Organometallics 1995, 14, 4300-4307
4300
Synthesis, Structure, Fluxional Behavior, and Substitution Reaction of the Metal-Metal-Bonded Heterobimetallic Phosphido-Bridged Complex
CpW(C0)2Or-CO)Or-PPh2)Fe(CO)j Shin-Guang Shyu,*$+Shu-Min Hsiao,+>f Kuan-Jiuh Lin,' and H.-M Gauf Znstitute of Chemistry, Academia Sinica, Taipei, Taiwan 11529, Republic of China, and Department of Chemistry, National Chung Hsing University, Taichung, Taiwan, Republic of China Received April 25, 1995@ The heterobimetallic phosphido-bridged complexes C ~ W ( C O ) ~ ( ~ - C O ) ( C I - P P ~ ~ )(4) F~(CO)~ and CpW(C0)3(pu-PPh2)Fe(C0)4 (5) were prepared by the reaction of CpW(C0)3PPh2 with Fez(C0)g. Photolysis of 5 produced 4. The structures of 4 and 5 were determined by singlecrystal X-ray diffraction. The W-Fe distance was 2.8308(22) A in 4, indicative of a W-Fe bond. The long distance between W and Fe (4.2434(20) A) in 5 indicates no metal-metal bond in the complex. Fluxional behavior involving the exchange of all CO ligands in 4 was studied by variable-temperature 13CNMR spectroscopy. Reaction between 4 and Lewis bases
-
I
L (L = P(OMe)3, PMe3, PPhzH, PPh3, PEt3) a t ambient temperatures produced CpW(C0k(p-PPhz)Fe(CO)a(L)(6) with L regiospecifically coordinated to Fe. However, 5 did not react
(6c) with L under similar conditions. The structure of CpW(CO)z(p-PPhdFe(C0)3(PPh2H) was determined by single-crystal X-ray diffraction.
Systematic investigations on the influence of a metal on the chemistry of its adjacent metal in bimetallic An interesting cooperativity effect between metals in complexes could be of importance for an understanding bimetallic phosphido-bridgedcomplexes is that a metal of the cooperativity effect in binuclear complexes and can activate the substitution reaction of the adjacent clusters. One way is by using different kinds of metal metal carbonyl through the formation of a metal-metal fragments and comparing their influences on a similar b0nd.l Thus, metal-metal bonds in the heterobimetalmetal moiety as in the cases of complexes 2 and 3. The lie phosphido-bridged complexesCpW(CO)2@i-PPha)Mo- other way is by using similar metal fragments and studing their influences on different kinds of metal (COI5(1) and CPF~(CO)(~-CO)(~-PP~~)W(CO)~~ (2)acmoieties. Since the CpW(CO)2 fragment can activate tivate the Mo carbonyl ligand and the W carbonyl the substitution of its adjacent group VI element (Mo ligands correspondingly toward substitution by Lewis or W) carbonyl ligands in complexes 1 and 2,it would bases L (L = PMe3, PPh2H, P(OMe13) at ambient be of interest to see whether the activation can be temperatures via the opening of the metal-metal bond extended to group VI11 elements. to produce CpW(CO)3@i-PPhz)Mo(CO)4L and CpFe(C0)zThe complex CpW(C0)2(p-CO)(p-PPh2)Fe(C0)33 (4) (p-PPh2)W(C0)4Lwith the intramolecular transfer of was chosen as our target of study on the basis of the one Mo carbonyl or one W carbonyl, respectively, to the following three reasons. First, substitution of the adjacent metal.laS2 For the complex CpW(CO)zcu-PPh2)Wsecond carbonyl ligand by phosphine in Fe(COhPR3 (CO)5(3),similar activation of the carbonyl ligands on requires high temperature or a long period of UV the W(C0)s moiety toward substitution by Lewis bases i r r a d i a t i ~ n .If~ we consider that the metallophosphine L by the adjacent W through the metal-metal bond was CpW(C0)2PPh2 is a ligand similar to PR3, it would be also observed a t a higher reaction temperature to of interest to see whether CpW(CO)2 can activate the substitution of the carbonyl ligands on Fe in this produce CpW(C0)2(p-PPh2)W(CO)4L.1b complex. Second, a single-crystal X-ray study of this complex revealed the presence of a bridging carbonyl Academia Sinica. National Chung Hsing University. ligand. This indicates CpW(C0h has a strong interaca Abstract published in Advance ACS Abstracts, August 1, 1995. tion with the adjacent Fe carbonyl. This interaction i l l (a) Shyu, S.-G.; Hsu, J.-Y.; Lin, P.-J.; Wu, W.-J.; Peng, S. M.; may facilitate the substitution of the Fe carbonyl ligand Lee, G. H.; Wen, Y . 3 . Organometallics 1994,13, 1699. (b) Shyu, S.G.; Wu, W.-J.; Peng, S. M.; Lee, G. H.; Wen, Y . 3 . J . Organomet. Chem. such that the substitution can proceed under a relatively 1995,489, 113. (c) Regragui, R.; Dixneuf, P. H.; Taylor, N. J.;Carty, mild conditions.2 Third, its non-metal-metal-bonded A. J. Organometalllics 1986,5, 1. id) Mercer, W. C.; Whittle, R. R.;
Introduction
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-
Burkhardt, E. W.; Geoffroy, G. L. Organometallics 1985,4 , 68. (el Powell, J.;Sawyer, J. F.; Stainer, M. V. R. Inorg. Chem. 1989,28,4461. (D Powell, J.; Coutoure, C.; Gregg, M. R. J . Chem. SOC.,Chem. Commun. 1988,1208. (2)Shyu, S.-G.; Lin, P.-J.; Lin, K.-J.; Wen, Y.-S.; Chang, M.-C. Organometallics 1995,14, 2253. ~~
( 3 ) Linder, E.; Heckmann, M.; Fawzi, R.; Hiller, W. Chem. Ber. 1991, 124, 2171. (41(a1 Clifford, A. F.; Mukherjee, A. K. Inorg. Chem. 1963,2,151. (b)Lewis, J.; Nyholm, R. S.; Sandhu, S. S.; Stiddard, M. H. B. J . Chem. SOC.1964,2825.
0 1995 American Chemical Society
A W-Fe-Bonded Phosphido-Bridged Complex
Organometallics, Vol. 14, No. 9, 1995 4301
Table 1. Spectroscopic Data for 4-6" complex 4 5
6a 6b 6c 6d 6eh
31P{'H} NMR,bcb 93.27 (s,J p - w 257.6)
'H NMR,bsdb
5.41 (s, 5H) 5.14 (6, 5H), 3.62 (d, 3 J p - ~12.0, 9H)
IR, v(C0); cm-l 2072 m, 2041 s, 1977 s, 1925 s, 1851 m, 1736 m 2040 s, 2023 8,1943 s, 1911 s 2034 w, 1962 s, 1913 s, 1837 s
5.02 (s, 5H), 1.64 (d, 2 J ~ 10.0,9H) - ~
2011 m, 1947 s, 1901 s, 1827 s
4.82 (s, 5H)
2025 w, 1958 m, 1905 s, 1832 s
5.28 (s, 5H)
2004 m, 1946 s, 1912 s, 1838s
5.03 (s, 5H), 1.94 (m, 6H), 1.14 (m, 9H)
2003 w, 1941 s, 1904 s, 1834 m
5.16 (s, 5H)
-10.41 (s,J p - w 130.79) 127.19 (d, 2Jp-p 19.93, J p - w 317.77, p-PPhz), 170.46 (d, P(OMe)3) 127.53 (d, V p - p 20.25, JP-w 322.03, pu-PPhz), 16.91 (d, PMe3) 132.43 (d, 'Jp-p 21.80, JP-w 324.76, p-PPhd, 41.22 (d, J p - H 382.71, PPh2H) 129.13 (d, 2 J p - p 10.57; JP-w 309.53, p-PPhd, 62.19 (d, PPh3) 125.93 (d, 'Jp-p 15.67, JP-w 317.71, p-PPh21, 46.83 (d, PEt3)
At room temperature. J values in Hz. In THF solution unless otherwise indicated. In CDC13 solution unless otherwise indicated. Cp, Me, and H groups only. Abbreviations: s, singlet; d, doublet. e In THF solution unless otherwise indicated. Abbreviations: vs, very strong; s, strong; m, medium; w, weak; br, broad; sh, shoulder.
Scheme 1
analogue CpW(C0)3&-PPh2)Fe(C0)4(5) can be prepared and serves as a standard for comparison of their reactivities to reveal the influence of the metal-metal bond in 4. The heterobimetallic phosphido-bridgedcomplexes 4 (with a metal-metal bond) and 5 (without a metalmetal bond) were synthesized. Reactions between 4 and Lewis bases L (L = P(OMe13,PMe3, PPhzH, PPh3, PEt3)
Ph2
U
L
produced CpW(C0)2&-PPhz)Fe(C0)3L(6) with L regiospecifically coordinated to Fe under mild conditions. However, 5 did not react with L under similar conditions. This indicates that CpW(CO)2in 4 could enhance substitution of the adjacent Fe carbonyl through the formation of the metal-metal bond. Reported herein are the synthesis, structures, fluxional behavior, and reactivity studies of 4 and 5. Scheme 1shows reactions that comprise the main focus of our work. The products of the substitution reaction have been characterized
1
I
PPh2)Fe(CO)3(PPh2H) (6c) was also determined by a single-crystal X-ray diffraction study. Experimental Section
Unless otherwise stated, all reactions and manipulations of air-sensitive compounds were carried out at ambient temperatures under an atmosphere of purified N2 with standard procedures. A 450-W Hanovia medium-pressure quartz mercury-vapor lamp (Ace Glass) and a F'yrex Schlenk tube as a reaction vessel were used in the photoreactions. Infrared (IR) spectra were recorded on a Perkin-Elmer 882 infrared spectrophotometer. 'H, 13C,and 31PNMR spectra were measured by using Bruker AMX-500, MSL-200, AC-200, and AC-300 spectrometers. 31PNMR shifts are referenced to 85% H3P04. Except as noted, NMR spectra were collected at room temperature. Electron impact (EI) and fast-atom bombardment ( F B I mass spectra were recorded on a VG 70-2508 or a JEOL JMS-HX 110 mass spectrometer. Microanalyses were performed at the Microanalytic Laboratory at National Cheng Kung University, Tainan, Taiwan, and at Academia Sinica. Spectroscopic data (31Pand 'H NMR and IR) of all new complexes are listed in Table 1. Materials. THF was distilled from potassium and benzophenone under an atmosphere of N2 immediately before use. Other solvents were purified according to established procedures.5 Metal carbonyls (W(CO16, Fe(C0)5), PPh2C1, PMe3, PPhZH, PEt3, and PPh3 were obtained from Strem, P(OMe)3
6a, L = 6b,L= 6 ~L ,= 6d. L = 6e, L =
P(OMe)3 PMe3 PPh2H PPhp PEt3
Ph2 0 P C
/ \ I /co
I
spectroscopically, and the structure of CpW(CO)2@-
5
4
L
- I
&/
L'
J
8
6
was obtained from Merck, and 13C0 (99 atom % 13C) was obtained from Isotec. Other reagents and solvents were obtained from various commercial sources and used as received. Na[CpW(C0)31,6WCp(C0)3PPh2,' and Fe2(C0)s8were prepared by literature procedures.
Synthesis of CpW(CO)&-CO)(p-PPh2)Fe(C0)3 (4) and CpW(CO)&-PPhz)Fe(CO)4(5). A yellow solution of Na[CpW(C0)31(9.30 g, 26.20 mmol) in 250 mL of THF was cooled to 0 "C. PPh2Cl(4.7 mL, 26.20 mmol) was then added slowly to the above solution. After 1 h, the solution turned orangered. Fez(C0)g (9.56 g, 26.20 mmol) was then added to the above solution. After the solution was stirred overnight, the solvent was removed and the residue was chromatographed on grade I1 A l 2 0 3 . Elution with CHzCl&exane (1:6) afforded three fractions. A trace amount of yellow solid was obtained from the first band and was not identified. The red solid 4 was obtained from the second band which is dark red. Yield: 0.98 g (6%). Anal. Calcd for C23H15FeO6Pw C, 41.95; H, 2.30. Found: C, 41.80; H, 2.04. MS (FAB): M+ mlz 658. The orange solid 5 was obtained from the third band after the solvent was removed. Yield: 9.17 g (53%). Anal. Calcd (6)Bender, R.; Braunstein, P.; Jud, J.-M.;Dusausoy, Y. Inorg. Chem. 1983,22, 3394. (7) (a)Adams, H.; Bailey, N. A,; Day, A. N.; Morris, M. J.;Harrison, M. M. J . Organomet. Chem. 1991, 407, 247.(b) Malisch, W.; Maisch, R.; Colquhoun, I. J.; Mcfarlane, W. J . Organomet. Chem. 1981, 220, n r LL.
( 5 )Perrin, D. D.; Armarego, W. L. F.; Perrin, D. R. Purification of Laboratory Chemicals; Pergamon: Oxford, U.K., 1966.
(8) Eisch, J. J.; King, R. B. Organometallic Syntheszs; Academic Press: New York, 1965.
4302 Organometallics, Vol. 14,No. 9, 1995
Shyu et al.
Reaction of 5 with PR3 (R = Ph, OMe, Me) and PPhZH. To a yellow solution containing 250 mg (0.36 mmol) of 5 in 20 mL of THF was added 100 pL (0.84 mmol) of P(OMe13. The solution was stirred in the dark a t reflux temperature overnight. No color change was observed. Results of the 31PNMR study of the reaction mixture indicated the existence of the unreacted 5 and P(OMe)3 and small amounts of unidentified impurities. Similar reaction conditions were applied to the reaction between 5 and PPh3 (reflux for 18 h), PMe3 (ambient temperature overnight), and PPhzH (reflux for 33 h). No complex 6 was observed in the reaction product according to 31PNMR spectra of the reaction mixtures. Reaction between 4 and CO. A solution of 4 (0.20 g, 0.30 Synthesisof CpW(CO)z@-PPhz)Fe(CO)3(P(OMe)3) (6a). mmol) in 25 mL of THF in a 100 mL Schlenk flask was stirred To a red solution of 4 (0.20 g, 0.30 mmol) in 30 mL of THF under 1atm of CO overnight at room temperature. A 31PNMR was added 280 pL of P(OMe)3(2.40 mmol) under NZat ambient study of the solution indicated that no reaction took place temperature. After the mixture was stirred overnight, the between 4 and CO. solvent was removed. The residue was chromatographed on Preparation of 13CO-Enriched4. A solution of 4 (0.60 grade I1 A1203 and eluted with CHzClz/hexane (1:3) to afford 0.91 mmol) in 12 mL of THF in a 50 mL Pyrex Schlenk flask g, two fractions. A trace amount of pink solid was obtained from was irradiated with W light under 1atm of 13C0for 2 h. Only the first band and was not identified. The second band was 4 was observed in the 31PNMR spectrum of the solution. red. After the solvent was removed, 6a was obtained as a red Structure Determination of 4, 5, and 6c. Crystals of solid. Yield: 0.11 g (49%). Anal. Calcd for C25H24FeOsPzW: complexes 4,5, and 6c were grown by slow diffusion of hexanes C, 39.84; H, 3.08. Found: C, 39.84; H, 3.30. MS (FAB):Mf into the saturated solutions of the relevant complexes in CHzmlz 752. Clz a t -15 "C. Suitable single crystals were chosen for indexing on an Enraf-Nonius CAD4 diffi-actometer with graphSynthesisof CpW(C0)2@-PPhz)Fe(CO)a(PMe3)(6b). To a red solution of 4 (0.20 g, 0.30 mmol) in 30 mL of THF was ite-monochromated Mo K a radiation (1 = 0.710 69 A). The unit cell parameters and orientation matrix were established added 0.30 mL (1.19 M in THF, 0.36 mmol) of PMe3 under NZ from a least-squares fit of 25 reflections. Intensity data were a t ambient temperature. After the mixture was stirred collected in the w-20 scanning mode with three standard ovenight, the solvent was removed. The residue was chromatographed on grade I1 A1203 and eluted with CHzClfiexane reflections monitored for intensity variation throughout the (1:4) to afford two fractions. The first band was unreacted 4. experiment. No significant variation in standards was observed, and crystal absorption was empirically corrected for The second band was red. After the solvent was removed, 6b was obtained as a red solid. Yield: 0.125 g (58%). Anal. Calcd using y7-scan through 360" for selected reflections with x near for CzjH24FeOsPzW: C, 42.53; H, 3.43. Found: C, 42.27; H, 90". For complexes 4 and 6c, their structures were solved by 3.38. MS (FAB): M - CO+ mlz 705. direct methods, and E-maps from the starting set with the highest combined figure of merit revealed coordinates for W Synthesis of C~W(CO)Z@-PP~~)F~(CO)~(PP~~H) (6c). and Fe atoms. For 5, the coordinates of W and Fe were To a red solution of 4 (0.20 g, 0.30 mmol) in 25 mL of THF obtained from Patterson syntheses. The remaining non-H was added 100 pL of PPh2H (0.57 mmol) under Nz a t ambient atoms were located from the successive difference Fourier map. temperature. After the mixture was stirred overnight, the The hydrogen atoms in 6c (P-H) were located from its solvent was removed. The residue was chromatographed on difference Fourier maps as well. The chirality parameter q grade I1 A1203 and eluted with CHzClfiexane (1:3) to afford was refined with a value of 1.05 for 5, indicating that the two fractions. The first band was unreacted 4. The second crystal was of a single polarity. The final full-matrix leastband was red. After the solvent was removed, 6c was obtained squares refinement on F converged to give the agreement as a red solid. Yield: 0.16 g (63%). Anal. Calcd for C34H20values R = 0.034, 0.023, and 0.022 for 4, 5, and 6c, respecFeOSPzW: C, 50.03; H, 3.21. Found: C, 49.61; H, 3.24. MS tively. The details of the crystal data and refinements are (FAB): Mfmiz 816. summarized in Table 2. The final positional parameters are listed in Tables 3 (41, 4 (51, and 5 (6c). Selected interatomic Synthesisof CPW(CO)~@-PP~~)F~(CO)~(PP~~) (6d). To distances and bond angles are given in Tables 6 ( 4 and 5) and a red solution of 4 (0.18 g, 0.27 mmol) in 30 mL of THF was 7 (612). All data reduction and refinements were carried out added 72 mg (0.27 mmol) of PPh3 under Nz a t ambient on a MicroVax3600 computer using NRCVAXg programs. temperature. The mixture was stirred for 41 h. After the solvent was removed, a red solid which is a mixture of 4 and 6d was obtained. Complex 4 was removed by washing the Results and Discussion mixture with 30 mL of CHsClfiexane (2:3) solution. Complex 6d was obtained as a red solid. Yield: 0.18 g (74%). Anal. Synthesis, Spectroscopic Characterization, and Calcd for C40H30FeOsPzW: C, 53.90; H, 3.28. Found: C, 53.51; Molecular Structures of 4 and 5. Complex 4 was H, 3.01. MS (FAB): M+ mlz 891. first prepared by the reaction between Li2[CpW(C0)2for C24H15Fe07PW: C, 42.02; H, 2.20. Found: C, 42.29; H, 2.56. MS (FAB): M+ mlz 686. Photolysis of 5. A solution of 5 (1.80 g, 2.62 mmol) in 40 mL of THF was irradiated with W under Nz for 3 h. The color of the solution changed from orange to dark red. The solvent was then removed, and the residue was chromatographed on grade I1 A1203. Elution with CHzClfiexane (1:6) afforded four fractions. Only trace amounts of products were obtained from the first and second bands which were yellow and pink, respectively. They were not identified. The fourth fraction is unreacted 5 (0.16 g, 9%). After the solvent was removed from the third band, 4 was obtained as a red solid. Yield: 1.00 g (58%).
-
Synthesis of CpWT(CO)z@-PPhz)Fe(CO)3(PEts)(6e). To a red solution of 4 (0.21 g, 0.32 mmol) in 30 mL of THF was added 0.35 mL (1.37 M, 0.48 mmol) of PEt3 under NZ a t ambient temperature. The mixture was stirred overnight. The solvent was removed. The residue was chromatographed on grade I1 A1203 and eluted with CHzClfiexane (1%) to afford three fractions. Trace amounts of products were obtained from the first band and the second band. They were not identified. After the solvent was removed, the red solid 6e was obtained from the third band. Yield: 0.167 g (69%). Anal. Calcd for C,~44.95; C~~H~OF~O P ~ WH,: 4.04. Found: C, 44.75; H, 4.04. MS (FAB): Mfm h 748.
PPhzI and Fe(C0hB1-2.~We synthesized the W-Fe complexes 4 and 5 by the reaction of CpW(C0)8PPhZ with Fez(C0)g. r
Photolvsis of 5 with U V Droduced 4. Unlike CDFe(CO)@CO)@-PPh2)W(C0)4 (2),1°4 did not react with CO to open the metal-metal bond t o reproduce 5. The
(9) Gabe, E. J.; Lepage, Y.; Charland, J.-P.; Lee, F. L.; White, P. S. J . Appl. Crystallogr. 1989, 22, 384. (10)Shyu, S.-G.; Lin, P.-J.; Wen, Y.-S. J . Organomet. Chem. 1993,
443, 115.
A W-Fe-Bonded Phosphido-Bridged Complex
Organometallics, Vol. 14, No. 9, 1995 4303
Table 2. Cwstal and Intensity Collection Data for 4.5, and f3c 4 mol formula mol wt space group
a (A) b c (A)
(4)
P (de&
v (A31
Q(ca1cd)(Mg m-3) Z cryst dimens ( m m ) abs coeff p(Mo Ka)(mm-l) temp radiation A(Mo Ka)(A) 20 range (deg) scan type no. of unique rflns no. of obsd rflns variables
C24H15Fe07PW
C34H26Fe05Pz
658.03 P2 1Ic 10.5270(11 12.3458(12) 17.544(3) 99.080(10) 2251.6(5) 1.941 4 0.06 x 0.05 x 0.15 5.89
686.04 Pca21 16.613(4) 9.0392(10) 15.910(4) 90 2389.2(9) 1.907 4 0.15 x 0.25 x 0.15 5.70
816.22 P2 lln 13.909(2) 10.888(2) 19.973(3) 92.598( 11 3021.6(9) 1.794 4 0.12 x 0.31 x 0.26 4.51
room temp
room temp
room temp
0.710 69
0.710 69 45 W-28 1634 1368 (>2.0u(Z)) 308 0.023 0.022 1.21 C0.750 0.007
0.710 69 45 w-20 3938 3173 (>2.5dl)) 308 0.022 0.023 1.27
45
AF ( e1.43)
0-28 2940 1774 (>2.00(Z)) 290 0.034 0.031 1.13
