg. Chem. 1981,20,1123. @
(2) (a) Schroeder, N. C.; Funchess, R.; Jacobson, R. A.; Angelici, R.
J. Organometallics l989,8,521.(b) Busetto, L.;Bordoni, S.; Zanotti,
V.; Albano, V. G.; Braga, D. Gazz. Chim. Ital. 1988,118,667. (3)Busetto, L.;Carlucci, L.; Zanotti, V.; Albano V. G.; Braga, D. J . Chem. SOC.,Dalton Trans. 1990,243.
(4)Schroeder, N.C.;Angelici, R. J . J.Am. Chem. SOC.1986,108, 3688. (5)Busetto, L.;Zanotti, V.; Norfo, L.; Palazzi, A,; Albano, V. G.; Braga, D.Organometallics 1993,12,190.
0276-7333/95/2314-5455$09.00/00 1995 American Chemical Society
Communications
5456 Organometallics, Vol. 14,No. 12, 1995 Scheme 1
P
oc,
/A\ -Fe,co
Fe
3
the different reaction conditions lead to such different products; however, it seems reasonable that the lower reaction temperature may result in a different reaction pathway, directing the nucleophilic addition at the Cp ring. Reactions of 1 with hydrides are known as well to give different products under different conditions: addition of NaBH4 at room temperature occurred at the bridging carbon? whereas reaction with LiHBEt3 at low temperature involved the carbonyl, affording the alde-
k
Figure 1. Ortep drawing of [Fez(CO)z(cp)(CsHsBz) 40)@-C(SMe)H}l (2a). Selected bond distances ( ) and angles (deg) are as follows: Fe(l)-Fe(2), 2.519(1);Fe(1)CUI, 1.982(3);Fe(2)-C(l), 1.957(3);Fe(l)-C(2), 1.903(4); Fe(2)-C(2), 1.915(3);C(1)-H(l), 0.96(4);C(2)-0(2), 1.171(4); C(3)-0(3), 1.141(4); C(4)-0(4), 1.143(5); C(l)-S, 1.774(3); C(5)-S, 1.761(6); C(l)-S-C(5), 102.4(2); S-C(l)-H(l), 107(2);S-C(1)-Fe(2), 117.8(2);S-C(l)-Fe(l),123.9(2).
hyde complex [F~F~(CO)(C~)Z@-CO)(~~-C(SM~)(CHO))I.~ the metal followed by a rearrangement to the cp ring In order to prove that our findings are of general to yield the endo-RC5Hs isomer. The IR criterion, applicability, we have investigated the reaction with based upon the characteristic absorption of the cycloother Grignard reagents (RMgC1; R = Ph, iR): the pentadiene He, atom around 2750 cm-l, provides a results are consistent with those obtained in the case reliable method for distinguishing between the isoof R = Bz (Scheme 1). mers.ll In our case the absence of the IR C-He,, band Type 2 and 3 complexes have been characterized by suggests that a direct nucleophilic attack at the cp ring spectroscopy (IR and NMR).9J0 The IR spectra of type has occurred. 3 complexes exhibit a v(C0) band pattern (e.g. for 3a Complexes 2a-c exhibit spectroscopic propertiesgJO in CHzCl2 a t 1980 s, 1945 w, and 1790 m cm-') that is similar to those of the previously reported bridgingmconsistent with the presence of two terminal and one ethylidene complexes of the type [Fez(CO)z(cp)2@-CO)bridging CO ligand. One single resonance, attributable (lc-C(R)H)].2aJ2In particular the methylidene proton to the cp group, is observed in both the lH and 13CN M R gives rise to the expected low-field resonance at about spectra (e.g. for 3a signals at 6 4.73 and 86.2). The 6 11 and the methylidene carbon resonance occurs at C5HsR ring carbons, being diastereotopic, give rise tofive about 6 170. One single resonance is observed for the distinct signals in the 13C NMR spectra (e.g. for 3a 6 cp as well as for the SMe group (e.g. for 2a a t 6 4.90 91.1,87.5, 72.2,69.2, and 59.0). The key feature in the and 2.87, respectively), indicating the existence, in 13C NMR spectra of 3 is the low-field resonance (for 3a solution, of a single isomer, presumably that bearing at 6 398.0) in the region typical of bridging thioalthe SMe group on the less hindered CO side of the kylidyne carbons. l s Z a v 5 A direct attack of R- a t the 7,75-CsH5ring normally (9)Synthesis and characterization of 2a and 3a: freshly prepared occurs a t the ex0 side of the ring, affording the L,M-q4BzMgBr (0.29mmol) in thfsolution was added to a stirred suspension exo-RCsH5, unless nucleophilic addition takes place a t of 1(0.14g, 0.26mmol) in thf (15mL) cooled to 0 "C with an external (6)Crystal data for 2a: C ~ ~ H Z ~ F ~fwZ 476.14; O ~ S , triclinic, space group P1 (No. 21,a = 6.833(2)A,b = 7.747(2)A,c = 19.275(3)A, a = 93.26(2)",B = 93.62(2)", y = 100.21(2Y,V = 999.8(4)A3,Z = 2,d(calcd) = 1.582Mg m-3; ambient temperature; crystal dimensions 0.28 x 0.22 x 0.05 mm; graphite-monochromated Mo Ka radiation; p(Mo Ka)= 1.575mm-l. Data were collected on an Enraf-Nonius CAD-4 diffractometer using the w-scan mode; 4350 independent reflections ( M , G , + l ) 0 , = 54" and corrected for absorption using the were collected to 2 identified the azimuthal scan method. Direct methods (SHEIXS-86) positions of the metal atoms and iterative cycles of least-squares refinement (on F),and difference Fourier syntheses located the remaining non-hydrogen atoms. The non-hydrogen atoms were refined anisotropically, and the carbene hydrogen was refined with fixed isotropic displacement parameters. The remaining hydrogen atoms were placed in calculated positions. Refinement on F (SHELXL93) against 4344 data led to final convergence with R1 = 0.0437,wR2 = 0.1191,and S = 1.089(F, > 4uFJ for 232 refined parameters. (7)(a) Davies, S.G.; Green, M. L. H.;. Mingos, D. M. P. Tetrahedron 1978, 34, 3047.(b) Maitlis, P. M. Chem. SOC.Rev. 1981, 10, 1. (8)(a) Treichel, P.M.; Shubkin, R. L. Inorg. Chem. 1967, 6 , 1328. (b) Green, M. L. H.; Whiteley, R. N. J. Chem. Soc. A 1971, 1943.(c) Liu, L. K.; Luh, L. S. Organometallics 1994, 13, 2816.(d) Brown, D. A.; Fitzpatrick, N. J.; Groarke, P. J.; Koga, N.; Morokuma, K. Organometallics 1993, 12, 2521.
ice bath. The mixture was stirred for about 90 min, warmed to room temperature, and then filtered on a n alumina pad. The solution was evaporated under reduced pressure, and the residue was chromatographed on an alumina column with a CHzClz-hexane mixture (1:4, v:v) as eluent. A first green fraction was collected, evaporated to dryness, and crystallized from CHzClz layered with pentane at -20 "C, yielding [F~z(CO)Z(C~)(CSHE.P~)~-CO)~~CSM~)I (3a;CsHd3z = q4benzylcyclopentadiene; yield 50 mg, 40%). Anal. Calcd for C22H20Fe203S: C, 55.50; H, 4.23.Found C, 55.44;H, 4.27.IR (CH2Clz): v(C0) 1980 s, 1945 w, 1790 m cm-l. 'H NMR (CDZC12): 6~ 7.28-7.04( 5 H, 3.09(3H, m, Ph), 4.73( 5 H, 8 , cp), 4.65,4.16,3.70(5H, m, C~HE.BZ), s, Me), 2.08 (2H, d, J = 2 Hz, CHzPh). 13C NMR (CD2C12): 6c 398.0 (br,p-CSMe),265.5gC-CO), 221.7,212.7(CO), 139.8,129.2,128.5, 125.9 (Ph), 86.2(cp), 91.1,87.5,72.2,69.2,59.O(CsHsB~), 50.8(CHzPh), 33.2 (SMe). Further elution with CHzClz-hexane (l:l,v:v) gave a red fraction which yielded, by crystallization, [F~~(CO)~(C~)(CSH~BZ)~~-CO){pu-C(SMe)H}1(2a; 21 mg, 17%; C ~ H ~ B =Z $-benzylcyclopentadienyl). Anal. Calcd for CzzHzoFez03S: C, 55.50;H, 4.23.Found: C, 55.58;H, 4.32.IR (CHzClz): v ( C 0 ) 1981 8,1943w, 1779 m cm-l. lH NMR (CD3CN): 6~ 11.55(1H, s, p-CH), 7.35(5H, m, Ph), 4.90(5 H, s, cp), 4.85, 4.78,4.55 (4H, m, Cad&), 3.90 (1H, d, JAB= 15 Hz, CHzPh), 3.81 (1 H, d, JAB = 15 Hz, CHZPh), 2.87 (3H, s, Me). 13C NMR (CD3CN): 6c 274.1 01-CO), 212.5,212.4 (CO), 171.3 (u-CHSMe), 140.8,128.7, 128.6,126.5(Ph),87.4(~p), 105.9,88.2,86.9,86.7,67.2 (C~H~BZ 33.5 ), (SMe), 25.1 (CHZPh).
Communications
Organometallics, Vol. 14, No. 12, 1995 5457
known16 to occur in connection with light-induced loss molecule. This is the configuration found in the solid of CO. Therefore, it is quite obvious to assume that state for 2a and [F~~(CO)~(C~)~@-CO)(LL-C(SM~)H}I~~ complexes 3 are formed via hydrogen migration from (see Figure 1). The latter structure is strictly compathe cyclopentadiene ligand to the p-thioalkylidyne carrable with that of 2a, the only difference being the bon. Conditions which favor this migration are curbenzyl appendage. rently under investigation: pure samples of 3 in CHzClz The migration of the R group from the metal to the solution do not exhibit appreciable conversion into 2 the cyclopentadienyl ring has been observed in [Fe(cp)after 24 h. The relative amounts of the complexes Band (C0)zRI (for R = COCH3,13 SiMe3,14 Bz15 ). In the 3 does not change appreciably upon chromatography on complex [Fe(q4CsHsBz)(C0)31the opposite transfer of Bz an alumina column; however, we have found that, upon from the cyclopentadiene ring to the iron atom is also treatment with silica gel, the conversion of 3 to 2 (10)2b:IR (CH2C12) v(C0) 1981 s, 1944 w, 1780 m cm-’; ‘H NMR becomes significant. (CDC13) 8~ 10.93 (1H,S, ji-CHI, 7.41-7.19 (5 H, m, Ph), 4.53(5H, s, cp), 5.20,4.95, 4.81,4.67(4H, m, CfldPh), 2.50(3H, 6 , SMe). 3b: IR (CH2C12) v(C0) 1982 s, 1947 w, 1790 m cm-’; ‘H NMR(CDzC12) SH
Acknowledgment. Financial support from the
7.22-6.94(5H,m,Ph),4.20(5H,s,cp),4.87,4.34,3.94,3.71(5H,m, MURST (Minister0 dell’Universith e della Ricerca SciCf15Ph), 2.48 (3 H, s, Me). 2c: IR (CH2C12) v(C0) 1979 6 , 1941 w, entifica) and the CNR (Consiglio Nazionale delle 1779 m cm-l; lH NMR (CDCl3) d~ 11.39 (1 H,S, p-CH), 4.74(5 H, S, CD). 4.90.4.79.4.09 (4H. m. C&&Ph). 2.82(3 ,. H. s. SMe). . ~ ~ . ,2.90 , ~ . (1 ~ . . H. ~ -m. ~ , . . ~ Ricerche) , is gratefully acknowledged. dihlez),’ 1.30’(6H,’d, C H k e z ) ; 13C NMR (CD#lz) 6c 274.2h-CO), 212.7,212.2(CO), 170.3 @-CHSMe), 87.6(cp), 114.2,88.5,87.0,85.3, Supporting Information Available: Listings of crystal 85.2(CsH4iFr),27.3(SMe), 23.5.23.1Wr).3c: IR (CHzClz) v(C0) 1979 s. 1943 w. 1786 m cm-’: ‘H NMR (CDC14 8~ 4.74 (5H: s. CD). 4.63. data, positional and thermal parameters, and bond distances 4.14,3.79 (m, C5HsiPr), 3.13 (3H, s, Me),-l.3i (1H, m, C&ezj, 0.72 and angles for 2a (8 pages). Ordering information is given on (6H, s, br, CHMez). any current masthead page. (11)(a) Davison, A.;Green, M. L. H.; Wilkinson, G. J . Chem. SOC. 1961,3172.(b) White. D. A. Orearmmet. Chem. Rev. Sect. A 1968.3. OM950630N 497.(c) Khand, I. U.; Pauson, P.L.; Watts, W. E. J . Chem. SOC.C 19k9; 2024.(d) Faller, J. W. Inorg. Chem. 1980,19,2857. (14)(a) Berryhill, S. R.; Sharenow, B. J . Organomet. Chem. 1981, (12)Kao, S.C.; Lu, P. P. Y.; Pettit, R. Organometallics 1982,1,911. 221, 143. (b) Berryhill, S. R.; Clevenger, G. L.; Burdurlu, F. Y. (b) Casey, C. P.; Fagan, P. J.; Miles, W. H. J. Am. Chem. SOC. 1982, Organometallics 1985,4, 1509. 104,1134.(c) Aime, S.; Cordero, L.; Gobetto, R.; Bordoni, S.; Busetto, (15)Blaha, J. P.; Wrighton, M. S. J. Am. Chem. Soc. 1985,107,2694. L.; Zanotti, V.; Albano, V. G.; Braga, D.; Grepioni, F. J . Chem. Soc., (16)Zou, C.;Wrighton, M. S.;Blaha, J. P. Organometallics 1987,6, Dalton Trans. 1992,2961. 1452. (13)Liebeskind, L.S.;Welker, M. E. Organometallics 1983,2,194. ~I ~
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