Organometallics 1995, 14, 4325-4333
4325
Substitution Reactions of a p-Thioether Ligand in Dinuclear Cyclopentadienylmolybdenum Complexes D. S. Tucker, S. Dietz, K. G. Parker, V. Carperos, J. Gabay, B. Noll, and M. Rakowski DuBois* Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309
Charles F. Campana Siemens Industrial Automation, 6300 Enterprise Lane, Madison, Wisconsin 53719 Received February 27, 1995@ The thermal reaction of the thioether-bridged complex [(CpMo)z(SzCHz)Cu-SMe)Ol-SMe2)]OTf (1) with electron donors leads to the elimination of dimethyl sulfide and the formation of structures which incorporate new ligands into the dimer. For example, reaction of 1 with excess LiCl results in the formation of (CpMo)z(SzCH2)(~-SMe)Cu-C1)(2), which has been isolated and characterized by an X-ray diffraction study. Dimers with p-bromide and with p-q2-alkyne ligands have also been prepared by thioether substitution reactions and characterized spectroscopically. The reaction of 1 with two-electron donors led to the formation of dimers with new terminal ligands of the formula [(C~MOL)~(S~CH~)C~-SM~)]OT~ with L = tBuNC (6a),CsHsCHzNC (6b),and CO (7).The X-ray diffraction study of one isomer of 7 established that the cation contained cis carbonyl ligands and an equatorial configuration for the methanethiolate substituent. The complexes with terminal isocyanide ligands are thermally stable, but the complex with carbon monoxide ligands undergoes ligand exchange reactions a t high temperatures. The potential reactivity of the carbon monoxide ligands in 7 with nucleophiles and with oxidants has been explored. For example, the reaction of 7 with Me3NO in acetonitrile solution results in the loss of one carbonyl ligand and the formation of [CpMo(CO)(S2CH2)(p-SMe)(MeCN)MoCplOTf (91, a potential precursor to coordinatively unsaturated complexes.
Introduction We have recently reported the synthesis of dinuclear cyclopentadienylmolybdenum complexes with a p-thioether ligand, e.g., [(C~MO)~(S~CH~)C~-SM~)C~-SM~~)~OT~ (11.l The thioether ligand in 1 is thermally labile, and 1 s-r when the thermolysis in a sealed tube was followed by NMR spectroscopy, evidence for a reversible process was observed (eq 1).
c;,
Me
v
n The three-sulfur product may involve some stabilization by solvent coordination, but this intermediate has not been successfully isolated or characterized. Nevertheless, reaction 1has been used in the synthesis of new thioether complexes via substitution of the labile bridge with a free dialkyl sulfide. In addition, thermal reactions of 1 with cyclic thioethers have led to a number of desulfurization reactions, as shown in eq 2.l More recently we have extended the ligand substitution chemistry of 1 to synthesize molybdenum complexes which contain new types of ligands in the dinuclear structure. Thermal reactions of 1 with atoms or groups @Abstractpublished in Advance ACS Abstracts, August 15, 1995. (1)Gabay, J.; Dietz, S.; Bernatis, P.; Rakowski DuBois, M. Organometallics 1993,12, 3630.
which can act as four-electron donors lead to products with new bridging ligands, while conventional twoelectron donors serve as terminal ligands at each metal center. This paper reports the syntheses and characterizations of several examples of these new derivatives.
Results and Discussion Synthesis of p-Halide Derivatives. A chloride anion is similar in size and electronegativity t o a thiolate sulfur, and substitution of this halide into the dinuclear molybdenum structure was expected to be facile. The reaction of 1 with excess lithium chloride was carried out in refluxing acetonitrile. Two products were formed in the reaction as shown in eq 3. An analogous reaction was also characterized for the MeCp derivatives.
Q276-7333/95/2314-4325$09.Q~IQ0 1995 American Chemical Society
Tucker et al.
4326 Organometallics, Vol. 14, No. 9,1995
8
Table 1. Selected Bond Distances and Angles for
(CPMo)z(SaCHz)~.SCHs)Ol-Cl) (2) Distances (A) Mo(l)-M0(2) Mo(l)-S(2) Mo(l)-C1(1) Mo(l)-S(l) Mo(l)-S(3) S( 1)-C( 1)
2.610(2) 2.435(4) 2.508(4) 2.462(4) 2.411(4) 1.77(2)
Mo(l)-S(l)-M0(2) Mo(l)-S(2)-M0(2) Mo(l)-S(3)-M0(2) Mo(l)-Cl(l)-M0(2) Mo(l)-S(3)-C(3)
Figure 1. Perspective drawing and numbering scheme for (CpMo)z(SzCHz)gl-SMe)~-C1')(2). Thermal ellipsoids are shown at the 50% probability level.
Angles (deg) 64.18(11) Mo(l)-S(l)-C(l) 65.11(12) M0(2)-S(l)-C(l) 64.99(11) Mo(l)-S(2)-C(l) 62.77(10) Mo(2)-S(2)-C(l) 108.0(7) Mo(2)-S(3)-C(3)
~
H
1
H
~ 2
H
H"H
3
2.450(4) 2.415(4) 2.447(4) 2.504(4) 1.91(2) 1.79(2) 93.9(6) 93.7(6) 91.5(5) 91.5(5) 111.2(7)
Table 2. Atomic Coordinates ( x lo4) and Equivalent Isotropic Displacement Parameters (A2 x lo3)for C I ~ H ~ ~ S ~(2) C~MO~ X
H
M0(2)-S(1) M0(2)-S(2) M0(2)-s(3) M0(2)-C1(1) S(2)-C(1) S(3)-C(3)
1149(1) 200(1) 6297(1) 5107(1) -26(3) 1618(3) 1362(3) 5065(3) 6749(3) 6368(3) -429(3) 4702(3) 854(13) 7242(11) 2500( 13) 5538(12) 2057(20) 1297(16) 1384(14) 2172(15) 2588(13) 291(12) - 72(12) -931(14) -1172(12) -427(12) 7795(13) 7608(11) 6867(12) 6628(14) 7176(15) 4191(18) 4872(16) 4631(17) 3859(19) 3582(18)
Y
1750(1) 3158(1) 1550(1) 1066(1) 1529(3) 2495(3) 3351(3) 329(3) 450(3) 2271(3) 2296(3) 2333(3) 1627(12) 1412(11) 3769(15) -821(11) 1184(17) 523(16) 158(13) 551(13) 1206(14) 4444(12) 4785(13) 4363(12) 3709(12) 3794(12) 1967(13) 1143(12) 1327(13) 2270(15) 2675(13) 1426(16) 746(17) -52(14) 108(20) 990(24)
z
UWa
4714(1) 3879(1) 153%1) 2577(1) 334x31 3431(3) 5248(3) 1153(3) 2737(3) 2993(2) 5078(3) 1462(3) 2656(11) 3525(10) 5034(14) 1276(11) 5981(14) 5735(16) 4915(15) 4697(15) 5354(16) 3031(11) 3755(12) 3792(12) 3056(11) 2586(10) 1416(11) 916(10) 202(11) 273(11) 1026(12) 3583(18) 3960(12) 3461(17) 2837(16) 2906(19)
The chloride-bridged derivative 2 was the major product, but approximately 20% of the material was converted to the neutral bis(thio1ate) derivative, which has been prepared previously.2 Methyl chloride is presumably a byproduct in the formation of the bis(thiolate) product, but efforts to detect this volatile species were not made. The demethylation of 1 by nucleophiles has been characterized previously, however. For example, reaction of l with cyanide ion in DMSO was found to produce 3 and acetonitri1e.l The neutral complexes 2 and 3 were difficult to separate, but 2 could be isolated in pure form as dark green crystals by recrystallization at low temperatures. The mass spectrum of 2 was consistent with the proposed formulation, and the lH NMR spectrum suggested that the single chloride ligand occupied a symmetrical bridging position. Two isomers of the product were apparent in the spectrum, and these are attributed to slow inversion at the thiolate sulfur. A single crystal was isolated from a hexane/CHzClz solution and characterized by an X-ray diffraction study. Two molecules were observed per asymmetric unit. The structural features were very similar, and an Ortep plot of one of the molecules is shown in Figure 1. Selected bond distances and angles are given in Table 1and positional parameters in Table 2. The product contains a molecular (but not a crystallographic) plane of symmetry perpendicular to the metal-metal vector with the chloride and three thiolate sulhr bridges lying in this plane. The average Mo-S thiolate bond distance, 2.439(4) A, is very similar to those observed for the neutral bis-
(thiolate) analogue 3.2 The average Mo-C1 distance of 2.495(4) A is slightly longer than the Mo-S bonds, but the value is similar to the Mo-C1 distance of 2.484(1) A reported for the related Mo(II1) dimer [R-CpMo@-C1)212.3 The longer M-C1 distance results in an average Mo-C1-Mo angle of 63.08(10)" in 2, compared to the average Mo-S-Mo angle of 64.70(11)". The redox properties of 2 were studied by cyclic voltammetry. Complex 2 was found to undergo a reversible oxidation a t -0.29 V vs Fc (AE,= 80 mV) and a second well defined quasi-reversible oxidation at f0.32 V vs CpzFe (AI3 = 140 mV). The facile two-
(2) McKenna, M.; Wright, L. L.; Miller, D. J.;Tanner, L.; Haltiwanger, R. C.; Rakowski DuBois, M. J . Am. Chem. SOC.1983, 105, 5329.
(3) Green, M. L. H.; Izquierdo, A,; Martin-Polo, J. J.; Mtetwa, V. S. B.; Prout, K. J. Chem. SOC.,Chem. Commun. 1983, 538.
a U,,is defined as one-third of the trace of the orthogonalized U,j tensor.
Substitution Reactions of a p-Thioether Ligand electron-oxidation behavior is similar t o that of the series of neutral Mo(II1) dimers which contain fourbridging thiolate ligand^.^ For example, under similar conditions oxidation waves were observed for 3 at -0.36 V (a, = 90 mV) and at f0.35 V (AE,= 100 mV) vs CpzFe. The one-electron-oxidationproduct of 2, [(CpMoh(SzCHz)@-SMe)@-Cl)IOTf, could be isolated as a purple solid from the reaction of 2 with 1equiv of silver triflate. The FAB+ mass spectrum showed envelopes at mle values identical with those observed in the E1 spectrum of 2. We were curious whether the mixed-valence derivative might show enhanced lability in ligand substitution reactions, but a reaction with LiNEt2, for example, resulted in rapid electron transfer and regeneration of 2. Ligand substitution reactions have been observed for 2 under thermal conditions. For example, 2 reacted with excess LiBr in refluxing acetonitrile to form (CpMo)2(S2CHz)@-SMe)@-Br) (4) (eq 4). 'H NMR reso-
;> 4.OdF)) 10 195 (F > 4.0a(F)) no. of obsd rflns final residuals (obsd data)" R1 0.0715 0.0669 wR2 0.1670 0.1345 goodness of fit 0.990 1.140 largest diff peak, e/A3 1.579 1.455 largest diff hole, e/A3 -1.060 -0.651 - IFcll}EIFoI; wRz = {C.[W(FO' - FC2)211'21/ a Ri = {CIIFol {1W(F02)211.
b, A
14.084(2) 14.151(2) 15.419(3) 100.17(3) 3024.8(8)
dissolved in Et20 (2 x 5 mL) and chromatographed on neutral alumina with hexanes (80 mL), removing a clear band, which was discarded. Elution with Et20 (200 mL) afforded a green band containing both products. Slow cooling of a 5:l hexanes/EtzO solution of the product mixture to -70 "C afforded green crystalline 2. 'H NMR (CDClS): 6 5.77, 5.76 (2s, 10 H, Cp, two isomers), 5.41, 5.34 ( 2 ~ 2, H, S2CH2), 1.49, 1.47 ( 3 ~ 2, H, SCH3). 13C('H}NMR (CDCl3): 6 93.79 (s,Cp), 74.60 (s,S2CH2), 22.77 (5, SCH3). MS (EI+;d e ) 482 (PI, 467 (P - CHd, 436 (P - CH3 - S), 421 (P - CH3, S - CH2). Oxidations in acetonitrile with 0.1 M (n-Bu14NBF4 (V vs CpaFe): Eo = -0.29, AE = 80 mV, E" = 0.37, AE = 240 mV. Experimental Section A similar procedure was followed to prepare (MeC~MO)~(S~CH~)C~-SCH~)C~-C~). 'H NMR data (CDC13; Reactions were carried out under a nitrogen atmo6): 5.79-5.57 (10 H, m, Cp, CH2); 2.02 (6 H, s, MeCp); sphere using standard Schlenk techniques. Solvents 1.49, 1.35 (3 H, s, SCH3). MS (EI; d e ) : 510 (PI, 495(P were dried and degassed before use. The molybdenum - Me), 463 (P - SMe), 449 (Cp'MoS)2Cl). Anal. Calcd complexes [C~MO)~(S~CH~)(SM~)C~-SM~~)IOT~ and [(Mefor C ~ M O ) ~ ( S ~ C H ~ ) C ~ - S M ~ )were C ~ -synthesized S M ~ ~ ) ~ O T ~ C14H19ClM02S3: C, 32.92; H, 3.75; C1, 6.94; S, 18.83. Found: C, 32.98; H, 3.62; C1, 6.88; S, 18.49. according t o published pr0cedures.l X-ray Diffraction Study of (CpMoMS2CHd@(C~MO)~(S~CH~)(I~-SCH~)@-C~), 2. [(CpMo)z(SzSMe)@-Cl)(2). The complex was crystallized by coolCH2)Cu-SCH3)Cu-S{CH3}2)lOTf (1;0.078 g, 0.12 mmol), ing a saturated hexane/methylene chloride solution (5: LiCl (0.18 g, 4.1 mmol), and CH3CN (20 mL) were 1). The product crystallized in space group P2dc with combined in a Schlenk flask. The solution was heated two molecules per asymmetric unit. Data were collected to reflux for 11 h, while the color changed from orange on a Siemens P3/F diffractometer. The molybdenum to green. Solvent was removed in vacuo, affording a positions were determined by direct methods, and the 4:l mixture of 2 and ( C ~ M O ) ~ ( S Z C H Z ) C ~ -(S3)C.H ~ ) ~ other atoms were located using difference Fourier Yield: 0.093 g, 62%. The green solid product was calculations in SHELX. All hydrogens were refined in fixed ideal positions. All non-hydrogen atoms were (11)(a)Brunner, J.; Langer, M. J . Organomet. Chem. 1973,54,221. refined anisotropically during the final cycles of full(b) Whitesides, T. H.; Shelly, J. J . Organomet. Chem. 1975, 92, 215. (c) For other references to nucleophilic attack on Cp ligands, see: matrix least-squares refinement. The chloride atoms Kirchner, K.; Taube, H. J . Am. Chem. SOC.1991, 113, 7039 and were assigned on the basis of chemical evidence. The references therein. largest difference peak was 1.58 elA3 and is 1.15 A from (12)Lawrence, G. A. Chem. Rev. 1986, 86, 17.
4332 Organometallics, Vol. 14, No. 9, 1995
Tucker et al.
6) 5.69 (s, 10 H, Cp), 5.43 (9, 2 H, S2CH2); 1.57 (s,3 H, S6. Details of the crystal data and experimental condiSCH3); 1.36 (s, 18 H, t B ~ ) .13C(lH}NMR (CD3CN; 6) tions and a summary of the solution refinement infor93.03 (C5H5);75.90 (S2CH2);30.81 (CMe3);26.40 (SCH3). mation are given in Table 5 and in the supporting MS mle 613 (P - On?, 532 (P - CNtBu - On?, 447 (P information. - 2CNtBu - OTf), 432 (P - 2CNtBu - CH3 - OTf). (CpMo)z(SzCH2)@-SCHs)@-Br)(4). Method a. Anal. calcd for C I B H I ~ S ~ O ~ F ~CM36.22; O ~ : H, 4.36. Complex 1(0.021g, 0.032 mmol) LiBr (0.30 g, 3.4 "01) Found: C, 36.02; H, 4.40. and CH3CN (15 mL) were combined in a Schlenk flask. The solution was heated to reflux for 16 h while the color [(C~MO(CNB~)}~(S~CH~)@U-SCH~)IOT~ (6b). Complex 1 (0.015 g, 0.023 mmol), CH3CN (10 mL), and CNBz changed from orange to green. Solvent was removed (0.24 mL, 1.0 mmol) were combined in a Schlenk flask. in uucuo. Extraction of a green solution with hexanes (2 x 50 mL) afforded a 3:2 mixture of 4 and (CpMo),The solution was heated to reflux for 11 h, while the color changed from orange to red. Solvent was removed (3). Yield of 4: 0.014 g, 50% yield. (S2CH2)(pu-SCH3)2 in uucuo, affording red solid 6b. 'H NMR (CDCl3; 6) Method b. [(C~MO)~(S~CH~)~~-SCH~)C~] (2; 0.010 g, 7.32 (m, 6 H, Ph); 7.15 (m, 4 H, Ph); 5.53, 5.51 (2s, 10 0.021 mmol), LiBr (0.10 g, 1.1mmol), and CH3CN (15 H, Cp, two isomers); 5.41, 5.40 (29, 2 H, S2CH2, two mL) were combined in a Schlenk flask. The solution isomers); 1.58, 1.59 (2s, 4 H, CNCH2Ph);2.50, 1.57 (2s, was heated to reflux for 16 h. Solvent was removed in 3 H, SCH3, two isomers). uucuo. A lH NMR spectrum of the product showed 31% conversion of 2 to 4. CH3CN (15 mL) was added to the [{C~MO(CO)}~(S~CH~)@-SC&)]OT~ (7). Complex product, and the mixture was heated to reflux for 6 days. 1(0.044 g, 0.067 mmol) and CH3CN (20 mL) were added A IH NMR spectrum of the product mixture showed 86% to a 100 mL high-pressure vessel equipped with a conversion of 2 to 4. 'H NMR (CDCl3; 6) 5.74,5.71 (29, pressure gauge, an inlet for CO, and an inlet for Nd 10 H, Cp, two isomers); 5.46,5.34 (2s, 2 H, S2CH2); 1.51, evacuation. The vessel was evacuated and backfilled 1.50 ( 2 ~3, H, SCH3). with CO (cp grade) three times and finally filled with CO to 150 psi. The solution was heated t o 100 "C for [(CpM0)2@2l-Butyne)(SzCH2)@-SCHs)lOTf(5a). 14 h. The final color was orange. Solvent was removed Complex 1 (0.044 g, 0.067 mmol) and CH3CN (15 mL) in vacuo, affording 7. Yield: 0.043 g, 0.066 mmol, 98%. were added to a 100 mL high-pressure vessel equipped Recrystallization via slow cooling of a CHzCl2 solution with a pressure gauge, an inlet for l-butyne, and an of 7 to -70 "C gave orange cubes. IR (CH2C12): YCO 2010 inlet for Ndevacuation. The vessel was evacuated and (s) cm-l. lH NMR (CDCl3; 6): isomer identified by backfilled with l-butyne (cp grade) and finally filled X-ray diffraction study, 6.08 (s, 10 H, Cp), 5.43 (s, 2 H, with l-butyne to 30 psi. The solution was heated to 98 SzCHz), 1.63 (s, 3 H, SCH3); second isomer 6.10 (s, 10 "C for 11h. The final color was orange-yellow. Solvent H, Cp), 5.47 (9, 2 H, SzCHz), 2.60 (s, 3 H, SCH3). was removed in uucuo, affording orange-yellow solid Sa 13C{'H}NMR (CD3CN; from crystals of one isomer, 13C(0.044 g, 0.067 mmol). Recrystallization from slow enriched CO; 6): 231.72 (5, CO), 95.11 (s, C5H5), 71.69 addition of Et20 to a CH2C12 solution of 5a gave yellow (s, CHd, 23.79 (5, CH3). MS mle 503 (P - OTf), 447 (P needles. 'H NMR (CDC13; 6) 6.08, 6.07 (24 10 H, Cp, - 2CO - OTf), 431 (P - 2CO - CH3 - OTf), 399 (P two isomers); 6.00, 5.63 (2s, 1 H, HC=); 4.97, 4.77 (2s, 2CO - SCH3 - On?. Reduction potential in acetonitrile 2 H, S2CH2); 2.89, 2.80 (29, J = 8 Hz, 2 H, CH2CH3); with 0.1 M (n-Bu)dNBFd: E" = -1.47 V vs FeCpz, A23 1.72, 1.70 ( 2 ~3, H, SCH3); 1.12, 1.11(2t, J = 8 Hz, 3H, = 80 mV. Anal. Calcd for C15H15S305F3Mo2: C, 27.62; CHzCH3). MS: mle 501 (P - OTf), 447 (P - C4H6 H, 2.32. Found: C, 27.58; H, 2.30. OTf), 401 (P - C4H6 - SCH3 - OTf). Anal. Calcd for C ~ ~ H ~ I S ~ O ~C,F31.39; ~MO H,~3.25. : Found: C, 31.35; X-ray Diffraction Study of [(CpMoC0)2(SzCH2)H, 3.36. @-SMe)lOTf,(7). The complex was crystallized from a CHzCldpentane solution and isolated as red-orange [ (CpMo)z(pz-Phenylacetylene)(S2CH2)( p needles, Data were collected on a Siemens SMART SCHdlOTf (5b). Complex 1 (0.120 g, 0.182 mmol), CCD-based diffractometer with an LT-2 low-temperaCH&N (20 mL) and phenylacetylene (1.5 mL, 14 mmol) ture apparatus operating at 173 K. The needle direction were combined in a Schlenk flask. The solution was of the crystal coincided with the u axis of the unit cell. heated t o reflux for 16 h, while the color changed from A total of 1320 frames were collected as 0.3" w oscillaorange to orange-yellow. Solvent was removed in uacuo, tions, each exposed for 10.0 s. The maximum resolution affording orange-yellowsolid 5b. Attempts to recrystalwas 0.90 A. lize this product by slow cooling in a variety of solvents (CH2C12, CH2C12/THF, and CH2Clflt20) as well as by This specimen was originally indexed as monoclinic slow diffusion of pentane into a CHzClz solution of Sb P2, with cell dimensions, u = 10.265 A, b = 14.233 A, c were unsuccessful. Yield: 64%. 'H NMR (CD3CN; 6) = 29.308 A, and 4 , = 99.95". Although the structure was 7.34, 7.22 (2m, 5 H, Ph, two isomers); 6.24, 6.06 (2s, 1 successfully solved using these parameters, refinement H, HCCPh); 6.15, 6.14 (2s, 10 H, Cp); 4.90, 4.74 (2s, 2 was unsatisfactory. The crystal may also be indexed H, S2CH2); 1.76, 1.75 (2s) 3 H, SCH3). as orthorhombic C,but this did not resolve problems with refinement. Oscillation images viewed during data [(CpMoz(CNtBu)}2(S2CH2)@-SCHs)IOTf, (6a). Complex 1 (0.040 g, 0.061 mmol), CH3CN (20 mL), and collection indicated that twinning may be present. Conversion of the primitive monoclinic cell to the CNtBu (0.10 mL, 0.89 mmol) were combined in a unconventional, but equivalent, B-centered cell reported Schlenk flask. The solution was heated to reflux for 14 herein facilitates refinement of the crystal structure as h, while the color changed from orange to red. Solvent a pseudo-orthorhombic twin by bringingp nearer to 90". was removed in uucuo, affording red solid 6a. RecrysThe twin lattice is related to the indexed lattice by the tallization by slow addition of Et20 to a CHzClz solution matrix [1,0,0,0,-1,0,0,0,11. The ratio between the two of 6a gave red plates. Yield: 64%. IR (CH2C12): VCN components in this specimen is 0,109 91. Careful 2108 (SI, 2068 (sh), 2034 (sh) cm-l. lH NMR (CD3CN;
Organometallics, Vol. 14, No. 9,1995 4333
Substitution Reactions of a p-Thioether Ligand
(Cp CHd, 23.78 (SMe). The FAB+ mass spectrum for examination of the data did not reveal the presence of the product was similar to that observed for the starting higher symmetry. Solution and refinement were perreagent 7. formed with the SHELXTL suite of programs.13 Details of the crystal data and experimental conditions and a [ ( C ~ M O ) ~ ( C ~ ) ( C H ~ C N ) ( S ~ C H ~ )(9). ( ~ ~A- S C ~ ) I O ~ summary of the solution refinement information are THF (20mL) solution of Me3NO (0.04g, 0.06 mmol) was given in Table 5 and in the supporting information. added to an orange THF (20mL) solution of [(CpMoCO)zSynthesis of CpMo(CO)(lr-S,CHz)(lr-SMe)(CO)-(S~CH~)(U-SCH~)]OT~ (7;0.042 g, 0.062 mmol) over 15 MoCsH6, (8). LiBEt3H (70pL, 0.070mmol) was added min. The resulting solution was yellow. Solvent redropwise to a solution of 7 (50 mg, 0.077 mmol) in 10 moval gave a yellow solid. Recrystallization via slow mL of dry, degassed tetrahydrofuran with stirring. The addition of toluene to a CH3CN solution of 4 afforded original brown-orange solution immediately turned pale dark orange needles. IR (CH2Ch): vco 1979 cm-l. IH orange; the reaction mixture was stirred for an adNMR (CD2C12); 6) 6.03 (s,5 H, Cp); 5.68 (s, 5 H, Cp); ditional 15 min. The solvent was removed in vacuo, and 5.88(d, 'J = 7.9 Hz, 1 H, S2CH2), 5.07 (d, 2J= 7.9 Hz, the oily, orange residue was extracted with hexanes. The 1 H, S2CH2); 2.42(s,3 H, CH3CN); 1.67(5, 3 H, SCH3). hexane solvent was removed in vacuo to give the solid MS (FAB): mle 518 (P - OTO, 476 (P - NCMe - OTO, orange product. In some cases the product was further 448 (P - NCMe - CO - OTf), 403 (P - NCMe - CO purified by chromatography on neutral alumina, first SMe - OTO. The complex decomposed slowly in the with pentane and then with ether as eluent to obtain a solid state under nitrogen, and elemental analyses were yellow band. Yield: 25 mg, 60%. T w o isomers were not attempted. observed in the NMR spectrum in a 2:l ratio. lH NMR (CDC13; 6): major isomer, 5.85 (9, 5 H, Cp), 5.84,5.69, Acknowledgment. This work was supported by a 3.82,3.40 (4m, C4H41, 4.98 (AB, S2CH2), 3.62 (AB, Cp grant from the National Science Foundation. CH2), 1.63 (s, SCH3); minor isomer, 5.73 (s, 5 H, Cp), 5.60,5.3O74.l2,3.91(4m, C4H4), 4.9(SzCHz),3.93(AB, Supporting Information Available: Complete tables of Cp CH2), 1.30(SMe). 13CNMR (6): major isomer, 91.33 crystal data and refinement details, bond lengths and angles, (C5H5),82.2,82.0,65.0,64.2 (C4H4),65.06(S~CHZ), 40.41 anisotropic displacement parameters, and hydrogen atom (Cp CHd, 24.95 (SMe); minor isomer, 91.88 (C5H5), coordinates for 2 and 7 (21 pages). Ordering information is 83.15,81.90,72.03,71.68(C4H4), 67.63 (SzCHz),47.42 given on any current masthead page. (13) Sheldrick, G . M. SHELXTL; Siemens: Madison, WI, 1995.
OM950156L
