Organometallics 1983, 2, 165-167
hydrosilylation-dehydrogenation reaction of a-olefins with silicon hydrides to give vinylic and allylic silanes as well as for normal hydrosilylation reactions. The corresponding iridium complex [(C5Me51r)2C14] (lb)2was, however, quite inactive for either reaction though it did promote the addition of Si-H to alkyne^.^ The lack of reactivity of other iridium complexes in olefin hydrosilylation has previously been noted.4 Separate experiments showed that the isomerization of 1-hexene was only very slowly catalyzed by l b and EkSiH and that rapid formation of internal hexene isomers was not the reason why l b was a poor catalyst. Under conditions reasonably similar to those used in the hydrosilylation reactions (CH2C12solvent, 20 "C) l b reacted directly and quickly with Et3SiH to give a new colorless complex (70% yield) that was shown to be the iridium(V) silyl hydride [C5Me51r(H)2C1(SiEt3)] (3)5 [IR v(1r-H) 2135, v(1r-Cl, terminal) 305 cm-'; lH NMR (CD2C1,) 6 -12.6 (s, IrHJ, 0.8 (4, J = 7.5 Hz, SiCH2),0.94 (t, J = 7.5 Hz, SiCH2CH3),1.91 (8, C5Me5)]. Extended reaction converted 3 into [C5Me51r(H)2(SiEt3)2] (415that was more conveniently prepared by reaction of l b (30% yield) or 2 (40% yield) with Et3SiH in the presence of triethylamine in refluxing benzene. [IR u(1r-H) 2160 cm-l; mass spectrum, m / e 556,558 (M - 1)'; 'H NMR (CDCl,) 6 -17.4 (s, IrHJ, 0.67 (9, J = 8 Hz, SiCH,), 0.82 (t, J = 8 Hz, SiCH,CH3), 1.97 (s, C5Me5)].
lb
2
H
H
s\'
I Et 3
\C 'l
H
H
4
3
Complex 4 is the analogue of the rhodium(V) complex [C5Me5Rh(H)2(SiEt3)2] that we recently reported,6 and X-ray photographs show them to be isomorphous. Although a number of iridium(V) hydrides LzIrH,7 and one iridium(V) organometallic C5Me51rMe48have been prepared, 3 and 4 are the first organosilyls in this oxidation state. In fact even some Ir(1) complexes only add R3Si-H with relu~tance.~ We are investigating details of these and related reactions further, but we note (a) that the dinuclear dihydride complex 21° is intermediate" in the reaction of lb to give (2)For a review of these complexes, see Maitlis, P. M. Chem. Soc. Reo. 1981,10, 1. (3)Millan, A. Ph.D. Thesis, University of Sheffield, 1981. (4)Haszeldine, R. N.;Parish, R. V.; Parry, D. J. J. Chem. Soc. A 1969, 683. (5)Satisfactory microanalyses were obtained for all new complexes. (6)Fernandez, M.-J.; Maitlis, P. M. J. Chem. Soc., Chem. Commun. 1982,310. (7) Mann, B. E.; Masters, C.; Shaw, B. L.J . Inorg. Nucl. Chem. 1971, 33,2195. (8)Isobe, K.; Bailey, P. M.; Maitlis, P. M. J. Chem. Soc., Chem. Commun. 1981,808. but see (9)Chalk, A.J.; Harrod, J. F. J. Am. Chem. SOC.1965,87,16, Blackburn, S. N.; Haszeldine, R. N.; Parish, R. V.; Setchfield, J. H. J. Chem. Res., Synop. 1980,170. (10)Gill, D. S.;Maitlis, P. M. J. Organomet. Chem. 1975,87,359. (11)The dihydride 2 is unique amongst C5Me5-Ir complexes in being deep blue. We have therefore interpreted the transient blue color seen during reaction of lb with EbSiH &evidence that 2 is the intermediate. This is, of course, supported by the direct reaction of 2 to give 3.
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3 and (b) that 2 reacts directly with Et3SiH to give 3. This latter reaction is, formally at least, an example of the rather rare oxidative addition Ir(II1) Ir(V) (d6 d4).
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-
Acknowledgment. We thank the SERC for supporting this work, Johnson Matthey Ltd for the loan of iridium salts, and Dr. P. M. Bailey for the X-ray measurement. Metal-Metal Multlple Bonds In Ratlonal Cluster Synthesis.' Novel Isomerlsm In Iron-Molybdenum-Sulfur Clusters and a Molybdenum-Sulfur Cubane. Structure of (175-CH,C,H,)2M02Fe2(ll~-S)2(CO),(ll-CO)2 P. Douglas Williams, M. David Curtis,' D. Neil Duffy, and Wllllam M. Butler Department of Chemistry, The University of Michigan Ann Arbor, Michigan 48109 Received June 28, 1982
Summary: Reaction of R,Mo,(CO),(Mo=Mo), R = Cp, Cp', or v5-CH3C5H, (l), with Fe,S2(CO), generates a pair of isomeric iron-molybdenum-sulfur clusters with different Fe2Mo,S2 frameworks. Although both isomers have a 62-cluster-electroncount, different formal oxidation states must be assigned to the metals in order for them to achieve an 18-electron count. Also, the Mo=Mo bond of 1 displaces propylene from Cp,Mo,(SC,H,S), to give the cluster Cp,Cp',Mo,S,. These reactions demonstrate the utility of the MoEMo triple bond in the rational synthesis of metal-sulfur clusters.
Interest in metal sulfides has resulted in part from their importance as catalysts.2 Iron-molybdenumsulfur compounds in particular are interesting as possible models of hydrodesulfurization catalysts3s4and the nitrogenase cof a ~ t o r . Here ~ we report a rational approach to the synthesis of molybdenum-sulfur clusters and an unprecedented system of isomeric iron-molybdenum-sulfur clusters. The utility of sulfur ligands in the stabilization of metal clusters has already been demonstrated.6 Of particular utility in the preparation of iron-sulfur clusters is the compound Fe2S2(CO),which has been shown to react with a variety of metal carbonyls and low-valent metal comp1exes.'-l3 (1)Part 11 of Metal-Metal Multiple Bonds. Part 10: Curtis, M. D.; Fotinos, N. A.; Han, K. R.; Butler, W. M. J . A m . Chem. Soc., in press. (2)Mitchell, P. C. H. Catalysis (London) 1977,1,204-233. (3)Furimsky, E. Catal. Rev.-Sci. Eng. 1980,22, 371. (4)(a) DuBois, M. R.; Haltiwanger, R. C.; Miller, D. J.; Glatzmaier, G. J . Am. Chem. SOC.1979,101,5245.(b) DuBois, M. R.; VanDerveer, M. C.; DuBois, D. L.; Haltiwanger, R. C.; Miller, W. K. Ibid. 1980,102, 7456. (5)(a) Coucouvanis, D. Acc. Chem. Res. 1981,14,20. (b) Muller, A.; Diemann, E.; Jostes, R.; Bogge, H. Angew. Chem., Int. Ed. Engl. 1981, 20, 934. (6)Vahrenkamp, H.Angew. Chem., Int. Ed. Engl. 1975,14,322. (7) Khattab, S.A.;Marko, L.;Bor, G.; Marko, B. J. Organomet. Chem. 1964,1 , 373. (8)Seyferth, D.; Henderson, R. S.; Gallagher, M. K. J. Organomet. Chem. 1980,193, C75. (9)Braunstein, P.; Sappa, E.; Tiripicchio, A.; Camellini, M. T. Inorg. Chim. Acta 1980,45,L191. (10)Vahrenkamp, H.; Wucherer, E. J. Angew. Chem., Int. Ed. Engl. 1981.20. 680. (11, Seyferth, D.; Henderson, R. S.; Fackler, J. D., Jr.; Majany, A. M. J . Organomet. Chem. 1981,213,C21. (12)Braunstein, P.;Tiripicchio, Camellini, M. T.; Sappa, E. Inorg. Chem. 1981,20,3586. (13)Day, V. W.; Leach, D. A.; Rauchfuss, T . B. J . Am. Chem. Soc. 1982,104,1290. ~
0 1983 American Chemical Society
166 Organometallics, Vol. 2, No. 1, 1983
Communications
Table I. Important Bond Lengths ( A ) and Angles (deg) in 3b and 4aY 4a
3b Ma-Mo' Mo-Fe Mo-Fe'
2.821 (1) 2.776 (1) 2.805 (1)
Mo-Mo' Mo-Fe Mo-Fe'
2.846 (5) 2.818 (5) 2.815 (5)
Mo-S
Fe-S'
2.344 (1) 2.381 (1) 2.213 ( 2 )
Mo-S Mo-S' Fe-S
2.335 (9) 2.327 ( 9 ) 2.165 (8)
Mo-C(u) Fe-C(pj
2.025 ( 6 ) 2.270 i6j
Mo-Cru) Fez-C(;j
2.357 (12)
Fe'-%) Fe-Mo-Fe' Fe-Mo-Mo'
1.90 ( 4 ) 2.62 i 3 j 2.64 (3)
Mo-S
CP'
Mo-C(ring),,
Figure 1. Molecular structure of Cp2MozFeZ(~-S)2(CO)6(rr,-C0)2Fe-Mo-Ma' (4a) (Fe-Fe distance is nonbonding). Fe-Mo'-Mo
The reactive site afforded by multiple metal-metal bonds has also been useful in the synthesis of new metal cluster complexes.1p16 Since the M e M o triple bond in CpzMo2(CO),(la) has been shown to add organic disulfides,'8 and since Seyferth et al." have elegantly demonstrated the similarity of the reactivity of the S S bonds in Fe,S,(CO), (2) and organic disulfides, it seemed highly likely that a combination of these approaches would allow for a rational cluster synthesis. In fact, 1 and 2 react completely at room temperature in less than 0.5 h to give essentially quantitative yields of MozFezSzclusters according to the stoichiometry of eq 1 (toluene solvent). The Cp' complexes are somewhat more soluble than the uusubstituted, Cp complexes.
+
60.14 (3) 59.14 (3)
Ma-S'-Mo Fe-S'-Mo Fe-S'-Mo'
73.30 (4) 75.00 ( 5 ) 75.14 (5)
Mo-C-0
152.24 (50)
a
Fe-Mo'-Mo Mo-S-Mo' Fe-S-Mo
85.8 (1) 59.6 ( 1 ) 59.7 (1)
Fe-S-Mo'
75.3 (3) 77.4 (3) 77.5 (3)
Mo-C-0 Fe-C-0 Fe-CO-0
159(3) 119 (2) 116 (2)
Lengths a n d angles f o r 4a f o u n d in ref 20.
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2&MoZ(CO),(Mo=Mo) Fe+3z(C0)6 la, R = Cp lb, R = Cp' or n6-CH,C,H,
column with CHzClzas the eluent. While this work was in progress, Braunstein and co-workers published the synthesis and structure of complex 4a.M This complex was shown to possess the butterfly geometry expected for a 62-electron cluster.21 The structure of 48 is depicted in Figure 1,and pertinent bond distances and angles are given in Table I. The second cluster, 3, has been shown to he a centrosymmetric isomer of 4 with a planar MozFez skeleton (Figure 2).22"4 Although butterfly clusters have been (14) Curtis. M. D.; Messerle, L.; Fqtinas, N. A,; Gerlach, R. F. In 'Reactimty of Metal-Metal Bands", Chisholm, M.H., Ed.; Waahington: D.C., 1981; ACS 8ymp. Ser. No. 155, pp 221-258. (15) Chisholm, M. H.; Erringon, R. J., Folting, K.;Huffman, J. C. J. Am. Chem. SOC.1982,104,2025. (16) Curtis, M. D.; Butler, W.M. J. Chem. Soe., Chem. Commun. 1980, 99s
(17) Mffiinnis, R. N.; Ryan,T. R;MeCarley, R E.J. Am. Chem. Soe. 1978,100,7900. (18) Curtis, M. D.; Klingler, R.J. J. Orgonomet. C k m . l978,161,23. (19) Seyferth, D.; Henderson, R. S.;Song, L.-C. Orgammotallies 1982, 1, 125. (20) Brawtein, P.; Jud, J. M.; Tiripiechio, A,; Tiripinhio-Camelhi, M.; Sappa, E. Angew. Chem., Int. Ed. Engl. 1982.21.307. (21) Lauher, J. W. J. Am. Chem. Soe. 1978.100.5305 and references therein
shown to exhibit a range of fold angles and bond distances, depending on the electron planar 62-electron clusters are exceedingly rare?7 Only two other planar, mixed-metal M, clusters are known: M O ~ M ~ ( C O(M )~L~ = Pd, Pt;L = Et,P)?8 With M = Pd or Pt, these 58(231 Cp',MqFe,(rrrSI~(CO16CI,-COJ*(4b): mp 222 O C ; IR (KB4 2040 (m),2005 (9). 1975 (81,1955 Imi. IY40 I d , 1795 (SIem-','H N M R ICDCI,. d 7.241 2.15 16 tl), 5.10 t8 HJ. Anal. Calcd for (C,H,.Fe,.Mo,O,S,I. C, 32.03 H. 1.88: Fe., 14.89 S~, ~ Mo.~25.68: ~~, ,. 855. . ~Found:~t'. ;>Z.Ufi ~ H.1.95: . Fe, I5.8i; Mi, 25.20: S, 8.74. Our unit cell data for 48 agrees within experimental error with those reported in ref 20. (24) Dark brown crystals of 3b were obtained from CH,C12/herane. All measurements were performed on a Syntex P2, four-circle diffraetometer at ambient temperature with graphite-filtered Mo Ka radiation. J b crystallizes in the triclinic space group Pi, 2 = 1, (I = 9.219 (2) A, b = 6.899 (2) A, c = 10.441 (2) A, (I = 73.34 (2)O, 8 = 113.68 (Z)', y = 95.98 (Z)', V = 582.5 (3) A3, p= 2.14 g/cm8, and pow = 2.12 g/cm3 (flotation). The prismatic crystal had the dimensions 0.221 x 0.184 x 0.191 mm. The heavy atoms were located by direct methods (MULTAN) and light atom8 were located in subsequent difference maps. The structure waa refined to least-squares, anisotropic convergence on ell nonhydrogen atoms using 2357 reflections with I > 3dO; final R value was 0.047 and the weighted R value WBS 0.063.A deaeription of the computing pmgrams used can be found in ref 25. The standard reduced cell has the values a, b, e, a,8, and y = 6.899A.9.219 A, 10.441 A, 66.32'. 73.34'. and 94.02', respectively. (25) Curtis, M. D.; Green,J.; Butler, W. M. J. Organomet. Chem. 1979, 164,371. (26) Carty, A. J.; MacLaughlin, S. A,; Wagner, J. V.: Taylor, N. J. Organometallics 1982, I, 1013. (27) Re+(CO),e% Churchill, M. R.; Bau, R. Inorg. Chem. 1968, 7,2606. ~~
~~
~~~
~
~~~~~
Organometallics 1983,2, 167-169
167
electron clusters are electronically equivalent to the 62Synthesls, Structure, and Spectral Propertles of electron MozFe2clusters described here.21v29 Given the Mo(CO)( RCsR‘)L,X, Complexes range of observed geometries, electron ~ o u n t s , and ’~~~~ isomers within a given electron count,15 it would appear Paul 6. Winston, Sharon J. Nleter Burgmayer, and that any attempt to predict structures and stoichiometries L. Templeton’ Joseph of M4 clusters on the basis of any cluster counting scheme should proceed with utmost caution. Department of Chemistry, University of North Carolina Localized electron counting arguments can also be used Chapel Hill, North Carolina 27514 to derive an 18-electronconfiguration at each metal center in complexes 3 and 4;but, rather surprisingly, different Received July 7, 1982 formal oxidation states must be assigned in order to do so. Assuming each M-M bond and each p C 0 contribute one Summary: The preparation of Mo(C0)(R’C=CR2)electron each to the metal, Cp- contributes six, and each (PEtJ2Br2 (R’ = Ph, R2 = H, 1; R’ = R2 = Me, 2) and the M-S and terminal M-CO bond contribute two, then for structure of 1 are reported as the first members of a new 3 we assign oxidation states of S2, Cp-, Fe+l, and Mo+~. Because of the different roles played by the carbonyl class of formal 16-electron Mo(I1) complexes, Mo(C0)bonded to Mo in the two isomers, the formal oxidation (RCrCR)L2X2. The unique NMR chemical shifts of aThese complexes will be states in 4 are FeO and Mo+~.~O donor alkyne ligands have been supplemented by visible the subject of a planned Mossbauer study. spectroscopy and cyclic voltammetry, both convenient A comparison of the M-M and M-S distances in Table probes for studying other electron-deficient complexes I show that the M-M bonds are shorter by 0.02-0.03 A and with a-donor ligands in the coordination sphere. the M-S bonds longer by 0.01-0.05 A, in the butterfly 4a vs. the planar 3b. In both structures, the Mo-Mo bond is surprisingly short compared to the Mo-Fe bond (a Monomeric metal alkyne complexes display a rich difference of about 0.2 A might be expected on the basis chemistry that is inconsistent with an alkyne bonding of atomic radii). Apparently the double sulfide bridge of model which neglects the second alkyne T system.’ the Mo-Mo bond imparts additional bonding character to Communications describing five-coordinateMo(I1) alkyne its orbital m a k e ~ p . ~ ’ complexes,2 structures of alkyne ligands as two- and The generality of the reaction between metal sulfur four-electron donors in closely related complexes ([ Cocomplexes and metal-metal multiple bonds in rational (CzPhz)L3]+ and [ C O ( C ~ P ~ ~ ) L ~ ( C H , Cand N ) ]formation +)~ cluster synthesis is shown by the reaction of 5 with the of a coordinated alkyne from coupling of carbon monoxide M-Mo bond of lb (eq 2). In the formation of the MOqS4 and methylidyne ligands4 have been reported in the first half of 1982 alone. We wish to report here the preparation C~MO(SCH&H(M~)S)~M + OlbC ~ of a new class of alkyne complexes, Mo(CO)(R’C= 5 CP~CP’~MO + ~C3H6 S ~ (2) CR2)L2X2,which hold promise as versatile reagents for 6 expanding the chemistry of group 6 alkyne complexes. A deep blue methylene chloride solution of Mo(CO)*cluster, 6,32the displacement of propylene from 5 by the (PEtJ2Br; with a threefold excess of phenylacetylene was Mo=Mo bonds presumably parallels the analogous disheated at 40 “C for 18 h to yield a dark green-brown soplacement of C3H6by the C=C bonds of acetylene^.^^ lution. Solvent removal and extraction of the residue with Acknowledgment. We thank the National Science diethyl ether produced a light green solution of MoFoundation for support through Grant No. CHE79(CO)(PhC=CH)(PEt3)2Brz(1). Subsequent recrystalli07748-02. P.D.W. thanks the Department of Chemistry zation from ether/toluene yielded analytically pure forest and the donors of the Samuel H. Baer Fellowship for green crystals of 1. An analogous synthesis utilizing a support. We are also grateful to Dr. P. Braunstein for tenfold excess of 2-butyne yielded Mo(CO)(MeC= helpful comments. CMe)(PEtJzBrz (2). Registry No. lb, 83587-35-3;2, 14243-23-3;3b, 83587-36-4; The lH NMR spectrum of 1 revealed a resonance at 13.0 4b, 83603-89-8;5, 81423-61-2;6,83587-37-5; Mo, 7439-98-7;Fe, ppm which was assigned to the acetylenic proton in accord 7439-89-6. with previous NMR observations for six-coordinate terminal (alkyne)molybdenum(II)complexes.6 In conjuncSupplementary Material Available: Tables of fractional tion with the single v(C0) infrared absorption at 1950 coordinates,thermal factor, and observed and calculated structure cm-’ and molecular orbital guideliness established for d4 factors for 3b (12 pages). Ordering information is given on any
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current masthead page. (28) Bender, R.; Braunstein, P.; Dusausoy, Y.; Protas, J. Angew. Chem., Int. Ed. Engl. 1978,17,596; J.Organomet. Chem. 1979,172, C51. (29) Lauher, J. W. J. Organomet. Chem. 1981,213, 25. (30) In this assignment, it is assumed that the *p3-C0*in 4 contributes two electrons to Ma and none to Fe. This carbonyl is best assigned a role as ‘semibridging” since its 13Cresonance falls a t 238 ppm, well within the range for “terminal” Mo-CO carbonyls. (31) Rives, A. B.; Xiao-Zang, Y.; Fenske, R. F. Inorg. Chem. 1982,21, 2286. (32) Complex 6 is generated by heating of a toluene solution of l b and 5 to 65 “C for 48 h followed by cooling and filtering off the product as a violet powder. 6 decomposes in chlorinated solvents after several hours and is sparingly soluble in most common organic solvents. X-ray structure characterization of this species is planned. Cp2Cp’,Mo,S4 (6): mp ca. 330 OC; ‘H NMR (CDC13, 6 7.24) 2.02 (6 H), 5.11 (8 H), 5.17 (10 H) ppm; mass spectrum, m / e (P)* 800, (P - CH3)+785, (P - CH3C6H4)+721.
0276-7333/83/2302-0167$01.50/0
(1) Tatsumi, K.; Hoffmann, R.; Templeton, J. L. Inorg. Chem. 1982, 21, 466. (2) (a) Kamata, M.; Yoshida, T.; Otsuka, S.; Hirotsu, K.; Higuchi, T.; Kido, M.; Tatsumi, K.; Hoffmann, R. Organometallics 1982,1,227. (b) The structure of a square-pyramidal molybdenum(I1) alkyne has also been recently communicated by: De Cian, A.; Colin, J.; Schappacher, M.; Ricard, L.; Weiss, R. J. Am. Chem. SOC.1981, 103, 1850. (3) Capelle, B.; Beauchamp, A. L.; Dartiguenave, M.; Dartiguenave, Y. J. Chem. SOC.,Chem. Commun. 1982, 566. (4) Churchill, M. R.; Wasserman, H. J.; Holmes, S. J.; Schrock, R. R. Organometallics 1982, 1, 766. (5) Moss, J. R.; Shaw, B. L. J. Chem. SOC.A 1970, 595. (6) (a) McDonald, J. W.; Newton, W. E.; Creedy, C. T. C.; Corbin, J. L. J . Organomet. Chem. 1975, 92, C25. (b) Templeton, J. L.; Ward, B. C.; Chen, G. J.-J.; McDonald, J. W.; Newton, W. E. Inorg. Chem. 1981, 20, 1248.
0 1983 American Chemical Society
