394
Organometallics 1986, 5, 394-397
crystallographic site symmetry is 2/m; O(3) and O(3b) define the two fold rotational axis and 0(2), C(2), Mo, As(2), and C(4) define the mirror plane. The structure of 1 contains a 12-membered ring of alternating CH,As groups and oxygen atoms; these 12 atoms form a flattened cuboctahedron which is trans bicapped by Mo(CO), groups. The As-0 ring configuration and the crystallographic symmetry require a coplanar arrangement for the six oxygen atoms which is sandwiched between two planes of three As atoms each. These exterior planes or arsenic atoms are positioned to form fuc-Mo(CO),L, coordination environments at the metal center. The average of the three Mo-As distances, 2.55(1) A, compares closely to those found in known structure^.^ The average As-0 distance, 1.791 (3) A, is very similar to that found in other caged As(II1)-0 structures: As406(3), 1.80 A;8 As404(CHJ2(41, (av) 1.795(7);9and As303[(CH2),CCH3]( 5 ) (av) 1.77 (1) A.lo The As-Mc-As angles are slightly obtuse, (av) 93.1°, and consistent with octahedral Mo geometry, while the C-Mo-C angles are slightly acute, (av) 87.2 (3)O. Whereas the 0-As-0 angles, (av) 101.0 (l)', are very similar to As406,looo,to 3,101.8 ( 4 ) O , and to 5,100.5', the As-O-As angles in 1, 118.1 (2) and 119.7 (2)O, are considerably smaller than in 3,4, or 5, which are in the range 126-129'. This decrease in the As-0-As angles has the effect of flattening the cubooctahedron and better positioning the six As atoms for metal coordination. Complex 1 is electron precise with a clearly definable 18e count a t each metal center; each As(II1) atom serves as a conventional 2e donor. Our results suggest that the formation and stability of the cyclo-hexaarsaoxane ligand requires the presence of a stabilizing superstructure. The homoatomic cyclopentaarsine precursor to 1 reacts vigorously with dioxygen to form species of empirical formula CH,AsO, but the route to 1 undoubtedly involves considerable metal-centered assistance in the organization of a 12-membered ring. Ellermann et al." have recently reported a novel cryptand (6) containing an eight-membered [N(CH2CH2)3]8(As404)6 alternating As-0 ring in which each As atom is joined to two other A S 4 0 4 rings via N(CH2CH2-)3 tripod bridge networks. The As-0 bond distance (average 1.79 (5) A and the As-O-As (average 118 ( 2 ) O ) and 0-As-0 (average 101 ( 1 ) O ) angles compare closely to those found in 1. To date the known structures containing organoarsaoxane ring systems are either caged by organic linkages, 4-6, or by metal carbonyl coordination, 1, suggesting that such rings may prove to be very difficult to isolate without a superstructure. In fact, NMR studies' clearly indicate the cyclotrimers and tetramers of (CH3AsO), are involved in dynamic reorganization equilibria with higher cyclic and possibly linear species. A complete discussion of the homocyclic decaarsine (6) Crystal data for 1, C,,H,& MozO,z: M,= 995.7, orthorhombic, space group Cmca; a = 13.424 (2) b = 16.909 (3) A, c = 11.818 (2) A, V = 2682.6 (7) A, 2 = 4, Deded= 2.47 g ~ m - F(000) ~, = 1872,~ ( M Ka) o = 80.6 cm-'. A pale yellow crystal (0.33 X 0.34 X 0.35 mm) was grown from CH,Cl,. Data were collected at 23 "C on a Nicolet R3 diffractometer. The structure was solved by direct methods and difference Fourier techniques. The 1605 symmetry-allowed reflections collected (+h, +k, +l; 4O 5 26' 5 50°) were corrected for absorption; of these, 1309 with F, t 4u(F,) were used in refinement with anisotropic parameters for all non-hydrogen atoms. Hydrogen atom contributions were idealized and updated. A t convergence R p = 2.68%, RWVF = 2.94%, and GOF = 1.337 with a 13.4 data to parameter ratio. (7) Rheingold, A. L.; Foley, M. J.; Sullivan, P. J. J. Am. Chem. SOC. 1982, 104, 4727. (8) Bozorth, R. M. J. Am. Chem. SOC.1923,45, 1621. (9) Kopf, J.; Von Denten, K.; Klar, G. Inorg. Chim.Acta 1980,37,67. (10) Mckerley, B. J.; Reinhardt, K.; Mills, J. L.; Reisner, G. M.; Korp, J. D.; Bernal, I. Inorg. Chim. Acta 1978, 31, L411. (11)Ellermann, J.; Veit, A.: Lindner, E.; Hoehne, S. J. 0r.wnomet. Chem. 1983.252, 153.
1,
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complex 2 will appear elsewhere.12 Acknowledgment. The National Science Foundation provided assistance in the purchase of the diffractometer. The Center for Catalytic Science and Technology at the University of Delaware provided support for the research. Registry No. 1,99686-49-4; 2,99686-50-7;MO(CO)~, 1393906-5; cyclo-(AsCHB)B, 20550-47-4.
Supplementary Material Available: Tables of atomic coordinates, a complete listing of bond distances and angles, anisotropic temperature factors, hydrogen atom coordinates, and observed and calculated structure factors (13 pages). Ordering information is given on any current masthead page. (12) Rheingold, A. L.; DiMaio, A.-J.; Fountain, M. E., manuscript in preparation.
Stepwise Assembly of a Trinuclear Bis(carbyne) Complex from Cyclopentadlenylcobalt Units and Bls( trlmethyls1lyl)acetylene: Isolation and Conversion of Cp2M2(RC=CR) and (CpM),( RC=CR) [M = Co and R = (CH,),SI] Bruce Eaton, Joseph M. O'Connor, and K. Peter C. Vollhardt Department of Chemistry University of California at Berkeley and the Materials and Molecular Research Division Lawrence Berkeley Laboratory Berkeley, California 94 720 Received August 26, 1985
Summary: Reaction of (q5-C,H5)Co(C2H& (7) with bis(trimethy1silyl)acetylene(btmsa) in THF at 23 OC gives (~5-C,H,)2Co,(btmsa) (9). The structure of 9 was determined by X-ray crystallography, revealing the presence of a Co-Co double bond: 2.18 A, to our knowledge the shortest cobalt-cobalt bond in existence. Complex 9 reacts further with 7 at 55 OC to produce ($-C,H,),Co,(btmsa) (10). Complex 10 adds carbon monoxide to give ($'-C,H,),Co,(btmsa)(CO) (11). Both 10 and 11 are converted to (T~-C,H~)~CO~[~,-~'-CSI(CH,),] (6) in boiling m -xylene or hot methylcyclohexane. A crossover experiment involving (~5-CH,C,H,),Co2(btmsa) and 10 establishes the intramolecular nature of the rearrangement to 6.
Mononuclear transition-metal complexs of the cobalt triad 1 react with alkynes to give trinuclear bis(carbyne) clusters 2 (Scheme I).1-3 Among the alkyne substrates which have been examined in these reactions, bis(trimethylsily1)acetylene(btmsa) exhibits anomalous behavior. Sakurai and Hayashi have reported that 1 (M = Co) converts to 3 in 93% yield in the presence of 2 equiv of btmsa in boiling ~ y l e n e . ~ More recently, we reported that 1 (M (1) (a) Fritch, J. R.; Vollhardt, K. P. C.; Thompson, M. R.; Day, V. W. J . Am. Chem. SOC. 1979,101,2768. (b) Fritch, J. R.; Vollhardt, K. P. C. Angeru. Chem.,Int. Ed. Engl. 1980,19,559. (c) Fritch, J. R.; Vollhardt, K. P. C. Isr. J . Chem., in press and the references therein. (2) Yamazaki, H.;Wakatsuki, Y.; Aoki, K. Chem. Lett. 1979, 1041. (3) Gardner, S. A.; Andrews, P. S.; Rausch, M. D. Inorg. Chem. 1973, 12,2396. Toan, T.; Broach, R. W.; Gardner, S. A.; Rausch, M. D.; Dahl, L. F. Inorg. Chem. 1977, 16, 279. (4) Sakurai, H.; Hayashi, J. J. Organomet. Chem. 1972,39,365; 1974, 70, 85.
0 1986 American Chemical Society
Organometallics, Vol. 5, No. 2, 1986 395
Communications Scheme I
,Si(CH3),
R
I
e I
b t m r o , M=Co,
M
oc' I
R
2
'co I
AI
0
3
(M=Co,Rh,Ir)
btmso, M = Co
S i (CH3)3 I
c cpco/--(~cccP
C
5
= Co) transforms in refluxing btmsa to produce very low yields of the bis(carbyne) clusters 4 and 5, in addition to a number of mononuclear cobalt complexes and tetrakis(trimethyl~ilyl)butatriene.~*,~ Significantly, none of the hitherto elusive bis[ (trimethylsilyl)(carbyne]complex 6 was observed in these reactions. Concerning the mechanism of bis(carbyne) cluster formation (1 2), a number of fundamental questions remain as to how the trinuclear core assembles and what the structural requirements are for alkyne bond ~leavage.~ Here we report the stepwise formation of a bis[(trimethylsily1)carbynel cluster, 6, from the reaction of (v5C5H5)Co(C,H4),(7) and btmsa. We further demonstrate that the presence of an additional ligand in cyclopentadienyl alkyne clusters of the cobalt triad is not a requirement for bis(carbyne) cluster generation. The presence of a carbonyl ligand in related systems has recently been suggested to reduce the barrier to alkyne cleavage. When (q5-C5H5)Co(C2H4)26 (7; 44 mg, 0.244 mmol, 0.39 M), and excess btmsa (0.73 mmol, 1.18 M) are dissolved in THF-$ and the solution freeze-pump-thaw-degassed five times, the lH NMR spectrum indicates a 1:5 ratio of 7 to a new compound (8, Scheme 11) with chemical shifts at 6 4.59 (s, 5 H), 2.40 (half of an AA'BB' pattern, 2 H), and 0.36 (s, 18 H).' A 13C(lH]NMR spectrum of the sample has resonances assigned to 8 at 6 98.46 [C,(Si(CH3)3]2],84.16 (C5H5),34.79 (C,H,), and 1.39 [Si(CH3)3].s On the basis of the NMR data, we formulate the structure of 8 as (V~-C~H~)CO(C,H~)[C~(S~(CH~)~)~]. Attempts to
-
(5)Clauss, A. D.;Shapley, J. R.; Wilker, C. N.; Hoffmann, R. Organometallics 1984,3, 619. See also: Chi, Y.; Shapley, J. R. Organometallics 1985,4, 1900. (6)7: 'H N M R (THF-d8)6 4.66 ( 8 , 5 H),2.56,0.51(AA'BB', 8 H); 'H NMR (benzene-d6)6 4.28 ( 8 . 5 H), 2.53,0.65 (AA'BB', 8 H).Jonas, K.; Deffense, E.; Habermann, D. Angew. Chem., Znt. Ed. Engl. 1983,22,716. Angew. Chem. Suppl. 1983,1005. (7)The other half of the AA'BB' pattern is presumably obscured by the large resonances for btmsa at 6 0.36 and 0.14. In addition to the resonances for 7 and 8, a singlet is observed at 6 5.37 for uncomplexed ethene. (8)Additional signals a t 6 85.7 and 37.8 are assigned to 7, signals a t 6 114.0 and 0.19 to uncomplexed btmsa, and a signal at 6 123.5 is attributed to uncomplexed ethene.
Figure I. ORTEP drawing of 9. Ellipsoids are scaled to represent the 50% probability surface.
isolate 8 by evaporation of the solvent mmHg, 12 h) result in formation of an air-sensitive maroon solid, 9. The mass spectrum and elemental analysis of 9 indicate a bimetallic formulation of composition (C5H5),Co2[C2Si(CH3)3)2].g A highly symmetrical structure for 9 is required by the 'H NMR (benzene-d,) spectrum, which has singlets at 6 4.22 (10 H)and 0.19 (18 H). An indication of the nature of its structure is provided by the extremely (9)(a) 9: mp (sealed capillary) 184-190 OC dec; 'H NMR (benzene-d6) 6 4.22 ( 8 , 10 H), 0.19 ( 8 , 18 H); 13C(1H} NMR (THF-d8, -30 "C) 6 172.8, 84.9,0.02;IR (THF) 1578 (s), 1244 ( 8 ) cm-l; HRMS calcd for C18HzsCo$3iz 418.0394,found 418.0385. Compound 9 is best purified by sublimation (75% yield). (b) While this work was in progress, the reaction of 7 with of unspecified structure was briefly btmsa to give (~5-C6H&Coz(btmsa) mentioned in a review article: Jonas, K. Angew Chem., Znt. Ed. Engl. 1985,24,295.(c) All new isolated compounds gave satisfactoryanalytical and spectroscopic data. (10)Crystal data: crystal size 0.23 X 0.30 X 0.30 mm, space group P2'/c, a = 15.2917 (16)A, b = 9.0636(8)A, c = 15.9110 (11)A, V = 2190.8 ~ 16.2 ~ ~ cm-', deded= 1.27 g ~ m - Enraf-Nonius ~, CAD-4 dif(6)A3, G , = fractometer, radiation Mo Koc (A = 0.71073A), scan r e 3 ' 5 28 < 45O, reflections collected 3195, unique 2179 with F > 303),R = 0.029,R, = 0.0385. Inspection of the azimuthal scan data showed a variation Zmin/Ima = 0.93 for the average curve. An empirical correction for absorption, based on the azimuthal scan data, was applied to the intensities.
396 Organometallics, Vol. 5, No. 2, 1986
Communications
+
Scheme I1
CpCo(CH2=CH2)2
-
-
btmsa
S~(CHS)~
I
cpco=
I
S'i (C H 3 )
7
=cocp
Si(CH3),
8
9
(C H 3 ) 3 Si
--7
cpco
-
/Si(CH3)3
co
-6 o c p
--I
\
\
cpco C
IO
Ill
0
(CH3)3Si
I
6
facile CO uptake (23 "C) to give 3.4 In order to unambiguously determine the geometry of the btmsa ligand with respect to the cobalt-cobalt bond and because of the unusual features of this compound, an X-ray diffraction study was performed (Figure 1).Io The structure consists of a bridging btmsa unit oriented perpendicular'l to the cobalt-cobalt axis. The Co-Co bond length of 2.185 A is consistent with the presence of a cobalt-cobalt double bond and is, to our knowledge, the shortest cobalt-cobalt distance hitherto measured.12 The C1-C2 bond length (1.336 A) is typical of a double bond. When a diethyl ether solution of 9 (135 mg, 0.32 mmol, 0.16 M) and 7 (0.46 mmol, 0.02 M) is sealed in a vial under vacuum at -77 "C and heated at 55 "C for 33 h, a new trinuclear btmsa cluster, is formed in 70% isolated yield (chromatography, alumina 11, 10% diethyl etherhexane). The 'H NMR (benZene-d6) spectrum at 20 "C consists of a singlet at 6 4.18 (15 HI, assigned to the protons of three equivalent C5H5ligands, and a broad resonance (11) Hoffman, D. M.; Hoffman, R. J. Chem. Soc., Dalton Trans. 1982, 1471. (12) Compare the metal-metal bond lengths in Coz(CO)~(Cz-t-Buz), 2.46 A, [q*-C~(CH&]&~(CO)2, 2.34 A, (&2&I&F&-NO)2,2.326 A, and Fe2(CO),(C2t-Bu2),2.316 A. Cotton, F. A.; Jamerson, J. D.; Stulta, B. R. J. Am, Chem. SOC. 1976,98,1774. Ginsburg, R. E.; Cirjak, L. M.; Dahl, L. F. J. Chem. SOC.,Chem. Commun. 1979,468. Bailey, W.I.; Collins, D. M.; Cotton F. A,; Baldwin, J. C.; Kaska, W. C. J. Orgonomet. Chem. 1979,165, 373. For related diiron com ounds with two perpendicular bridging alkyne ligands (Fe-Fe 2.22 see: Nicholas, K.; Bray, L. S.; Davis, R. E.; Pettit, R. J. Chem. SOC., Chem. Commun. 1971, 608. Schmitt, H.-J.; Ziegler, M. L. 2. Naturforsch.,B Anorg. Chem., Org. Chem. 1973,28B,508. (13) 10: mp (sealed capillary) 212-215 OC; 'H NMR (benzene-d,, 20 "C) 8 4.18 (8, 15 H), 0.27 (br 8,18 H); 'H NMR (benZene-d,, 80 "C) 6 2.99 (s, 15 H), 0.02 (a, 18 H); 'H NMR (THF-d8, -100 "C) 6 5.20 (5, 5 H), 4.83 (s, 10 H), 1.03 (8, 3 H), 0.62 (8, 6 H), -0.08 (S, 9 H); l3CI1HlNMR (THF-dS, -60 "C) 6 212.39,80.49, 77.26,5.76, 5.08, 3.53 (only one of the sp carbons was observed); 13C('H)NMR (THF-de, 21 "C) 6 84.8,4.25 (the sp carbons were not observed); IR (THF) 1242 cm-'; HRMS calcd for C23H33C03Si2 542.0117, found 542.0103.
8
I Si(CH3),
at 0.27 (18 H), assigned to the protons of a fluxional btmsa. A t 80 "C, these resonances are sharpened and shift to 6 2.99 (s, 15 H) and 0.02 (s, 18 H). The lH NMR (THF-dJ spectrum of 10 at -90 "C consists of singlets at 6 5.20 (5 H) and 4.83 (10 H), which are assigned to the protons of a unique and two equivalent C5H5ligands, respectively. Singlets are also observed at 6 1.03 (3 H), 0.62 (6 H), and -0.08 (9 H) and are attributed to the protons of two unique trimethylsilyl groups, one of which exhibits hindered rotation about the sp-carbon-silicon bond. To our knowledge, such behavior is unprecedented for a complexed (trimethylsily1)alkyne and may have its cause in the coordinatively unsaturated nature of the cluster. The observation of nonequivalent trimethylsilyl units suggests an assignment of the btmsa ligand as perpendicular to one cobalt-cobalt bond in the frozen conformation. A crystal structure determination has been reported by Dahl for the isoelectronic alkyne cluster Fe3(C0)9(Ph2C2).14 Exposure of THF solutions of 10 to carbon monoxide (1 atm) at 23 "C results in formation of a second btmsa cluster llgC,l5 (40% yield). Hexane solutions of 11 have a strong, sharp band in the IR spectrum at 1700 cm-', indicative of a triply bridging carbonyl ligand.16 The 'H NMR (acetone-d6)spectrum has resonances at 6 4.02 (s, 15 H, C5HJ and 0.54 [s, 18 H, Si(CH,),], which remain (14) Blount, J. F.; Dahl, L. F.; Hoogzand, C.; Hubel, W. J.Am. Chem. SOC.1966,88, 292. (15) 11: mp (sealed capillary) 295 "C dec; 'H NhlR(acetone-d,) 6 4.02 (s, 15 H), 0.54 ( 8 , 18 H);IR (hexane) 1700 cm-'; HRMS calcd for C03Si2C24H330 570.0066, found 570.0071. (16) For comparison (?*-C,H,)sRh3(CO)(PhZCz) has bands at 1693 (sh) and 1678 ( 8 ) em-': (t+'-C5H5)31r,(CO)(Ph2C2)at 1736 (s) em-'? and (q5C5H5)3C03(CO)(C,(CF3)2) at 1698 cm-'.17 (17) Freeman, M. B.; Hall, L. W.; Sneddon, L. G.Inorg. Chem. 1980, 19, 1132. (18) 6: mp 246-248 OC; 'H NMR (benzene-de) 6 4.44 (s, 15 H), 0.79 (s, 18 H); 13C('H)NMR(THF-d8,-60 "C) 8 363.2, 83.2, 4.25; mp 246-248 "C;HRMS calcd for Cz3H3,Co3Siz542.0177, found 542.0103.
Organometallics 1986,5, 397-398
sharp even at -88 OC. Thus, the addition of a triply bridging carbonyl ligand to 10 greatly reduces the barrier to alkyne rotation on the face of the trinuclear core. When a m-xylene solution of 10 is heated under nitrogen for 36 h, followed by evaporation of the volatiles and chromatography of the residue, a pink, air-stable, crystalline solid 6 is isolated in 69% yield.9cJs The 'H NMR (acetone-de)spectrum has singlets at 6 4.56 (15 H, C5H5) and 0.82 [18 H, Si(CH,),], and the 13C(lHJNMR (THF-$, -60 "C) spectrum has a resonance at 6 363 assigned to the carbyne carbon1 Similarly, when 11 is heated in m-xylene at reflux for 36 h and the volatiles are evaporated, a 'H NMR (benzene-d,) spectrum of the residue indicates a 2:l ratio of 3 to 6 (35% isolated yield of 6). The reactions of 10 and 11 to give 6 are particularly interesting in light of a recent report that (q5-C5H5),M3(CO)(C2Ph2) [M = Rh, Ir] are converted to (q5C5H5)3M3(CPh)2 with no evidence for an unsaturated Cp3M3(C2Ph2)specie^.^ On the basis of the experimental data and a theoretical analysis for the corresponding reaction of ( v ~ - C ~ H ~ ) ~ M ~ ( C ~ an H ~unsaturated ) ( C O ) , alkyne intermediate, (q5-C5H5),M3(C2R2), was discounted. The proposed mechanism invoked an edge-bonded alkyne which underwent a carbonyl shift (k3 to terminal) concerted with alkyne cleavage. In order to rule out the intervention of an arene complex in facilitating the conversion of 10 to 6, the same reaction was carried out in methylcyclohexane, providing the product at the same rate. To provide proof for the intramolecularity of this transformation and to rule out reversible dissociation of q5-C5H5Cofrom 10, formation (V~-C~H,),CO~(PL-CR)~ and reassociation to furnish 6 (as suggested by a reviewer) a crossover experiment was performed. Thus, heating 10 in the presence of (q5CH3C5H4)2C02(btmsa)gcJg gave 6 and the unchanged labeled dinuclear cluster without any sign of crossover. In conclusion, we now have evidence for the sequential conversion of a mononuclear cobalt precursor 7 to mononuclear 8, dinuclear 9, and trinuclear alkyne 10 complexes, with ultimate formation of a trinuclear bis(carbyne), 6. The entire process represents the first well-characterized case of alkyne-mediated assembly of a trinuclear bis(carbyne). In addition, we have demonstrated that the presence of an additional ligand in trinuclear cyclopentadienylcobalt is not a requirement for alkyne scission.
Acknowledgment. The crystal structure analysis was carried out by Dr. F. J. Hollander, staff crystallographer at the U.C. Berkeley, Department of Chemistry X-ray facility (CHEXRAY). This work was supported by NSFCHE 8504987. K. Peter C. Vollhardt is a Miller Professor in Residence (1985-1986).
Supplementary Material Available: A listing of positional and thermal parameters and tables of bond lengths, bond angles, a n d structure factors of 9 (22 pages). Ordering information is given on a n y current masthead page.
(19)Made in a manner analogous to 9 via (qS-CH3C&4)Co(C2H4)2 ['H NMR (benzene-d,) 6 4.56 (dd, J = 1.9,1.8Hz, 2 H), 4.11 (dd, J = 1.8,1.6 Hz, 2 H), 2.42,0.79 (AA'BB', 8 H), 1.26 ( 8 , 3 H); I3C NMR (benzene-d ) 6 96.40,86.13,84.56,39.21,11.881 by treatment with btmsa to give (qgCH3C5H1)2C02(btmsa) ['H NMR (THF-ds) 6 4.58 (dd, J = 1.9,1.8 Hz, 4 H), 3.89 (dd, J = 1.8,1.7 Hz, 4 H), 1.84 (s, 6 H), 0.27 ( 8 , 18 H)].
0276-7333/86/2305-0397$01.50/0
397
Metathesis-Like Reaction of a Tungsten Alkyildyne Complex with Cyclohexyl Isocyanate' Karin Weiss, Uirich Schubert,$and Rlchard R. Schrockg Laboratorium fur Anorganische Chemie der Universitat Bayreuth, Postfach 3008 8580 Bayreuth, West Germany, Institut fur Anorganische Chemie der Universitat Wiirzburg, Am Hubland 8700 Wurzburg, West Germany, and Department of Chemistty, Room 6-331 Massachusetts Institute of Technology Cambridge, Massachusetts 02 139 Received August 5, 1985
Summary: The reaction between W(C-t-Bu)( 1,2dimethoxyethane)Cl, and cyclohexyl isocyanate is proposed to yield an intermediate containing a cyclohexylimido and a ketenyl ligand. A second cyclohexyl isocyanate then inserts into the tungsten-carbon single bond of the ketenyl ligand to form an oxazetin tungstenacycle. Crystals of the final product are monoclinic with a = 9.311 (9) A, b = 16.60 (2) A, c = 14.91 (I) A, p = 100.26 (7)O, v = 2268.1 A3, space group P2,lc, Z = 4, and d(calcd) = 1.79 g/cm3.
Reactions between carbyne or alkylidyne complexes and organic compounds containing a double bond are rare. Two examples are addition reactions of heterocumulenes like S022to carbyne complexes prepared by Roper and addition of COZ3to Fischer-type carbyne complexes. We report here a metathesis-like reaction between cyclohexyl ibocyanate and W(C-t-Bu)(dme)Cl, (dme = 1,2-dimethoxyethane). This reaction is one example of what is likely to be a class of reactions whose crucial feature is a metathesis-like or Wittig-like4 reaction of the alkylidyne ligand. Addition of 2 equiv of cyclohexyl isocyanate in dichloromethane at 0 OC to 224 mg of W(C-t-B~)(dme)Cl,~ yields a deep red reaction mixture from which red crystals can be obtained (260 mg, 85% yield) upon addition of pentane., An X-ray structural study7shows the product to be the molecule W(NCy)[N(Cy)C(O)C(CO)(t-Bu)]Cl, (1; Figure 1)containing three meridional chloride ligands, a cyclohexylimido ligand, and a bidentate, ketenyl-subUniversitat Bayreuth.
* Universitat Wurzburg.
*(1)Massachusetts Institute of Technology. Investigations of Polymerizations and Metathesis Reactions.
6. For Part 5 see: Weiss, K.;Krauss, H. L. J. Catal. 1984,88, 424. (2)Wright, A. H. Ph.D. Thesis, University of Auckland, 1983. Filippou, A. C.; Alt, H. G.; Thewalt, U. Angew. (3)Fischer, E. 0.; Chem. 1985,97,215;Angew. Chem. Int. Ed. Engl. 1985,24,203. (4)See: Freudenberger, J. H.; Schrock, R. R.; following paper in this issue. (5)Schrock, R. R.; Clark, D. N.; Sancho, J.; Wengrovius, J. H.; Rocklage, s. M.; Pedersen, s. F. Organometallics 1982,I , 1645. (6)Partial 13CNMR 6 184.8 and 183.5 (C=C=O and NC=O), 73.3 (=NCH), 61.4(-N-CH),50.5 (C=C=O). IR (cm-I): 2110 (vs, C=C==O), 1605 (m, NCO), 1620 (m, NCO). Mass spectrum parent ion observed in the region m / e 610 with appropriate isotopic pattern. (7) Crystals were grown from CDCls A total of 2577 independent reflections (2O 5 28 5 48O,Mo Ka radiation, Syntex P21 diffractometer) were used to solve the structure by the Patterson method (Syntex XTL). Empirical absorption, Lorentz, and polarization corrections were applied. Hydrogen positions were found by difference Fourier methods or were calculated according to ideal geometry. Full-matrix least-squares refinement with anisotropic thermal parameters for all non-hydrogenatoms (hydrogen parameters were not refined) led to R = 0.083and R, = 0.087 (l/w= u2), all structure factors included.
0 1986 A m e r i c a n C h e m i c a l Society
