3817
Organometallics 1995, 14, 3817-3826
Cyclopentadienylcobalt Coordination to Alkenylarenes: From 1,3-DieneCoordination to p-Arene Cluster Complexes Hubert Wadepohl,” Till Borchert, Klaus Buchner, Michael Herrmann, Franz-Josef Paffen, and Hans Pritzkow Anorganisch-Chemisches Institut der Ruprecht-Karls-Universitat, I m Neuenheimer Feld 270, 0-69120 Heidelberg, Germany Received February 27, 1995@ Reaction of [CpCo(CzH4)21, 7,with a number of alkenylnaphthalene derivatives C ~ O H ~ R
(R= l-CH=CHz, 2-CH=CHz, 1-CH=CHMe, and l-CH=CHPh) gave the mononuclear [CpCo{ q4-(alkenyl)naphthalene}l complexes 15a,b, 16,and 17. In these complexes, two n-electrons each of the naphthalene nucleus and the olefinic side chain are involved in metal coordination. The crystal and molecular structure of the 1-vinyl derivative, 15a, has been determined. Relevant crystal parameters are as follows: orthorhombic, space group Pcab; 2 = 8; a = 8.206(1) b = 11.372(3) c = 28.067(7) wR2 = 0.131 (based on 2308 unique reflections), R = 0.050 (1374 reflections with I L 2dI)). The distribution of carbon-carbon bond lengths indicates considerable electronic localization within the metal-coordinated part of the sixmembered ring. Strong metal-to-ligand bonding is shown by equilibration of the carboncarbon bonds within the 1,3-diene system. From m- and p-distyrylbenzene and 7 the were obtained. Here, coordination dinuclear complexes [(CpCo)~(q4:q4-distyrylbenzene)l18a,b to each metal is in a 1,3-diene fashion via an olefinic double bond and a localized double bond of the central arene (phenylene) ring. In toluene, 18b partially decomposed to form [(CpCo)3(~3-q~:q~:q~-p-distyrylbenzene)l, 19. Both 18b and 19 were also formed from p-distyrylbenzene and [CpCo(C&Ie6)], 8. Compound 19 is fluxional in solution; the barrier AG* for arene rotation was estimated to 50 kJ mol-l a t 250 K. From the reaction of a-methylstyrene, CpzCo, and potassium, a minor amount of [CpCo{1-3,8,9-q-(l-Cp-3-Me1-cobaltaindenyl)}] 20 was isolated. Compound 20 has been characterised by X-ray crystallography. Crystal data: tetragonal, space group I & 2 = 8; a = 18.150(12) c = 9.307(5) wR2 = 0.100 (based on 1878 unique reflections), R = 0.045 (1373 reflections with I L 20(I)).
A,
A,
A;
A,
A;
Introduction The close similarity of the isoelectronic “conical” fragments (C0)3(dn-M)and Cp(d”+l-M)is well-known. On the basis of a simple frontier orbital treatment, the now very common term isolobal was coined t o describe the relationship of such fragments and t o understand its chemical consequences.’ Particularly widespread are complexes 1 and 2 of the isolobal and isoelectronic fragments (C0)3Fe and CpCo with open-chain or cyclic conjugated dienes. Although in many cases 1 and 2 show quite similar structures and chemical reactivity, important differences do exist.
co
1
Fe
2
When styrene derivatives are treated with sources of (C013Fe (e.g., [Fe(C0)51,2[(C0)3Fe(cyclooctene~~13~, the @Abstractpublished in Advance ACS Abstracts, July 1, 1995. (1)Elian, M.; Chen, M. M. L; Mingos, D. M. P; Hoffmann, R. Inorg. Chem. 1976 15, 1148.
iron becomes attached to the diene system formed by the vinyl group and one of the carbon-carbon bonds of the arene nucleus (Scheme 1). Structural4 and spectroscopic2 data as well as chemical reactivity2 consistently indicate a loss of aromatic character of the coordinated arene in 4. In many cases, 4 takes up a second (C0)3Fefragment, and the dinuclear complex 5 is formed.2 As shown by the crystal structure analysis of the m,a-dimethylstyrene deri~ative,~ the two metals in 5 adopt the anti arrangement, one on each face of the styrene ligand. In marked contrast, trinuclear cluster complexes 6 with face-capping arene ligands are formed when ring or side-chain-substitutedstyrenes are treated with reactive sources of the CpCo moiety (e.g., [CpCo(C2HdzI,7, and [CpCO(CsMedl,W.‘ We have proposed a mechanism for this ligand assisted assemblage of the trinuclear metal cluster (Scheme 2X7 As one of the first steps the formation of (2) (a)Rae Victor; Ben-Shoshan, R.; Sarel, S. Tetrahedron Lett. 1970, 49, 4253, 4257. (b) Rae Victor; Ben-Shoshan, R.; Sarel, S. J . Chem. SOC.,Chem. Commun. 1970, 1680. ( c ) Rae Victor; Ben-Shoshan, R.; Sarel, S. J . Org. Chem. 1972,37,1930. (3) Fleckner, H.; Grevels, F.-W.;Hess, D. J.Am. Chem. Soc. 1984, 106, 2027. (4)(a) Herrmann, W. A,; Weichmann, J.; Balbach, B., Ziegler, M. L. J . Organomet. Chem. 1982,231,C69. (b)Adrianov, V. G.; Struchkov, Yu. T.; Babakhina, G. M.; Kritskaya, I. I.; Kravtsov, D. N. Izu. Akad. Nauk SSSR, Ser. Khim. 1985,590. (5) Herbstein, F. H.; Reisner, M. G. Acta CrystalEogr. 1977,1333,
3304.
0276-733319512314-3ai7~ag.aaia 0 1995 American Chemical Society
Wadepohl et al.
3818 Organometallics, Vol. 14, No. 8, 1995
Scheme 2
-
R
7or8
Scheme 3
I
7
R2
13
a mononuclear “diene” complex 9 with a P,a,l,2-q4coordinated alkenylbenzene ligand was proposed. However, examples of such complexes with simple styrenes as ligands are conspicuously absent from the literature. We ourselves were unable to detect them during the one-pot syntheses of 6. Likewise, in such cases where a p-arene cluster complex did not form with a particular substituted styrene ligand, neither 9 nor other monoor dinuclear CpCo complexes were found. From these results it seemed obvious that the mononuclear cobalt complexes 9 should be considerably less stable and more reactive than their iron analogs 4. On the other hand, a few compounds have been reported with this type of coordination as a part of a more complicated oligonuclear structure, e.g., [(CpxCo)3(1,6,1’,6’-q:2-5-q:2’-5’-q4-biphenyl)l*and [(CpCo)a(2,3,8,9-7:4-7-q- 4,5,6,7-(CF&indene)3.9 Thus it did not seem impossible to stabilize more simple CpCo derivatives. In this paper we present our studies of the ligand properties of alkenylnaphthalenes and distyrylbenzenes toward the CpCo moiety. These ligands were chosen because in each case a different kind of stabilization of the “diene” complex was anticipated: (a) Compared t o a monocyclic system, less resonance energy is lost when part of the extended n-system of a bicyclic arene coordinates to a metal. Furthermore, the more polyene-like nature of the condensed aromatic rings is expected to facilitate attack by a metal frag(6)(a)Wadepohl, H.; Buchner, K.; Pritzkow, H. Angew. Chem. 1987, 99, 1294.(b) Wadepohl, H.; Buchner, K.; Herrmann, M.; Pritzkow, H. Organometallics 1991,10,861. (c)Wadepohl, H.Angew. Chem. 1992, 104, 253.
(7)Wadepohl, H.; Buchner, K.; Pritzkow, H. Organometallics 1989, 8, 2145.
( 8 ) Lehmkuhl,
H.;Nehl, H.; Benn, R.; Mynott, R. Angew. Chem.
1986,98,628. (9) Freeman, M.B.; Hall, L. W.; Sneddon, L. G. Inorg. Chem. 1980,
19,1132.
c;,I
e
14
ment. This has been known to work in (C0)3Fe chemistry (complex 11l0 1. Some of our results have been mentioned in an earlier comm~nication.~
(b) As an alternative, we hoped to trap 9 as a dinuclear complex, which, unlike the proposed intermediate 10,would not easily proceed to the trinuclear 6. Such a possibility exists with dialkenylbenzene ligands (Scheme 3). Addition of another CpCo fragment to the primary product 13 is expected to involve the free alkenyl group. Most of the resonance energy of the arene is lost in the first step, therefore formation of the dinuclear 14 from 13 should be more facile. In (C013Fe chemistry, introduction of a second vinyl group to styrene is already known t o strongly enhance the tendency to form the bis(P,a,1,2-q4) complex 12.l’ In addition, since the cobalt atoms are well separated from each other in 14, this product was not expected to be on the reaction coordinate leading to a p3-arene complex.
Results Cyclopentadienylcobalt Complexes of AlkenylSubstituted Naphthalenes. (a) Syntheses and Spectra. When 1-or 2-vinylnaphthalene was gently heated with approximately equimolar amounts of [CpCo(10)Manuel, T. A.Inorg. Chem. 1964,3, 1794. (11)(a)Manuel, T. A,; Stafford, S. L.; Stone, F. G. A. J . A m . Chem. SOC.1961,83,3597.(b) Davis, R.E.; Pettit, R. J . Am. C h e n . SOC.1970, 92,716.
CpCo Coordination to Alkenylarenes
Organometallics, Vol. 14,No. 8, 1995 3819
(C2H4)21,7, greenish-brown solutions were obtained. The 1-vinylnaphthalene complex 15a was obtained as dark
..
.. co
co
150, R = H 16, R = Me 17. R = Ph
15b
green crystals after cooling the reaction mixture. The 2-vinylnaphthalene complex 15b crystalized much less readily and had to be separated from the by-products by column chromatography on deactivated alumina. [CpCo(l-propenylnaphthalene)]16 was obtained in a similar manner. However, due to slow decomposition on the chromatography column, it proved to be impossible to completely separate 16 from traces of 1-(propen1-y1)naphthalene. In a mononuclear CpCo complex with l-(P-styryl)naphthalene as a ligand, the metal could be attached to the acyclic carbon-carbon double bond and part of either the naphthalenyl or the phenyl x-system. Only a single product, 17, however, was formed from this ligand and 7. Unfortunately, as in the case of 16, slow decomposition during chromatography prevented the isolation of pure 17, which was always contaminated with variable amounts of the free ligand. The structures of the complexes 15-17 were established by NMR spectroscopic means and, in the case of Ea, by single-crystal X-ray structure analysis. lH NMR spectroscopic data are given in Tables 1 and 2. The spectrum of 15a was completely assigned by a series of lH-lH-decoupling experiments, those of 15b17 by analogy. The metal coordination of the vinyl group reveals itself by a strong high-field shift of the two methylene proton resonances. These show a considerable chemical shift difference, H-Pendoresonating at much higher field than H-Pexo.The ‘H NMR spectra of 16 and 17 (Table 2) also present no difficulties. From the magnitude of the coupling constants 3J(H-a-H-P) a trans configuration of the alkenyl double bonds can be assumed, as expected for steric reasons. In all cases, the proton on the metal coordinated carbon-carbon bond of the naphthalene ring (H-2 in 15a, 16, and 17; H-1 in 15b) resonates at high field. This is characteristic of an “outer” proton in a v4-1,3-dienecomplex and indicates loss of aromatic character. The usual (high field) coordination shifts are also observed in the 13C NMR spectra. (b) Crystal and Molecular Structure of [CpCo(B,a,1,2-q-(l-vinyl)naphthalene)I, 15a. Single crystals of 15a were obtained when the reaction mixture was slowly cooled to room temperature. Crystal details are given in the experimental section. The molecular structure of 15a is shown in Figure 1. Positional and equivalent isotropic displacement parameters are given in Table 3; important bond lengths and angles are given in Table 4. The crystal structure of 15a consists of discrete molecules with no unusual intermolecular contacts. The vinyl group (C11, C12) and the carbon atoms C1 and C2 of the vinylnaphthalene ligand are bonded in a 17*-
1,3-diene fashion to the cyclopentadienylcobalt fragment. Carbon-carbon bond lengths within the “diene” system are approximately equal. The substituents a t the outer “diene” carbon atoms (C3, H2 and H12A, H12B) do not occupy positions in the plane defined by the “diene”system. The distortion is such that the endo substituents are moved away from and the ex0 substituents are moved toward the cobalt atom. The cyclopentadienyl ring is approximately parallel t o the “diene” plane, which is bent away from the naphthalene backbone (interplanar angle, 15.3(3)”). There is considerable bond localization in the metalcoordinated six-membered ring of the naphthalene bicycle as indicated by the short (doub1e)bond C3-C4 (1.32(1) A). The two fused six-membered rings of the vinylnaphthalene ligand are both essentially planar, with a dihedral angle of 4.2(3)O between the planes. Cyclopentadienylcobalt Complexes of m- and p-Distyrylbenzene. Reaction of m-distyrylbenzene with excess (2-3 mol equiv) of 7 at 40 “C gave the redbrown dinuclear complex 18a in about 65% yield. Complex 18a is quite labile and decomposed on attempted chromatography.
9 I
180
9 I
___
co /\
0
“1“
0 18b
The reaction of 7 with p-distyrylbenzene is much impeded by the very low solubility of this ligand in practically any solvent. When suspended in a solution of excess 7 in petroleum ether, the p-distyrylbenzene slowly dissolved and the color of the solution changed from orange to brown. From this mixture a 65%yield of the dinuclear 18b was isolated by chromatography. During an attempt to recrystallize 18b from toluene most of the complex decomposed predominantly to a new complex, 19. The ’H NMR spectrum of the mixture
e3 19
indicated that 19 was a (Cpco)~ cluster complex with a
Wadepohl et al.
3820 Organometallics, Vol. 14, No. 8, 1995
-
Table 1. ‘HN M R Spectral Data (200 m z , in C&) for the [CpCo(+Vinylnaphthalene)] Complexes, 15a and 15b 15b
15a
mult J(HHY int
d
H-1 H-Pendo -0.38 H-2 1.56 H-Pexa 1.91 CP 4.16 H-a 6.11 H-3 6.78 H-4 6.93 arene-H 7.35-8.27 (I
d
2.33 8.6 5.2 5.2
mult J(HHF int S
1 -0.41 1 1 1.79
dd
S
5
S
m m m m
1 1 1 b
d d d
4.12 5.48 6.92 7.42 7.00-7.64
1
9.4h.8 1
c
5
dd 9.2/6.7 1 d 9.1 1 d 9.1 1 m b
In Hz. Overlap with solvent signal.
16
d
H-Penda H-2
0.3 1.47 Cp 4.10 H-a 5.86 H-3 6.78 H-4 6.9 arene-H 7.1-8.3 1.13 a
x
dd 6.6h.8 1
Table 2. ‘HNMR Spectral Data (200 MHz, in C&S) for the [CpCo(q4-(l-CH=CHR)naphthalene)l Complexes, 16 (R = CHd and 17 (R= Ph)
R
27
17
mult AHHP int 6 mult J(HHP int 8.8 1 d m 1 1.09 d 5.6 1 “d” 1 1.85 5 S S 5 3.93 8.8 1 d “d” 1 6.62 1 m m 1 6.80 “d” 1 m 1 6.96 b m b 7.14-7.20 m 7.6 1 d 8.34 5 m d 5.1 3 7.3-7.45
In Hz. * Overlap with solvent signal.
face-cappingp-distyrylbenzene ligand. However, other decomposition products could not be completely removed from this sample. The reaction was therefore repeated with [CpCo(CsMedl 8 as a source of CpCo fragments. A mixture of 18b and 19 was obtained, which could be separated by column chromatography into two fractions, consisting of pure 18b (28% yield) and pure 19 (25% yield), respectively. The structures 18a,b are assigned to the dinuclear products on the basis of lH (Table 5 ) and 13C NMR data. The coordination of two CpCo fragments to the ligand in each case is immediately evident from the integrals and, in the case of lSb, from the high symmetry of the spectra. The spectra also show unambiguously that each CpCo group simultaneously bonds to an acyclic carboncarbon double bond and t o a part of the central arene ring of the ligands. As in 15-17, the “outer” diene protons (H-p,p’ and H-2,4 in 18a; H-P,p’ and H-2,3in 18b) are easily identified by their high field shifts (Table 5). The trans configuration of the C-a-C-P bonds is revealed by the large coupling constants 3J(H-a-H-/3). The 13C NMR resonances of the metal coordinated carbon atoms are also shifted to high field, again with d(Couter) < d(Cinner). The lH NMR spectrum of 19 (Table 6) is typical of a (CpCo)s cluster bearing a face-capping arene ligand. Again, the symmetry of the spectra is only compatible with the cluster coordination of the central arene (phenylene)ring of the p-distyrylbenzeneligand. Chemical shifts (WH) and d(13C),Table 7) and the coupling constant 3J(H-a-H-p) exclude participation of the C-aC-p double bonds in the coordination to the metals. Once again, trans configuration of these bonds is implied by the magnitude of 3J(H-a-H-p). When the solution is cooled, the Cp singlet resonance
Figure 1. Molecular structure of [CpCo(/3,a,l,2-( 1-vinyl)naphthalene)], 15a, showing the crystallographiclabeling scheme. Table 3. Atomic Coordinates (A x 104) and Equivalent Isotropic Displacement Parameters ( A 2 x 10s) for 1Saa atom
Y
X
2
uwa
CO(l) C(1) C(2)
1928(1) 223(1) 786(1) 72(1) 291(5) 1295(3) 1083(2) 7U1) -611(6) 388(4) 846(2) 91(2) -1457(7) -445(5) 1135(3) 116(2) C(4) c(3) -1487(6) -382(5) 1605(3) 118(2) C(5) -812(7) 680(6) 2356(3) 108(2) C(6) -135(7) 1616(7) 2586(2) 111(2) C(7) 653(6) 2470(5) 2334(2) 97(2) C(8) 79x51 2383(4) 1848(2) 77(1) C(9) 135(4) 1432(3) 1601(2) 65(U C(10) -711(5) 563(4) 1859(2) 84(1) C(11) 1449(7) 1916(4) 801(2) 90(2) C(12) 1694(14) 1568(6) 319(2) 120(2) C(13) 2597(5) -1138(3) 1230(1) 84(1) -1546(3) 770(2) 98(2) C(14) 2309(5) C(15) 3384(6) -973(4) 464(1) 108(2) C(16) 4336(5) -212(4) 735(2) 111(2) (317) 3850(5) -314(4) 1209(2) 99(2) U,, is defined as one-third of the trace of the orthogonalized Ujj tensor. [I
Table 4. Selected Bond Lengths (A)and Angles (deg) for 15a with Estimated Standard Deviations in Parentheses Co(1)-C(1) Co(l)-C(ll) Co(l)-C(13>*C(17) C(l)-C(9) C(2)-C(3) C(4)-C(lO) C(5)-C(10) C(7)-C(8) C(9)-C(lO) C(ll)-C(l)-C(2) C(2)-C(l)-C(9) C(4)-C(3)-C(2) C(6)-C(5)-C(lO) C(6)-C(7)-C(8) C(8)-C(9)-C(lO) C(lO)-C(9)-C(l) C(g)-C(lO)-C(4) C(l2)-C(ll)-C(l)
1.999(5) Co(l)-C(2) Co(l)-C(12) 1.964(5) 2.025(4>.*2.066(4) C(l)-C(2) C(l)-C(ll) 1.466(7) C(3)-C(4) 1.422(9) C(5)-C(6) 1.438(9) C(6)-C(7) 1.407(8) C(8)-C(9) 1.372(7) C(ll)-C(12) 1.409(6) 116.3(5) 119.4(5) 122.8(6) 121.5(6) 120.3(6) 118.7(5) 118.5(4) 119.3(6) 119.2(7)
C(ll)-C(l)-C(9) C(3)-C(2)-C(1) C(3)-C(4)-C(lO) C(5)-C(6)-C(7) C(7)-C(8)-C(9) C(8)-C(9)-C(l) C(9)-C(lO)-C(5) C(5)-C(lO)-C(4)
2.103(6) 2.025(7) 1.436(6) 1.426(7) 1.324(10) 1.361(9) 1.363(8) 1.395(6) 1.427(9) 123.8(4) 117.7(5) 121.7(6) 120.2(6) 121.2(5) 122.8(4) 118.1(5) 122.6(6)
in the lH and 13CNMR spectra broadens and then splits into two components of unequal intensity (Figure 2). Likewise, two 13C resonances are observed a t 210 K for the four CH carbons of the p3-phenylene ring (Table 7). Unfortunately, the lH NMR resonances of the p3-
CpCo Coordination to Alkenylarenes
Organometallics, Vol. 14,No. 8, 1995 3821
Table 5. lH NMR Spectral Data (200 MHz, in C&) for the [(CpC0)2(q~:~~-distyrylbenzene)] Complexes, 18a and 18b.
H-a 5.66 H-a' 5.89 H-P 1.01 H-P 1.34 H-2 2.58 H-3 H-4 1.38 H-5 6.35 H-6 6.89 Cp 4.16, 4.22 Ph 7.07-7.42
mult d d d d
JHHP 8.8 8.8 8.8 8.9
S
int
d
1 5.60 1 1 0.95 1 1 1.92
1.92 d dd d S S
m
293 K
18b
18a d
Table 7. lsC('H) NMR Spectral Data (50.3 MHz, in CD2Ch) for the [(CpC0)3013-1~:9~:9~'p' distm1benzene)l Complex, 19.
5.4 1 9.015.4 1 6.86 9.2 1 6.86 5 4.13 5 c 7.05-7.39
mult J(HHP int d 9.0 2 d
8.8
S
S
S
b b 10
m
c
S
S
parene
40.8
CP
56.1 83.5
C CH
121.0 125.7 126.2 129.1 138.9 138.9
CH CH CH CH C CH
2 b b
210 K multa CH
d
C-B Ph
C-a a
d
40.8 44.0 58.5 82.6 82.8 119.5 124.8 125.9 128.5 137.7 137.0
multa CH CH C CH CH CH CH CH CH C CH
Determined by DEPT spectra.
In Hz. Only one signal of intensity 2 for the two isochronous protons. Overlap with solvent signal. a
Table 6. 'H NMR Spectral Data (200 MHz, in CD2C12) for the [ ( C P C O ) S ( ~ ~ S - ~ ~ : ~ ~ : ? ~ - ~ dist~ry1benzene)lComplex, 19 293 K 230 K mult J(HH)" int d mult AHHP 14-arene 4.87 s 4 4.79 CP 4.92 s 15 4.79 "s" 5.07 s alkene 6.54 c 16.1 2 6.45 c 16.1 6.72 c 16.1 2 6.70 c 16.1 Ph 7.28 m 10 7.26 m d
[I
int b b 5 2 2 10
1
In Hz. * Overlapping peaks, total intensity 14. AB system.
phenylene ring overlap with one of the two Cp resonances a t low temperature. Other areas of the spectra are essentially independent of temperature. Reaction of a-Methylstyrene with CpzCoIPotassium. When an excess of a-methylstyrene is treated with 7, the cluster complex [(CpC0)3cu3-)7~:11~:~~-amethylstyrene)] is formed in good yield.7 However, when CpCo fragments were generated via reductive degradation of cobaltocene with potassium12 in the presence of a-methylstyrene, mainly organic decomposition products were obtained. After careful chromatography of the reaction mixture, a minor organometallic product was isolated in very low yield. Structure 20 was assigned to this product on the basis of spectroscopic data and a single-crystal X-ray diffraction study (vide infra).
-
Me 7.5 I
Q5 "/c o 20
In the lH and 13CNMR spectra there are two distinct resonances for the two chemically inequivalent CpCo
groups. Unfortunately, not all of the resonances required for the benzocobaltole bicycle (five CH and three C) were detected in the carbon spectrum. This could be due to effects of the quadrupolar 59C0nucleus of the endocyclic CpCo group on the two carbon atoms (one C and one CH) which are a-bonded to it. Similar observa(12) Jonas, K., Kruger, C. Angew. Chem. 1980, 92,513.
7.0
6.5
6.0
5.5
5.0
4.5
Figure 2. Temperature dependent 200 MHz 'H NMR spectra of complex 19. Temperatures are at (top to bottom) 297,280,275,270,265,260,255,250,240,and 220 K. The signal at 6 5.3 is due to solvent protons. tions were made in complexes containing a cobaltapentalene bicyclic ring system.13 Crystal and Molecular Structure of Cobalt Dimer 20. Deep green single crystals of 20 were obtained from n-hexane a t -78 "C. Crystal details are given in the Experimental Section. The molecular structure of 20 is shown in Figure 3. Positional and equivalent isotropic displacement parameters are given in Table 8; ~~~
~
(13)Wadepohl, H.; Galm, W.; Pritzkow, H.; Wolf, A. Angew. Chem. 1992, 104,1050.
3822 Organometallics, Vol. 14, No. 8, 1995 n
Figure 3. Molecular structure of [CpCo(l-3,8,9-y-(l-Cp3-Me-l-cobaltaindenyl))], 20, showing the crystallographic labeling scheme. Table 8. Atomic Coordinates (A x lo4) and Equivalent Isotropic Displacement Parameters < A 2 x 103) for 200 atom
X
Y
z
7742(1) 9933(1) 9329(9) 10684(9) 10576(9) 9165(9) 8980(13) 10084(19) 11471(16) 11766(12) 12080(9) 5854(10) 5966(10) 6008(9) 593U 10) 5847(10) 10600(12) 9252(11) 9393(11) 10833(13) 1155511)
U,, is defined as one-third of the trace of the orthogonalized
U, tensor.
Table 9. Selected Bond Lengths (A)and Angles (deg) for 20a with Estimated Standard Deviations in Parentheses
important bond lengths and angles are given in Table 9. The crystal structure of 20 consists of discrete molecules with no unusual intermolecular contacts. Com-
Wadepohl et al. plex 20 is best described as a cyclopentadienylcobalt complex of a y5-benzocobaltole(or cobaltaindenyl) ligand. The individual cobaltole and benzo rings are essentially planar (root mean square deviation from the best planes, 0.018 and 0.015 A, respectively). The complete benzocobaltole is only slightly (1.9(3)”)folded along C3C4. The noncoordinated part of the six-membered ring can be thought of as a diene unit (C5 to C8) with two short and one longer carbon-carbon bonds joined to the rest of the molecule by two longer (mean 1.44 A) such bonds. Within the cobaltole ring carbon-carbon bonds are of approximately equal length. The planes of the cobaltole and Cp rings are at angles of 3.3(3) [Cp(Co2)1 and 77.1(3)”[Cp(Col)l, respectively. Reaction of Alkenylnaphthalene Complexes 15a and 17 with 7. The 1-vinyl- and 1-styrylnaphthalene complexes 15a and 17 were treated with 1 additional equiv of 7 for several hours at room temperature. lH NMR inspection of the mixtures indicated that no reaction had taken place. The mixtures were then heated to 45-60 “C for another 2-6 h. After workup, some of the starting 15a and 17 was recovered, along with the ethylidyne hydrido cluster complex [H(CpCo)4(CMeIl, the thermal decomposition product of 7.14
Discussion
CpCo(/3,a,1,2-r,r-Alkenylnaphthalene) Complexes 15-17. The reactivity of CpCo with the alkenylnaphthalenes very nicely parallels that of the (C013Fe moiety. However, the CpCo complexes 15-17 appear to be less stable than their (C013Fe analogs. Unfortunately, no di- or trinuclear alkenylnaphthalene complexes could be prepared from the mononuclear products. The molecular structure of [(CO)sFe(P,a,l,2-(1-~inyl)naphthalene)] has been reported in the literature.llb In this complex, the carbon-carbon bond lengths within the vinylnaphthalene ligand are essentially identical to the correspondingdistances in 15a. Disrupture of cyclic conjugation within the metal-coordinated six-membered ring is indicated by a pronounced alternation of carboncarbon bond lengths. The distance C3-C4 (1.32(1)A in 15a) is typical of a double bond. The other ring of the naphthalene, which is not directly coordinated to the metal, retains its aromaticity. Extensive delocalization within the metal-coordinated diene substructure is indicated by the same length of the two ((outer” and the one “inner” carbon-carbon bonds (Cl-C2, Cll-C12, and C1-C11 in 15a). This is indicative of a bonding interaction with the metal of similar strength in both the iron and the cobalt complex. The range of cobalt-carbon distances (Table 4) indicates some asymmetry in the metal-to-diene bonding. A similar pattern was found in the (C0)sFe complexes of a-methylstyrene and l,l-diphenylpr~pene.~ The substantial folding along Cl-C2 of the vinylnaphthalene ligand is related to the out-of-plane distortion concerning the substituents at the outer diene carbon atoms. Such a distortion is commonly found in complexes of acyclic y4-1,3-dienes. It was attributed to (14)(a) Gambarotta, S.; Floriani, C.; Chiesi-Villa, A,; Guastini, C. J . Organomet. Chem. 1985, 296, C6. (b) Wadepohl, H.; Pritzkow, H. Polyhedron 1989, 8, 1939.
-
CpCo Coordination to Alkenylarenes
Organometallics, Vol. 14, No. 8, 1995 3823
Scheme 4 ICpCol
-
co
I
lab
the steric interaction of the two endo substituent^.'^ Naturally, these are not present in the cobaltaindenyl ring sytem of 20, and consequently the latter ligand is essentially flat. During the reaction with a-styrylnaphthalene, the CpCo fragment has a choice between getting attached to the acyclic double bond and part of the phenyl or naphthalenyl n-system. Only coordination of the condensed arene was found. This is in accord with our expectations, on the basis of the more localized n-system of the naphthalenyl residue. Dinuclear (18a,b) and Trinuclear (19) CpCo Complexes of m- and p-Distyrylbenzene. The distyrylbenzenes were chosen as ligands because they offered a unique comparison of the reactivity of monoand disubstituted benzene rings, which are both present in the molecule. Thus attack of CpCo could be envisaged involving either the terminal phenyl or the internal phenylene rings. To some extent, the reactivity of the distyrylbenzenes with CpCo parallels that of divinylbenzene with ( C 0 ) ~ F e . l In ~ both cases dinuclear complexes are obtained. However, the observed formation of the p3arene cluster complex 19 is without precedence in iron carbonyl chemistry. It can be seen as a reflection of the better metal-metal-bonding capabilities1 of the CpCo fragment. Although, t o our knowledge, mononuclear complexes of (C0)sFe and CpCo with dialkenylbenzenes have not yet been isolated, such species are very likely formed initially. Addition of one metal fragment dramatically activates the ligand, and reaction with the second metal fragment is much faster. Therefore, the stationary concentration of a mononuclear intermediate like 21 is expected to be very low. In the present case, dissimilar results are obtained with different sources of CpCo. When 7 is used in the reaction, 21 is trapped as the dinuclear complex 18. With 8 and p-distyrylbenzene a mixture of 18a and the p3-arene cluster complex 19 is obtained. Without detailed knowledge of the mechanism of ligand exchange (15)Adams, C.; Cerioni, G.; Hafner, A,; Kalchhauser, H.; v. Phillipsborn, W.; Prewo, R.; Schwenk, A. Helv. Chim. Acta 1988,71,1116.
19
reactions of 7 and 816 we can only speculate about the different courses of reaction with p-distyrylbenzene (Scheme 4). A reasonable explanation of the experiments would be that the less reactive 7 picks coordination to the uncomplexed side chain in 21, thereby selectively forming 18. The more reactive 8 does not discriminate as well. Hence, along with 18a the arene cluster complex 19 is formed, most probably via an intermediate analogous to 10. It is interesting to note here that with stilbene (1,2-diphenylethene)as a ligand, only the cluster complex [(CpC0)3(p3-y~:r,7~:y~-stilbene)l is formed in very good yield.6b The formation of 19 when 18b is allowed t o stand in solution can be explained by dissociation of CpCo fragments from the latter. It has been suggested that these fragments are stabilized by binding to the arene ring of an aromatic s01vent.l~The very low solubility of the p-distyrylbenzene ligand, which precipitates out of the solution, could be the driving force for the stepwise dissociation of 18b. Intermediate 21 will be reformed and can then be attacked by solvated CpCo fragments to eventually give the apparently more stable pus-arene cluster complex 19. The dinuclear m-distyrylbenzene complex 18a does not transform into a p3-m-distyrylbenzene cluster complex on standing. This could be due to the much better solubility of the m-distyrylbenzene, and consequently the lesser tendency of 18a to dissociate, in accord with the above arguments. The complexes 18 have all the spectroscopic properties expected for y4-1,3-dienecomplexes. In principle, 18a,b could exist as two isomers, with the two CpCo groups in a syn or an anti arrangement with respect to the bridging phenylene ring. However, only one isomer was observed in both cases (18a and 18b). For steric reasons we believe the CpCo groups to prefer the anti arrangement, in accord with the crystallographically established structure of [((CO)3Fe)2(p-di~inylbenzene)l.l~~ The temperature dependence of the NMR spectra of 19 can be explained by a hindered rotation of the p3(16)In both cases, dissociative and associative mechanisms are feasible. (17) Barnes, C. E.; Orvis, J. A. Organometallics 1993,12, 1016.
Wadepohl et al.
3824 Organometallics, Vol. 14, No. 8, 1995
Scheme 5 R
R'
arene ligand on top of the (CpCo)3 cluster.18 This dynamic process is typical for p3-face-capping arene l i g a n d ~ . ~At J ~high temperature, rotation is fast on the NMR time scale, and hence an averaged resonance is observed in the 'H and 13C NMR spectra for the three CpCo groups. The four CH groups of the bridging phenylene ring are also averaged. When the temperature is lowered, a static p3-q2:q2:q2coordination of the ligand is attained. Disregarding rotations around single bonds and the rotational reorientation of the Cp rings around their binding axes (both of which should be very facile), the molecular symmetry corresponds to the (idealized) point group C,v. This is nicely reflected in the low-temperature spectra of 19 (Tables 6 and 7). We have been able to prove that rotation of a COSfacecapping monosubstituted arene proceeds in a series of 60" turns or 1,2-shifts of the metals around the c6 ring.6J9 In the general case (R * R , Scheme 5 ) the two possible 60°turns (clockwise,a , or counterclockwise, b ) result in a complicated exchange pathway, e.g., for the Cp resonances. Because of the higher symmetry of 19 (R = R ) , a and b are degenerate, and we are, in effect dealing with a more simple two-site exchange process. The energy barrier can be estimated from the coalescence of the Cp resonances in the 'H NMR spectrum; with the formula valid for exchange of unequally populated singlets20and T,= 250 K, we obtain AG*(250 K) = 50 k J mol-l. Ir-Complexationversus CH Activation of Alkenylbenzenes. Under certain conditions,activation of CH bonds is a general reactivity pattern of the (C5R5)Co fragments.21*22 For example, when treated with 7 or Cp&o/K, cycloolefins are dehydrogenated and incorporated as bridging cycloalkyne ligands into tri- and tetranuclear cluster complexes.23With vinylbenzenes, this kind of reactivity can be comparable to or even more facile than n-complexation of the arene and formation of a p-arene cluster complex.24 In such cases, only the products of vicinal 1,2-dehydrogenation of the vinyl group, trinuclear pa-alkyne cluster complexes, were found. The alternative geminal 1,l-dehydrogenation, possibly leading to a cluster bound vinylidene, has never yet been observed,22although in Ru3 and os3 cluster chemistry such species are of comparable stability to the p-alkyne c ~ m p l e x e s . ~ ~ (18)Or vice versa, which amounts to the same. (19)Wadepohl, H. In The Synergy Between Dynamics and Reactivity at Clusters and Surfaces; Farrugia, L. J., Ed.; NATO AS1 Series, Kluwer: Dordrecht, The Netherlands, 1995;Vol. 465,pp 175-191. (20) A 60" rotation ( aorb in Scheme 5)does not suffice to equilibrate the Cp resonances. The rate constant k' calculated with the two-site exchange formula (Shanan-Atidi, H.; Bar-Eli, K. H. J. Phys. Chem. 1970,74,961)was therefore corrected to give the actual k for processes a and b. Because of the dependence of AG* on In(k)the influence on
the former is small compared to the errors inherent in the coalescence method. (21)Wadepohl, H, Comments Inorg. Chem. 1994,15, 369. (22)Wadepohl, H; Gebert, S. Coord. Chem. Rev., in press. (23)Wadepohl, H.; Borchert, T.; Pritzkow, H. J.Chem. Soc., Chem. Commun.. in Dress. (24)Wadepohl, H.; Borchert, T.; Biichner, K.; Pritzkow, H. Chem. Ber. 1993,126,1615. ~
~
~
I----
a-Methylstyrene does not have vicinal olefinic hydrogens, therefore an alkyne complex cannot be formed. With 7 the only isolable product is the pus-arene cluster complex [(CpCo)3(~~-q~:q~:q~-a-methylstyrene)l, which is formed in good yield.6 This product is not obtained upon reaction of a-methylstyrene with Cp2Co/K, nor is a p-vinylidene cluster complex. Most of the ligand decomposes to intractable purely organic products. However, CH activation does take place to some extent, as shown by the formation of 20. This time a vinylic CH bond and an aromatic CH bond are cleaved, and a benzocobaltolemetallacycle is formed, which is further stabilized by the uptake of a second CpCo group, to give the final product 20. Complex 20 is similar to other systems with cobaltole ligands.26 A Cp Ir complex of an iridiaindenyl system was characterised by X-ray ~rystallography.~~ It shows a similar pattern of short and long carbon-carbon bonds in the metallabicycle. The geometry of these complexes points to a considerable diminution of cyclic conjugation within the benzo rings.
Conclusions We have shown in the ,present work that the q4coordination mode of an alkenylarene t o a CpCo fragment can indeed be stabilized. The coordination geometry of the "diene" unit in the P,a,l,2-q-l-vinylnaphthalene complexes of CpCo and (C013Fe is very similar. However, the mononuclear and dinuclear CpCo complexes are more labile than their (C0)3Fe analogs. Formation of trinuclear cluster complexes with the benzene nucleus of the alkenylarene in the pi-face capping coordination mode is unique to CpCo; this is well accounted for by the electronic properties of the latter fragment. Experimental Section General Procedures. All operations were carried out under a n atmosphere of purified nitrogen or argon (BASF R311 catalyst) using Schlenk techniques. Solvents were dried by conventional methods. Petroleum ether refers to the fraction with bp. 40-60 "C. The compounds [CpCo(C2H&], 7,28[CpCo(C&les)l, 8S: l - ~ i n y l n a p h t h a l e n el-propenylnaph,~~ thalene,301 - ~ t y r y l n a p h t h a l e n em , ~-~d i ~ t y r y l b e n z e n eand , ~ ~p d i ~ t y r y l b e n z e n ewere ~ ~ prepared as described in the literature. Alumina used as a stationary phase for column chromatography was first heated for several days under vacuum and then treated with 5 mass % of water and stored under nitrogen. NMR spectra were obtained on Bruker AC 200 (200.1 MHz for 'H, 50.3 MHz for 13C) and AC 300 (75.46 MHz for 13C) instruments. 'H and 13C chemical shifts are reported vs &Me4 and were determined by reference to internal SiMe4or residual solvent peaks. The multiplicities of the I3C resonances were (25)Lewis, J.; Johnson, B. F. G. Pure Appl. Chem. 1975,44,43. Deeming, A.J. Adu. Organomet. Chem. 1986,26,1. (26)( a ) Binger, P.;Martin, T. R.; Benn, R.; Rufinska, A,; Schroth, (b)Siinkel, K.J.Organomet. Chem. G. 2. Naturforsch. 1984,396,993. 1990,391,247. (27)McGhee, W. D.;Bergman, R. G. J.Am. Chem. SOC.1988,110, 4246. (28)Jonas, K.;Deffense, E.; Habermann, D. Angew. Chem. 1983, 95,729;Angew. Chem. Suppl. 1983, 1005. (29)Hashimoto, H.; Hida, M.; Miyano, S. J . Organomet. Chem. 1967, 10,518. (30)Kon, A. R.; Spickett, R. G. W. J . Chem. SOC.1949,2725. 131)Drefahl, G.;Lorenz, D.; Schnitt, G. J . Praht. Chem. 1964,23, 143. (32)Blout, E. R.;Eager, V. W. J . Am. Chem. SOC.1945,67, 1315. (33)Kauffmann, H.Ber. Dtsch. Chem. Ges. 1917,50, 515.
CpCo Coordination to Alkenylarenes determined using the DEPT or the J-modulated spin echo (JMOD) techniques; multiplicities determined by the latter method are indicated as odd (u) or even (g). Mass spectra were measured in the electron impact ionization mode (EI)a t 70 eV or using chemical ionization (negative ions, CI-, or positive ions, CI+) on Finnegan MAT 8230 and 4600 spectrometers. Elemental analyses were performed by Mikroanalytisches Labor Beller, Gottingen, Germany.
Syntheses. [CpCo(P,a,1,2-q-(l-vinyl)naphthalene)l, 15a. A solution of 1.26 g (7.0 mmol) of 7 and 0.40 g (2.6 mmol) of 1-vinylnaphthalene in 60 mL of petroleum ether was stirred a t room temperature. After 3 h, a dark grey precipitate was removed by filtration. Another 0.40 g sample of l-vinylnaphthalene was added, and the mixture was refluxed for 5 h. When the reaction mixture was slowly cooled to -20 "C, dark green crystals preciptated, which were washed two times with cold petroleum ether to afford pure 15a (0.45 g, 31%). The crystals became waxy within a few hours at roqm temperature. I3C(IH} NMR (toluene-&) 6 29.9 (C-p), 49.8 (C-2), 66.8 (C-a), 80.6 (Cp), 90.7 (C-l), 122.5 (CH), 123.5 (CH), 126.4 (CH), 127.1 (CH), 127.6 (CH), 137.7 (CH); due to slow decomposition of the sample the signals due to some of the quarternary carbons were not observed. MS (EI) mle (relative intensity) 278 (M+, 1001, 276 ([M - 2H]+, 221, 211 (101, 189 ([CpzC~l', 101, 156 (6), 154 (L+, 19), 153([L - HI+, 30), 139 (61, 124 ([CpCoI+,651, 59 (Co+, 13); L = vinylnaphthalene. [CpCo(B,u,2,1-q-(2-vinyl)naphthalene)l, 15b. A solution of 0.93 g (5.2 mmol) of 7 and 0.80 g (5.2 mmol) of 2-vinylnaphthalene in 60 mL of petroleum ether was stirred for 5 h a t room temperature. The solution was then heated to gentle reflux for another 5 h. Removal of solvent under reduced pressure led to a brown oily residue, which was redissolved in a minimal amount of petroleum ether and chromatographed on alumina using the same solvent as a mobile phase. Solvent was removed under reduced pressure from the greenish-brown first fraction t o give a brown solid. Recrystallization from petroleum ether afforded pure 15b (0.55g, 38%). 13C(IH) NMR (JMOD, CsDs) d 29.2 (u, C-p), 51.0 (g, C-11, 71.8 (g, C-a), 80.8 (g, Cp), 91.8 (u, C-2), 114.0 (u, C), 123.4 (g, CHI, 124.5 (g, CHI, 126.1 (g, CH), 126.4 (g, CHI, 127.6 (g, CHI, 129.8 (g, CHI, 144.4 (u, C). MS (CI-) mle (relative intensity) 278 (M+, loo), 204 (9), 170 (9), 169 (57), 156 (161, 127 (31). Anal. Calcd (found): C, 73.39 (73.76); H, 5.43 (5.93). [CpCo@,a,l,2-q-( 1-propenyl)naphthalene)l,16. A mixture of 0.93 g (5.17 mmol) of 7 and 0.84 g (5.17 mmol) of 1-(propen-1-y1)naphthalenein 50 mL of petroleum ether was stirred for 3 h a t room temperature and then for 1h a t 45 "C. The green-black solution was filtered, and the filtrate was chromatographed on alumina. With petroleum ether as a mobile phase a green fraction was obtained to give crude 16 after removal of solvent. Recrystallization from petroleum ether a t -25 "C resulted in partial decompostion. [CpCo(g,a,1,2-q-( 1-styryl)naphthalene)l,17. A mixture of 0.88 g (4.89 mmol) of 7 and 1.04 g (4.52 mmol) of l-(p-styryl)naphthalene in 100 mL of petroleum ether was stirred for 15 h a t room temperature and then for 3 h a t 45 "C. An intractable black solid was removed from the dark green solution by filtration. The filtrate was concentrated under reduced pressure. When the concentrate was cooled to 6 "C, dark green crystals precipitated. The crude product was redissolved and chromatographed with petroleum ether/ toluene (1:1, v:v) on alumina. A dark green fraction gave 1.02 g of 17,which was still contaminated with styrylnaphthalene. Repeated recrystallization from petroleum ether a t -25 "C gave a better product, but traces of styrylnaphthalene could not be completely removed. I3CI1H) NMR (CsDs) d 49.2 (C-2 or C-p), 49.8 (C-/3 or C-2), 66.0 (C-a), 82.0 (Cp), 88.6 (C-l), 122.9, 123.7, 124.8, 126.6, 127.3, 128.9, 134.4, 135.6, 137.6. MS (EI) mle (relative intensity) 354 (M+, lo), 289 ([M - Cpl+), 230 (L+, 1001, 215 (16), 202 (lo), 189 ([CpzC01+,51, 152 ([L CsHs]+, 17), 124 ([CpCO]', 3), 114 (18),101 (lo), 77 ([CsH#,
Organometallics, Vol. 14,No.8,1995 3825 6), 66 (7); L = styrylnaphthalene. Anal. Calcd (found): C, 77.95 (75.71); H, 5.40 (5.37).
[(CpCo)2(P,a,1,2-q$',a',3,4-q-(m-distyrylbenzene))l, 18a. A solution of 0.28 g (1.56 mmol) of 7 and 0.18 g (0.64 mmol) of m-distyrylbenzene in 60 mL of petroleum ether was heated for 7 h a t 40 "C. Complex 1Sa (0.23 g, 67%) precipitated as a red-brown solid when the mixture was cooled to room temperature. Attempted chromatography of 18a (alumina, toluene) or recrystallization from toluene resulted in decomposition. Distyrylbenzene was recovered nearly quantitatively.
[(CpCo)&?,a,l,2-q$?',a',4,3-q-(p-distyrylbenzene))l, 18b. A 1.03 g (3.65 mmol) amount of p-distyrylbenzene was suspended in a solution of 1.79 g (9.94 mmol) of 7 in 120 mL of petroleum ether. After 2 h at room temperature the mixture was heated to 35-45 "C. After about 6 h a t this temperature the distyrylbenzene had completely dissolved, and the solution turned dark brown. After the solution cooled to room temperature a green intractable solid was removed by filtration, and the resulting solution was allowed to stand for 2 days. During t h a t time a very small amount of brown crystals separated. Solvent was removed under reduced pressure from the mother liquor to give a dark solid residue and a small amount of red crystals (7 by 'H NMR analysis). The solid was dissolved in a minimal amount of toluene and chromatographed on alumina. After removal of solvent from the first fraction, a pale green solid was obtained, which could not be redissolved in C& or THF. From the second brownish fraction 18b (1.26 g, 65%) was obtained as a brownish-gray powder by crystallization a t -20 "C. Mp, decomp above 60 "C. 13C11H}NMR (C6Ds) 6 48.4 (CH-p,P or CH-2,3), 56.7 (CHp,p' or CH-2,3), 72.8 (CH-a,a'), 82.5 (Cp), 85.9 (C-1,4), 124.6 (CHI, 126.4 (CHI, 126.9 (CH), 128.9 (CH), 146.3 (Ph-Cp,). MS (EI) mle (relative intensity) 282 (L+, 1001, 265 (lo), 203 (17), 189 ([Cp2Col+,111, 178 (181, 141 (10). MS (CI+)mle (relative intensity) 283 ([L + HI+, loo), 282 (L+,301,269 (481,193 (301, 189 ([Cp2Col+,361, 147 (18); L = distyrylbenzene.
[(CpCo)3I~u3-1,2-q:3,4-q:5,6-q-Ip-disty~lbenzene)], 19. 0.21 g (0.75 mmol) ofp-distyrylbenzene was added to a solution of 0.65 g (2.27 mmol) of 8 in 50 mL of THF. The mixture was stirred a t room temperature for 4 h. After the solvent was removed under reduced pressure, a dark solid was obtained, which was redissolved in toluene, filtered, and chromatographed on alumina. Hexamethylbenzene was first eluted with petroleum ether. With toluene/petroleum ether (l:l,v:v) a brown fraction was obtained, which gave 110 mg (28%) of 18b after removal of solvent. Another brown fraction was eluted with toluenelpetroleum ether (2:1, v:v), from which 120 mg (25%) of 19 was obtained after removal of solvent and recrystallization. MS (E11 mle (relative intensity) 282 (L+, loo), 265 (101,203 (121, 189 ([Cp2C01+,lo), 178 (181, 141 (10); L = distyrylbenzene.
[CpCo(l-3,8,9-q-(l-Cp-3-Me-l-cobaltaindenyl~~l, 20. Note: Potassium powder is extremely pyrophoric; residues from filtration may ignite spontaneously in air. A 5.0 g (26.4 mmol) amount of cobaltocene was added to a suspension of 1.3g (33.3 mmol) of potassium powder in 60 mL of diethyl ether a t -50 "C. The slurry was slowly warmed t o room temperature. A 20 mL aliquot of a-methylstyrene was slowly (over approximately 0.5 h ) added at around -10 "C. After 2 h at room temperature all volatiles were removed under reduced pressure. The residue was extracted with 100 mL of n-hexane and filtered. Most of the unreacted cobaltocene was removed from the filtrate by crystallization a t -20 "C. The mother liquor was chromatographed on alumina. Residual cobaltocene was washed from the column with n-hexane. Complex 20 (40 mg, 1% after removal of solvent and recrystallization) was eluted with n-hexaneltoluene (1:1,v:v) as the fourth, green fraction. The first two fractions (1.1g of a red oil, 0.3 g of a light brown oil) did not show Cp peaks in the IH NMR spectrum. IH NMR (C&) 6 2.11 (s, 3H, Me), 4.23 (s, 5H, c p ) , 4.83 (s, 5H, c p ) , 6.76 (''t", l H , H-5 or H-6), 6.89 ("t", l H , H-6 or H-51, 7.21 (d, l H , H-4 or H-7), 8.05 (s, l H , H-2), 8.42 (d, l H , H-7 or H-4).
3826
Wadepohl et al.
Organometallics, Vol. 14, No. 8, 1995
3-Me-l-cobaltaindenyl))], 20. Single crystals were grown Table 10. Details of the Crystal Structure Determinations of from petroleum ether ( E a )or n-hexane (20) and mounted in [CpCo(j3,a,l,2-q-(l-Vinyl)naphthalene)l, 16a, and Lindemann capillary tubes. Intensity data were collected on [CpCo(1-3,8,9-~-~1-Cp-3-Me-1-coba1taindeny1))1 20 Syntex R3 ( E a )or Siemens STOE (20)four circle diffractom15a
20
formula cryst habit, color cryst size [mml cryst system space group
Ci7Hi5C0 Ci9HisCo2 box, dark green needle, dark green 0.3 x 0.3 x 0.8 0.3 x 0.3 x 0.4 orthorhombic tgtragonal Pcab I4 a (A) 8.206(1) 18.150(12) b (A) 11.372(3) c (A) 28.067(7) 9.307(5) v (‘43) 2619(2) 3066(3) Z 8 8 M, 278.30 364.22 d, (g cm-’) 1.411 1.574 Fooo 1152 1488 p(Mo Ka) (mm-l) 1.287 2.152 Mo Ka, graphite X-radiation, i. (A) monochromated, 0.710 69 ambient data collc temp 20 range (deg) 3-50 3-55 hkl range 0-9,0-13,O-33 0-23,O-23,O-12 2308 1878 no. of reflns measd unique 2308 1878 1374 1373 obsd ( I z 2u(I)) abs corr empirical params refinearestraints 17010 19910 GoF 0.953 1.049 R values R (obsd reflns only) 0.050 0.046 wR2 (all reflns) 0.131 0.100 (w = l/[u2(F) + (A.W +BPI) A, B 0.0735, 0 0.0393,0.40 P (max(FO2,0) + 2FC2)/3 l3C(lH} NMR (C6D6) d 19.1 (Me), 79.5 (cp), 80.3 ( c p ) , 109.5 (C), 114.2 (C), 121.1 (CHI, 127.9 (CHI, 128.1 (CH), 153.0 (CH). MS (EI) mle (relative intensity) 364 (M+, 1001, 265 (71, 239 (281, 222 (121, 189 ([Cp&01+, 51), 124 ([cpcol+, 22), 59 (co+, 16). Anal. Calcd (found): C, 62.66 (62.61); H, 4.98 (5.13).
Crystal Structure Determination of [CpCo(P,a,l,2-q(1-vinyl)naphthalene)l,15a, and [CpCo(l-3,8,9-q-(l-Cp-
eters at ambient temperature and corrected for Lorentz, polarization, and absorption effects (Table 10). The structures were solved by the heavy atom method and refined by fullmatrix least-squares based on F using all measured unique reflections. All non-hydrogen atoms were given anisotropic displacement parameters. Some of the hydrogen atoms (those on C2, C11, and C12 in 15a and on C1 in 20) were located from difference Fourier maps and refined with isotropic atomic displacement parameters. All other hydrogen atoms were input in calculated positions. The cyclopentadienyl ring in 1Sa was treated as a “variable metric” rigid regular pentagon. The carboa-carbon bond length within this group refined to 1.393(3)A. The calculations were performed using the programs SHELXS-8634and SHELXL-93.35 Graphical representations were drawn with the ORTEP-I1 program.36
Acknowledgment. This work was supported by the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen Industrie. H.W. gratefully acknowledges the award of a Heisenberg Fellowship. We thank Prof. R. N. Grimes (University of Virginia, U.S.A.) for some of the mass spectra. Supporting Information Available: Tables listing anisotropic atomic displacement parameters, hydrogen atom coordinates, and complete bond distances and angles 15b and 20 (18 pages). Ordering information is given on any current masthead page. OM950161P (34)Sheldrick, G. M. Acta Crystallogr. 1990,A46, 467. (35)Sheldrick, G. M. SHELXL-93;Universitlt Gottingen: Gottingen, Germany, 1993. (36)Johnson, C. K. ORTEP.Report ORNL-5138; Oak Ridge National Laboratory: Oak Ridge, TN, 1965.
