Organometallics 1986, 5 . 582-584
582
Communications Carbonyl Substitution and Ring Slippage upon Reaction of Trialkylphosphines with (Fulva1ene)dlrutheniurn Tetracarbonyi. X-ray ~ ) R U ( and Structural Analysis of ( V ~ : ~ ~ - C , ~ H PMe,),CO Fluxional Behavior of (qJ:v5-C,oH,)R~,(CO)3L(L = Phosphine) Roland Boese,+William B. Tolman, and K. Peter C. Vollhardt'$ Department of Chemistry, University of California, Berkeley and the Materials and Molecular Research Division Lawrence Berkeley Laboratory Berkeley, California 94720 and the Institut fur Anorganische Chemie Universitat Essen-GHS 0-4300 Essen- 1, Postfach 103764, West Germany Received September 30, 1985
Summary: Treatment of (q5:q5-fulvalene)diruthenium tetracarbonyl [FvRu,(CO),, 31 with a large excess (8-10 equiv) of PMe, at 120 OC provides trans -Ru(CO),(PMe,), (7) and FvRu(PMe,),(CO) (6), in which only one Cp ring is bonded to Ru. Complex 6 was characterized by X-ray crystallography: orthorhombic, a = 1464.3 (4) pm, b = 1535.1 (2)pm, c = 1691.6 (4)pm, space group Pbca. Reaction of 3 with 2-3 equiv of PMe, or excess (5 equiv) PEt, gives FvRu,(CO),L (4, 5). Both substitution products are fluxional on the NMR time scale and a mechanism involving reversible terminal to bridged carbonyl exchange is proposed. Activation parameters for the process were determined from a line-shape analysis of variable-temperature 13C NMR spectra of '3CO-labeled 5.
The ligand-induced cyclopentadienyl (Cp) ring slippage reaction has only recently been unambiguously established.' We have been interested in the chemistry of carbonyl ( ~ ~ : ~ ~ - f u l v a l e n e ) d i m(FvM,) e t a l complexes,2 in which linked Cps bridge the two metals. We have reported on the reaction of strongly donating phosphines (PMe3, Me,PCH,PMe2) with F v M o , ( C ~ ) , .The ~ ~ initial product, the novel dinuclear organometallic zwitterion 1 (characterized by X-ray analysis), was found to convert further with phosphines to yield compounds 2 (characterized spectroscopically), which contain a fulvalene ligand with an uncomplexed Cp ring. Here we report the thermal reactions of trialkylphosphines (PR,; R = Me, Et) with FvRuz(CO), (3)2ato give the substitution products 4 and 5 as well as the decomplexed system FvRu(PMe&CO (6), the first of its kind to have been characterized by an X-ray structural investigation. Whereas FvMo,(CO), readily reacts with PMea a t room temperaturezd to give 1, 3 transforms only under more vigorous conditions (8-10 equiv of PMe,, -0.3 M, 120 "C, THF, sealed tube, 22 h) to give two major products, trans-Ru(PMeJ2(CO), (7)3and 6 (l:l,89% yield),4and a small amount ( < 5 % ) of FvRu,(CO),(PMeJ (4)* (Scheme
'Universitat Essen-GHS.
* University of California, Berkeley. 0276-7333/86/2305-0582$01.50/0
oc OC-
GO
1:
Moo
( L =P M e 3 , 1 / 2 M e 2 P C H 2 P M e 2 ) I
2
I). When the reaction was monitored by 'H NMR spectroscopy, only starting material and products were observed; there was no evidence for the expectedzdzwitterion (Fv[Ru(CO),-][ R U ( P M ~ ~ ) ~ C O To + ]test . whether 4 is an intermediate in the formation of 6 , 4 was subjected to the same reaction conditions and did indeed give 6, albeit at a lower rate (50% conversion after 22 h; 'H NMR). Moreover, in addition to 6, Ru(PMe,),(CO), (S)4 formed instead of 7, indicating that 4 cannot be a primary intermediate between 3 and 6. Compound 6 can be formulated as a Ru(0) diene complex (a, Scheme I) or, in the other extreme, as a dipolar species (b) containing a cyclopentadienide ring and a cationic Ru(I1) fragment. The average position of the uncomplexed ring resonances in the I3C NMR spectrum (120 ppm) is intermediate between those of fulvalene (135 ~ p mand ) ~the cyclopentadienide anion (103 ppm),6 suggesting contributions from both resonance forms. In addition, the observation of facile H-D exchange (room temperature, acetone-d,) into the uncomplexed ring supports a significant contribution of 6b. Because of its novelty, an X-ray structural investigation was performed on 6, (Figure 1). The intermediate nature of 6 between extremes 6a and 6b is also reflected in its structural details. Consistent with a Ru(0) diene complex, the atoms C(2), C(3),C(4), and C(5) are within a plane with C(1) 15 pm above it and with an envelope angle of 8.3O. There is a slip of 19 pm of Ru(1) toward C(3) and C(4) relative to the idealized midpoint of the coordinated ring. Consequently the Ru(l)-C(l) bond is the longest ruthenium-carbon bond of the ring. The planar noncoordinated Cp and the plane C(l),C(2),C(5) are close to coplanar with a twist angle of 6.2". Additionally, the C(l)-C(6) bond length (142.7 pm) is shorter than a C-C single bond. Nevertheless, in a pure diene (1) Casey, C. P.; O'Connor, J. M.; Haller, K. J. J . Am. Chem. SOC.1985, 107, 1241 and references therein.
(2) (a) Vollhardt, K. P. C.; Weidman, T. W. J . Am. Chem. SOC. 1983, S.; Tilset, M.; Vollhardt, K . P. C.; Weidman, T. W. Organometallics 1984,3,812. (c) Drage, J. S.; Vollhardt, K. P. C. Ibid. 1985,4,191, and in press. (d) Tilset, M.; Vollhardt, K. P. C. Ibid., in press. (3) Jones, R. A.; Wilkinson, G.; Galas, A. M. R.; Hursthouse, M. B.; Malik, K . M. A. J . Chem. SOC.,Dalton Trans. 1980, 1771. (4) All new compounds gave satisfactory spectral and analytical data (see supplementary material). X-ray determination of 6: crystal size 0.32 X 0.27 X 0.20 mm, orthorhombic Laue symmetry, space group Pbca, a = 1464.3 (4) pm, b = 1535.1 ( 2 ) pm, c = 1691.6 (4) pm, a = /3 = y : 90°, V = 3.803 (1) X IO9 pm3, fiCalcd = 9.71 cm-', dealcd = 1.43 g ern-', radiation Mo K a ( A = 0.71073 A), scan range 3" 5 28 5 65', reflections collected 6667, unique 3486 with F,, t 2.5u(F) empirical absorption correlation applied, R = 0.051, R, = 0.044. (5) Rutsch, W.; Escher, A,; Neuenschwander, hl. Chimia 1983,37,160. (6) Spiesecke, H.; Schneider, W. G. Tetrahedron Lett. 1961,468. 105, 1676; Organometallics 1984, 3, 82. (b) Drage, J.
C 1986 American Chemical Society
Organometallics, Vol. 5, No. 3, 1986 583
Communications Scheme I r
I
4 +
/
Me P
P M e 3 ( 8 - IO equiv.),
- trons - Ru ( P M e 3 ) 2 ( C 0 ) 3 ( 7 )
R'
1
\*
'PMe3
-
J
I
@ Ru.. Me3P'
co
L
1
a
A
co
'PMe3
b
6
OC
_,.Ru-
Ru
oc
"'co co
A
1
\
L(PMe3, 2-3equiv.;
3
PEt3,
Sequiv.)
\
/
Ru-Ru-
co-"l A "L co co 4 5
( L = PMe3) ( L = PEt3)
Scheme I1
OC---R~-R~-,, II
A
oc2
Ic oa
PR3
, =
[TI OC
-Ru-
Ru
-P R 3
4
RU
oc--*A
OCX
- Ru.-
A
-coy
PR3
Table I. Selected Bond Distances in 6 (pm)
61
Ru(l)-C(l) Ru(l)-C(2) Ru(l)-C(5) Ru(l)-C(4) Ru(l)-C(3) Ru(l)-C(17) Ru(l)-P(l) Ru(l)-P(2)
242.8 (4) 225.6 (4) 227.3 (4) 220.6 (4) 219.9 ( 5 ) 183.7 (4) 231.1 (1) 231.1 (1)
C(17)-0(1) P-C(av)
115.3 (5) 180.3
Q
Figure 1. S~~ hawing of 6. Ellipsoids are scaled to represent the 50% probability surface.
complex, the C-C distances would have been expected to show greater alternation.' Similar to ring slippage in ordinary Cp complexes, that in 3 is reversible leading to new heterobimetallic fulvalenes.2d,s (7) Compare to the structures of 14- and $-fulvene complexes: Edelman, F.; Lubke, B.; Behrens, M. Chem. Ber. 1982,115,1325; 1984, 117, 3463. Dauter, Z.; Hansen, L. K.; Mawby, R. J.; Probitts, E. J.; Reynolds, C. D. Acta Crystallogr., Sect. C: Cryst. Struct. Conmun. 1985, C41, 850 and references therein.
C(l)-C(6) C(l)-C(2) C(l)-C(5) C(2)-C(3) C(4)-C(5) C(3)-C(4)
142.7 (5) 142.7 (6) 143.3 (6) 141.3 (8) 142.0 (7) 138.0 (8)
C(6)-C(7) C(6)-C(lO)
142.0 (5) 141.4 (6)
C(7)-C(8) C(9)-C(lO) C(8)-C(9)
135.8 (7) 138.1 (7) 139.1 (7)
Reaction of 3 with PMe, (2-3 equiv, -0.1 M, 120 " C ) or PEt, (5 equiv, -0.2 M, 120 "C) gave moderate yields of 4 (44%) and 5 (58%),re~pectively.~ Their room-temperature 'H NMR spectra exhibit only four multiplets in the Fv region instead of the expected eight, suggesting fluxional behavior. Indeed, a t -78 "C significant broadening of the three lowest field Peaks and the splitting of the fourth into two multiplets was observed. A possible explanation for this finding might be the exchange of two carbonyl ligands between the two metals via pairwise shifts between terminal and bridged bonding modesg (Scheme II), observed for cyclopentadienylmetal (8) Huffman, M. A.; Newman, D. A.; Tilset, M.; Tolman, W. B.; Vollhardt, K. P. C., to be submitted for publication.
584
Organometallics 1986, 5 , 584-585
carbonyl d i m e r ~ . ~An J ~ important consequence of this mechanism is that only two of the carbonyls ( x and y, Scheme 11) exchange between the two metals while the third ( 2 ) remains terminally bound in a position "trans" to the phosphine. Thus, in the 13CNMR spectrum, carbonyl x and y should give rise to a singlet and a doublet tJcp) a t the low-temperature limit and to a doublet ( J '/JrP) a t high temperature, while carbonyl z should remain a singlet throughout. confirmation of these predictions was accomplished by acquisition of variable-temperature (-75 "C to +55 "C) 13C NMR data for I3CO-labeled 5." Line-shape analysis'2 of the four spin system, assuming exchange between only two spins as dictated by the proposed mechanism, allowed calculation of the activation parameters for the fluxional process: AGtZg8= +12.0 (1)kcal mol-l, AH* = +8.8 (2) kcal mol-', and AS* = -10.6 (1.0) eu. A bridging dicarbonyl intermediate or transition state of the type depicted in Scheme I1 has never been observed in any of the other known carbonyl FvM, complexes, unlike the situation encountered in the CP,M,(CO)~ (M = Fe, Ru) dimers where it is thermodynamically stable.Ioa
Acknowledgment. This work was supported by the Director, Office of Energy Research, Office of Basic Energy Sciences, Chemical Sciences Division of the U S . Department of Energy, under Contract DE-AC03-76SF00098. W.B.T. is the recipient of a W. R. Grace Fellowship (1984-1985) and K.P.C.V. is a Miller Research Professor in Residence (1985-1986). Support from Nicolet Instruments, Madison, WI, is gratefully acknowledged by R.B. as well as the assistance of D. Blaser (University of Essen). Supplementary Material Available: Listings of positional and thermal parameters, bond lengths and angles, and structure factors of 6, variable-temperature 13CNMR spectra of 13CO-labeled 5 , and melting point, spectral, and analytical data on 4-6 and 8 (48 pages). Ordering information is given on any current masthead Page. (9) Adams, R. D.; Cotton, F. A. J . Am. Chem. Soc. 1973, 95,6589. (10) (a) Gansow, 0. A,; Burke, A. R.; Vernon, W. D. J. Am. Chem. Soc. 1976,98,5817. (b) Haines, R. J.; DuPreez, A. L. Inorg. Chem. 1969,8, 1459. Adams, R. D.; Brice, M.; Cotton, F. A. J . Am. Chem. SOC.1973,95, 6594. Kirchner, R. M.; Marks, T. J.; Kristoff, J. S.; Ibers, J. A. Ibid. 1973, 95,6602. Howell, J. A. S.; Rowan, A. J. J . Chem. Soc., Dalton Trans. 1980,1845. (11) 'jCO-labeled 5 was prepared via the reaction of PEt, with ':'COlabeled 3,which was in turn synthesized from the reaction of I3CO with 3 (50 psi of I3CO, 130 "C, THF, 50 h, approximately 20% incorporation by IR and I3C NMR). (12) Line-shape analysis was performed at the UCB Computer Center using DYXAMAR, a modified version of a program developed by: Meakin, P.; Muetterties, E. L.; Tebbe, F. N.; Jesson, J. P. J . Am. Chem. SOC.1971, 93,4701. Jesson, J. P.; Meakin, P. Acc. Chem. Res. 1973,6.269. Data were plotted according to the Eyring equation In (nhk/khT)= -AH*/RT + S * / R and fitted to a straight line using linear least-squares program ACTPAR: a modified version of a program developed by: Binsch, G.; Kessler. H. Angeu. Chem.. Int. Ed. Engl. 1980, 19, 411.
Reaction of a p-Ethenylidene Diiron Complex with Ethyl Dlazoacetate Charles P. Casey' and Edwln A. Austin Department of Chemistry, University of Wisconsin Madison, Wisconsin 53706 Received October 8, 1985
Summary: The g-ethenylidene complex [(C,H,)(CO)Fe] 2(p-C=CH2)(2) reacted with ethyl diazoacetate in the presence of CUI to produce the cyclopropylidene com0276-7333/S6/2305-0504$01.50/0
plex [(C,H,)(CO)Fe] ,(p-CO)(p-CCH2CHC02Et) (3). Cyclopropylidene complex 3 underwent acid-catalyzed ring opening to give palkenylidene compound [(C,H,)(CO)(5). Photolysis of 2 and ethyl Fe] ,(pC=CHCH,CO,Et) diazoacetate gave the allene complex [(C,H,)(CO)Fe] 2(/L-CH,=C=CHCO~E~) (6).
For the past several years, we have been studying new carbon-carbon bond-forming reaction of diiron complexes with bridging hydrocarbon ligands. We discovered the addition of the C-H bond of the cationic bridging methylidyne complex [ (C,H,)(CO)Fe],(p-CO)(p-CH)+ (1) across the carbon-carbon double bond of alkenes which produces new p-alkylidyne complexes.lJ We have also found that neutral p-alkenylidene complexes (in equilibrium with cationic p-alkylidyne complexes) condense with aldehydes under acidic conditions to produce vinylcarbyne diiron complexes.3 Hoel's recent report* of the coppercatalyzed cyclopropanation of the p-ethenylidene complex (CjH5)2(CO)zFe,(p-CO)(p-C=CH2) (2) with diazomethane sparked our interest in the reactions of diazoesters with p-alkenylidene complexes. Here we report three different selective reaction pathways for the reaction of p-ethenylidene complex 2 with ethyl diazoacetate that lead to bridging cyclopropylidene, alkenylidene, and allene complexes. Ethenylidene complex 2 reacts with ethyl diazoacetate only in the presence of a copper catalyst or upon photolysis. Ethenylidene complex 2 (250 mg, 0.71 mmol), excess ethyl diazoacetate (2.8 mmol), and CUI (1.3 mmol) were heated in 50 mL of refluxing CH2C1, for 19 h. After filtration and evaporation of solvent the oily residue was crystallized from hexane-CH2C1, to give a single isomer of the cyclopropylidene complex 3 (185 mg, 60%).5 In the 'H NMR of 3, the ABC pattern of the cyclopropane hydrogens (Jcis = 8.0 Hz, Jtrans = 4.5 Hz, J,,, = -8.5 Hz) helped to establish the structure of 3. In the IR spectrum
(1)Casey, C. P.; Fagan, P. J. J . Am. Chem SOC.1982,104, 4950. ( 2 ) Casey, C. P.; Fagan, P. J.; Miles, W. H.; Marder. S. R. J . Mol. Catal. 1983, 21, 173. (3) Casey, C. P.; Konings, M. S.; Palermo, R. E.; Colborn, R. E. J . Am. Chem. Soc. 1985, 107, 5296. (4) Hoel, E. L.; Ansell, G. B.; Leta, S. Organometallics 1984,3,1633. (5)3,major isomer: 'H NMR (acetone-d,, 270 MHz) 6 4.84 (s, CsH,), 4.80 (s, C,H,), 4.05 (dq, J = 11.0, 7.2 Hz, OCHHCH3), 3.94 (dq, J = 11.0, 7.2 Hz, OCHHCHJ, 2.67 (dd, J = 8.0, 4.5 Hz, CHCO,Et), 2.56 (dd, J = -8.5, 8.0 Hz, CHHCHC02Et), 2.53 (dd, J = -8.5, 4.5 Hz, CHHCO,Et), 1.13 (t, J = 7.2 Hz, CHJ. I3C NMR (acetone-d,, 0.07 M Cr(acac),, 50.1 MHz) 6 269.9 (w-CO),213.0 (CO), 212.3 (CO), 175.2 (CO*), 155.9 (w-C), 89.8 (d, J = 183 Hz, C5H5),89.5 (d, J = 180 Hz, C5H5),5.97 (t, J = 148 Hz, CH2CH3),34.0 (t, J = 165 Hz, CCH,CH), 32.7 (d, J = I70 Hz, CHCO,Et), 14.3 (4, J = 125 Hz, CH,); IR (CH2C1,) 1999 (4, 1957 (m), 1788 (m), 1704 (m) cm-'; HRMS calcd for C,9Hl,Fe20j 437.9847, found 437.9852. 4, minor isomer: 'H NMR (acetone-d,, 270 MHz) 6 4.75 (s, C5HJ, 4.70 (s, C5H5),4.14 (m, OCH2),2.95 (dd, J = 8.5, 4.9 Hz, 1 H), 2.48 (dd, J = 8.5, 4.9 Hz, 1 H), 2.37 (t, J = 8.5 Hz, 1 H), 1.20 (t, J = 6.8 Hz, CH,)
0 1986 American Chemical Society
