2164
Organometallics 1995, 14, 2164-2166
Synthesis and Characterization of a (Keteny1)metal Cluster Complex, an Intermediate in the Oxidative Decarbonation of an Acetylide Ligand Te-Kun Huang,? Yun Chi,*??Shie-Ming Peng,*l$Gene-Hsiang Lee,$ Sue-Lein Wang,? and Fen-Ling Liaot Departments of Chemistry, National Tsing Hua University, Hsinchu 300, Taiwan, and National Taiwan University, Taipei 107, Taiwan Received January 17, 1995@ Scheme 1
Summary: Oxidation of the acetylide cluster Cp*WOs3(CO)9(C2)(C2ph) (2) in toluene produced the ketenyl complex Cp*WOs3(CO)dCd(OC2ph) (3). Compound 3 releases a CO group to afford the alkylidyne cluster CpyW0s3(CO)9(Cd(CPh) (4) upon heating, which provides an example of sequential conversion of acetylide to ketenyl and alkylidyne. Many examples of transition-metal complexes containing ketenyl ligands have been prepared, and their chemistry is under active investigati0n.l However, one important reaction that has not been well-documented is C-C bond cleavage to afford a coordinated alkylidyne (eq 1). Such ketenyl complexes have been proposed as speculative intermediates for the oxidative decarbonation of acetylide complexes by Vahrenkamp2 and may be of relevance to oxygen-induced ligand fragmentation3 and oxo-hydrocarbyl ligand coupling r e a ~ t i o n s .Herein ~ we report the studies of the ketenyl cluster Cp*WOs3(CO)g(CZ)(OCzPh),which was prepared from direct reaction of the acetylide cluster with oxygen and shows a reversibe equilibrium with the alkylidyne cluster. The overall reaction provides a model for the involvement of a ketenyl ligand in the acetylide to alkylidyne transformation (eq 2) via consecutive oxygen atom transfer and elimination of a CO ligand on metal clusters.
During our investigation on the interaction of highly unsaturated substrates on polynuclear cluster comNational Tsing Hua University. National Taiwan University. @Abstractpublished in Advance ACS Abstracts, April 1, 1995. (1) (a)Geoffrey, G. L.; Bassner, S. L. A d u . Orgammet. Chem. 1988, 28, 1. (b) Casey, C. P.; Fagan, P. J.; Day, V. W. J . Am. Chem. SOC. 1982,104,7360. (c) Chisholm, M. H.; Huffman, J. C.; Marchant, N. S. J . Chem. Soc., Chem. Commun. 1986, 717. (d) Kreissl, F. R.;Sieber, W.; Wolfgruber, M. Angew. Chem., Int. Ed. Engl. 1983,22, 493. (2) (a) Bernhardt, W.; Vahrenkamp, H. Organometallics 1986, 5, 2388. (b) Bemhardt, W.; Vahrenkamp, H. J. Organomet. Chem. 1990, 383,357. (c) Shaposhnikova, A. D.; Stadnichenko, R.A.; Kamalov, G. L.; Pasynskii, A. A.; Eremenko, I. L.; Nefedov, S. E.; Struchkov, Y. T.; Yanovsky, A. I. J . Organomet. Chem. 1993,453, 279. ( 3 )(a)Boyar, E.; Deeming, A. J.; Kabir, S. E. J . Chem. SOC.,Chem. Commun. 1986, 577. (b) Doherty, E. D.; Filders, M. J.; Forrow, N. J.; Knox, S. A. R.;Macpherson, K. A.; Orpen, A. G. J . Chem. Soc., Chem. Commun. 1986, 1335. (4) (a) Herrmann, W. A. Angew. Chem., Int. Ed. Engl. 1988, 27, 1297. (b) Carney, M. J.;Walsh, P. J.; Hollander, F. J.;Bergman, R.G. Organometallics 1992, 11, 761. (c) Henmann, W. A,; Roesky, P. W.; Scherer, W.; Kleine, M. Organometallics 1994, 13, 4536. +
t
CO'lCO)
Ph
CP'
" P '
,o.
p ~ u n d s we , ~ were able to synthesize the novel diynyl cluster Os3(CO)~o[PhC4WCp*(CO)~] (l),in which the remote acetylenic C-C triple bond is tightly coordinated to the Os3 triangular core via a 2a n mode (Scheme 1). Compound 1 was prepared by a 1:l combination of Oss(CO)lo(NCMe)zand the mononuclear diyne complex Cp*W(C0)3(C4Ph)in refluxing toluene.6 Further thermolysis of 1 in toluene (110 "C, 1 h) leads to the formation of the acetylide-dicarbide cluster Cp*WOss(CO)g(Cz)(CzPh) (2) in 57% yield as a result of the cleavage of the diynyl C(sp)-C(sp) single bond.7 Red, needle-shaped single crystals of 2 were obtained from a methanol-dichloromethane solution, and definitive proof of the structure was elucidated by X-ray crystallography.8
+
(5)(a) Chiang, S.-J.; Chi, Y.; Su, P.-C.; Peng, S.-H.; Lee, G.-H. J. Am. Chem. Soc. 1994,116,11181. (b) Peng, J.J.;Horng, K.-M.; Cheng, P.-S.; Chi,Y.; Peng, S.-H.; Lee, G.-H. Organometallics 1994,13,2365. (6) Selected data for 1 are as follows. IR (CeH12): v(C0) 2097 (w), 2064 (vs), 2053 (s), 2025 (vs), 2004 (m),1945 (s), 1935 (e), 1838 (br, vw)cm-1. 13C NMR (CDCl3, 294 K): CO, 6 232.8 (Jw-c = 124 Hz), 215.7 (Jw-c = 144 Hz, 2CO), 177.4 (br, lOC, Os-CO); 6 151.2 (i-C6H5), 146.3 (Cd), 141.8 (Jw-c = 20 Hz, C ), 129.0 (o,m-C&, 2 0 , 1 2 7 . 7 (m,oC6H5, 2 c ) , i 2 7 . 4@-C6H5),119.2 104.8 ( C a e s ) , 101.0 ( J ~=-90~ Hz, C,J, 10.8 (Me). Anal. Calcd for C33H200130s3W C, 28.74; H, 1.46. Found: C, 28.61; H, 1.48. (7) Spectral data for 2 are as follows. MS (FAB, lg20s,lE4W):m/z 1272 (M+). IR (Cd312): v(C0) 2082 (s), 2067 (w), 2059 (vs), 2012 (s), 1999 (vs), 1981 (m), 1964 (m), 1949 (w) cm-l; lH N M R (CDCls, 294 K): 6 7.34 (d, 2H,JH-H= 8.0 Hz),7.26 (t, 2H,JH-H = 8.0 Hz), 7.15 (t, lH, JH-H= 8.0 Hz), 2.29 ( 8 , 15H, Cp*). 13C N M R (CDC13, 294 K): CO, 6 217.2 (Jw-c = 171 Hz), 184.4, 181.7, 179.2, 177.6 (3'3, 175.3, 173.5; 6 306.4 (Jw-c = 158 Hz, CCPh), 172.2 @4-C2), 145.9 @4-C2), 138.8 (iC6H5), 129.2 (o,m-CaHs,2c),128.2 (m,o-C&, 2c), 127.1 @-cd35),105.7 (C5Me6),67.1 (CCPh), 12.4 (Me). Anal. Calcd for C29H20090~3W:C, 27.49; H, 1.59. Found C, 27.45; H, 1.64. (8) Crystal data for 2: C.&Im0908 W, monoclinic, P 2 h , a = 14.053( 5 )A, b = 10.255(2)A,c = 22.495(7) j3 = 106.35(3)",V = 3110(2)A3, 2 = 4, F(000)= 2272, p(Mo Ka) = 15.95 mm-', 2812 reflections with I > 3dI) and 380 parameters, R = 0.041, R , = 0.035, GOF = 0.99.
(e,),
1,
0276-7333/95/2314-2164$09.00/00 1995 American Chemical Society
Organometallics, Vol. 14,No. 5, 1995 2165
Communications
n C16 fi
Figure 1. Molecular structure of 2. Selected bond lengths (A)are as follows: Os(l)-Os(2) = 2.760(2),Os(2)-Os(3) = 2.809(2), 0~(2)-W(1)= 2.801(2), 0~(3)-W(l)= 2.846(2), 0~(2)-C(10)= 2.19(2),W(l)-C(lO) = 1.92(2), Os(l)-C(ll) = 2.09(2), 0 ~ ( 2 ) - C ( l l )= 2.29(2), C(lO)-C(11) = 1.36(2), C(ll)-C(l2) = 1.52(3),Os(l)-C(18) = 2.13(2), 0~(2)-C(18) = 2.20(2), W(l)-C(18) = 2.43(2), 0~(2)-C(19)= 2.26(2), 0~(3)-C(19)= 1.99(3),W(1)-C(19) = 2.25(3),C(lS)-C(lS) = 1.25(3). The structure of 2 consists of a spiked-triangular core arrangement with the 0 4 3 ) atom located at the pivotal position (Figure 1). The dicarbide ligand adopts a novel p4 mode, in which the carbon atoms are linked to the Os(1) and Os(2) atoms via two a-bonds and coordinated to the metal atoms Os(3) and W(1) via z-interactions. The atoms Os(l), Os(21, and Os(3) and the dicarbide fragment C(18)-C(19) are close to coplanar. The C(18)C(19) length (1.25(3) which is intermediate between the C-C distances of the complexes CpW(C0)3(C2)W(CO)3Cp (1.18(3) A)g and CpWOs3(CO)11@4-CzPh) (1.38(2) &lo and resembles that of the complexes COSRe2(C2)(C0)14 (1.28(2) and CpWOs2(CO)e(CzPh) (1.23(5) A),12 confirms the presence of C-C multiplebond character, which is also similar to that observed in R~~@-PP~~)s(CS)(CO)~S.~~ The dicarbide ligand showed signals a t 6 172.2 and 145.9 in the 13C NMR spectrum. These chemical shifts are similar to those observed for [ F ~ ~ ( C O ) ~ { C ~ F ~ ( C O )(6Z C 172.9,132.2) ~}Iand [CpFeCoz(CO)6{C2Fe(C0)2Cp}] (6 207.7, 154.4).14 In addition, the acetylide ligand adopts a novel p~3-)7~:)7~:)7~ mode,15 in which the P-carbon is linked to the Os(1) and Os(2) atoms via two single bonds (Os(l)-C(ll) = 2.09(2) A and Os(2)-C(ll) = 2.29(2) and the a-carbon is linked to the W(l)-Os(l) edge with substantial carbynic character (Os(2)-C(lO) = 2.19(2) A and W(l)-C(lO) = 1.92(2) 8).In accordance with the above description,
A),
A)
(9) Chen, M.-C.; Tsai, Y.-J.; Chen, C.-T.; Lin, Y.-C.; Tseng, T.-W.; Lee, G.-H.; Wang, Y. Organometallics 1991,10, 378. (10)Chi, Y.; Wu, C.-H.; Peng, S.-M.; Lee, G.-H. Organometallics 1990,9, 2305. (11)Weidmann, T.; Weinrich, V.; Wanger, B.; Robl, C.; Beck, W. Chem. Ber. 1991,124,1363. (12) Hwang, D.-K.; Chi, Y.; Peng, S.-M.; Lee, G.-H. Organometallics 1990. 9..2709. ~.. -(13)Bruce, M. I.; Snow, M. R.; Tiekink, E. R. T.; Williams, M. L. J. 1 - 1 -
Chem. Soc., Chem. Commun. 1986,701. (14) (a)Jensen, M. P.; Sabat, M.; Shriver, D. F. J. Cluster Sci. 1990, 1, 75. (b) Akita, M. Terada, M.; Moro-oka, Y. Organometallics 1992, 11, 1825. (15)The common bonding of the p3-acetylide ligand involves the u + 21c mode; see: Sappa, E.; Tiripicchio, A,; Braunstein, P. Chem. Rev. 1983,83, 203.
Figure 2. Molecular structure of 3. Selected bond lengths (A) are as follows: Os(l)-Os(2) = 2.769(2), Os(2)-Os(3) = 2.789(2),W-Os(2) = 2.795(2),W-Os(3) = 2.871(2),W-O(10) = 2.18(2), C(10)-0(10) = 1.25(3), 0~(2)-C(lO)= 2.27(3), W-C( 10) = 2.01(3), OS(l)-C(ll) = 2.06(3), Os(2)-C(ll) = 2.40(3), C(lO)-C(ll) = 1.48(4), C(ll)-C(12) = 1.47(3), Os(l)-C(18) = 2.08(3), 0~(2)-C(18)= 2.19(2), W-C(l8) = 2.47(3), 0~(2)-C(19)= 2.23(3), 0~(3)-C(19)= 2.04(3), W-C(19) = 2.21(3), C(18)-C(19) = 1.20(4).
the signals for the p-CzPh ligand in the I3C NMR spectrum are found at 6 306.4 (Ca, Jw-c = 158 Hz) and 67.1 (Cp). The downfield shift and the large Jw-c coupling constant of its a-carbon suggests that there is considerable multiple-bond character in this tungstencarbon bond. Treatment of 2 with oxygen in toluene solution (1atm, 110 "C, 1 h) afforded the ketenyl cluster Cp"WOs3(CO)g(Cz)(OCzPh)(3),which was isolated in 70% yield after recrysta1lization.l6 The X-ray diffraction study17 confirms that it possesses a WOs3@&) core identical with that of 2, on which the acetylide of 2 has converted into a ketenyl ligand with the oxygen atom bridging the W-C(10) bond (Figure 2). The insertion of a n oxygen atom weakens the bonding capability of the C(lO)C(ll)Ph unit, increasing the W-C(l0) distance from 1.92(2) to 2.01(3) the Os(2)-C(ll) distance from 2.29(2) to 2.40(3) A,and the C(lO)-C(ll) distance from 1.36(2) to 1.48(4) A with respect to the structural data of 2. The 13CNMR spectrum exhibits dicarbide resonance signals a t 6 141.4 and 119.9 and ketenyl signals a t 6 210.9 (Ca, Jw-c = 51 Hz) and 137.4 (Cp). Of note are the chemical shift and the Jw-c coupling constant of the ketenyl a-carbon, which are consistent with the lengthening of the W-C(l0) distance with respect to that in 2. The reactivity of 3 was examined. As expected, complex 3 was found to react slowly in refluxing toluene
A,
(16) SDectral data for 3 are as follows. MS (FAEL 1920s. 184W): m/z 1288 (MT). IR (CsH12)' v(C0) 2086 (m), 2067 (vsc2017 (s), 2009 (m), 2001 (s), 1982 (m), 1973 (m), 1950 (w), 1882 (br, w) cm-'; 'H NMR (CDC13,294 K):6 7.09-7.27 (m, 5H, Ph), 2.02 (8, 15H, CP*). l3C NMR (CDCl3,294 K): CO, 6 221.7 (Jw-c = 169 Hz), 185.6,179.9 (2Ch 177.3, 175.9 (br, 3C),173.4; 6 210.9 (Jw-c = 51 Hz, CCPh), 148.1 (Z-CgHd, 141.4 +&), 137.4 (CCPh), 128.2 (o,m-Cd&, 2C), 127.9 (m,O-CGHS,ZC), 126.8 @-C6H5), 119.9 (Uq-Cz), 109.1 (C5Med, 112 (Me). Anal. Calcd for CzgHzo01oOs3W C, 27.15; H, 1.57. Found: C, 27.10; H, 1.63. O S ~ W , P21/c, a = (17) Crystal data for 3: C ~ ~ H ~ ~ O I ~monoclinic, 20.906(3) A, b = 14.274(4)A, c = 10.634(3)A, /3 = 97.20(2)", V = 3148(1)A3, 2 = 4, F(OO0)= 2283, p(Mo Ka)= 15.85 mm-', 3449 reflections with I > 2dZ) and 389 parameters, R = 0.066, R, = 0.073, GOF = 2.83.
Communications
2166 Organometallics, Vol. 14, No. 5, 1995 under Nz to form the alkylidyne cluster Cp*WOs3(CO)g(Cz)(p&Ph) (4; 5 h, 56%) (Scheme 1). However, thermolysis of 3 under CO a t 1 atm produced 4 in much higher yield (92%). Complex 4 was fully characterized by an X-ray analysis and spectroscopic methods.ls The key spectral feature involves the observation of five CO signals at 207.0 (Jw-c = 141 Hz), 189.9, 183.1, 177.0 (br, 3 0 , and 175.5 (3C), two dicarbide signals at 6 162.5 and 155.3, and an alkylidyne C, signal at 6 315.3 (Jw-c = 93 Hz) in its 13C NMR spectrum. In conclusion, this work provides the crucial mechanistic evidence for the oxidative decarbonation of acetylide ligands. Although the acetylide ketenyl alkylidyne sequence is the dominant pathway in our experiment and other systems comprising metal cluster compounds,z generation of a stable ketenyl derivative from acetylide and its subsequent conversion to alkylidyne ligands has never been achieved in mononuclear and dinuclear metal complexes; only the reversals were d0~umented.l~ The oxophilic W atom appears to be the
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(18)Selected data for 4 are as follows. MS (FAB, 1920s, Ia4W): m/z 1260 (M+). IR (CsHiz): Y(CO)2074 (vw),2054 (vs), 2043 (vw),2004 (s), 1997 (m), 1984 (vw), 1978 (vw),1962 (w), 1937 (VW)cm-'. 'H NMR (CDCl3, 294 K): 6 7.62(d, JH-H= 7.5Hz, 2H), 7.39(t,JH-H= 7.5Hz, 2H), 7.29 (t, JH-H = 7.5 Hz, lH), 2.21 ( 8 , 15H,Cp*). Crystal data: CzaHzo0190s3WCHzC12,triclinic, P1,a = 11.022(2)A, b = 11.304(2) A, c = 13.488(3)A, a = 78.84(2)",B = 77.28(2)",y = 88.46(2)";R = 0.027.Details of the structure determination will be given in a full publication. (19)(a) Kreissl, F. R.; Frank, A.; Schubert, U.; Lindner, T. L.; (b)Kreissl, Huttner, G. W. Angew. Chem., Znt. Ed. Engl. 1976,15,632. F. R.; Eberl, K.; Uedelhoven, W. Angew. Chem., Int. Ed. Engl. 1978, 17,860.(c) Uedelhoven, W.; Eberl, IC;Kreissl, F. R. Chem. Ber. 1979, 112,3376.(d) Jeffery, J.C.; Ruiz, M. A.; Stone, F. G. A. J. Orgunomet. Chem. 1988,355,231.
site for initial 0 2 attack, as the oxygen atom of the ketenyl ligand is directly bonded to the W atom. Further evidence comes from the study of the selective 13C0 exchange of 2 under l3C-labe1edcarbon monoxide (95 "C, 3 h). This experiment indicated that the W-CO ligand exhibits an exchange rate 2-6 times faster than that observed for other Os-CO ligands and implied that the W atom is more susceptible to direct chemical attack. Finally, we speculate that the production of a ketenyl fragment is a consequence of the W=C doublebond character of the acetylide ligand in 2. In the absence of this unusual W=C bonding, the oxidation would give rise to an energetically more favorable bridging W=O Os functional group or terminal W=O unit. This type of bonding was clearly noted in the oxoacetylide compound Cp*WReZ(CO)s(O)(CCPh),generated by the treatment of its precursor Cp*WRe2(CO)g(CCPh) with the oxidants 0 2 or NzO.~O
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Acknowledgment. We thank the National Science Council of the Republic of China for support (Grant No. NSC 84-2113-M007-020). Supplementary Material Available: Tables of crystal data, bond distances, atomic coordinates, and anisotropic thermal parameters for 2 and 3 and an ORTEP diagram including selective bond distances for 4 (9 pages). Ordering information is given on any current masthead page. OM950034T (20)Chi, Y.;Cheng, P.-S.; Wu, H.-L.; Hwang, D.-K.; Peng, S.-H.; Lee, G.-H. J . Chem. SOC.,Chem. Commun. 1994,1839.
