Using Zirconium Half-Sandwich Complexes as Building Blocks in a

Luke Grocholl, Volker Huch, and Lothar Stahl, Richard J. Staples, Phaedra Steinhart and Alison Johnson. Inorganic Chemistry 1997 36 (20), 4451-4457 ...
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5344

Organometallics 1995, 14, 5344-5349

Using Zirconium Half-Sandwich Complexes as Building Blocks in a New Class of Zr-M Heterobimetallics Containing Unsupported Zr-M Bonds (M = Fe, Ru, Co)? Stefan Friedrich and Lutz H. Gade* Institut fir Anorganische Chemie, Universitat Wiirzburg, Am Hubland, 0-97074 Wurzburg, Germany

Ian J. Scowen and Mary McPartlin School of Chemistry, University of North London, Holloway Road, London N7 8DB, U.K. Received July 24, 1995@

A new class of Zr-M heterobimetallic complexes (M = Fe, Ru, Co) containing the (CHz(CH2NSiMe&(Cp)Zr} fragment as a building block has been synthesized by salt metathesis of CHz(CHzNSiMe3)2(Cp)ZrCl (5) with K[CpM(CO)z] ( M = Fe, Ru) and Na[Co(C0)3(PR3)1(R = Ph, Tol). The zirconium half-sandwich complex 5 was obtained in four reaction steps from ZrCl4 via the spirocyclic complex [CHdCH2NSiMe3)2lzZr (l),the (diamido)dichlorozirconium complex CH2(CHzNSiMe3)zZrClz (2), and its soluble THF-adduct CH,(CHzNSiMe&ZrClZ(THF)z (3). The latter was converted to 5 in good yield by reaction with LiCp. The Zr-Fe heterodinuclear complex CHZ(CHZNS~M~~)Z(C~)Z~-F~(CO)ZC~ (6) has been characterized by X-ray crystal structure analysis which has established the presence of a n unsupported Zr-Fe bond. The v(C0) infrared bands of the CpM(C0)z moieties in the Zr-M complexes (M’ = Fe, Ru) indicate a significant ionic contribution to the Zr-M bonding. Introduction Ever since the first successful syntheses of Zr-Fe and Zr-Ru heterobimetallic complexes in Casey’s group a decade ago1S2there have been several efforts to prepare stable complexes containing unsupported Zr-M bonds (M’ = late transition metal) (type A, Figure l h 3 These are thought to generate two reactive fragments upon cleavage of the metal-metal bond which, as a consequence of their different electronic properties, could then react regioselectively with (and thus activate) functionalized unsaturated hydrocarbons. Whereas the Zr-Ru species studied by Casey and co-workers were sufficiently stable to study their reactivity toward various substrate^,^ all other Z r - M compounds prepared to date proved to be too labile to either fully characterize them or even investigate their chemical behavior. We have recently prepared a series of stable M-M heterobimetallics (M = Fe, Ru, Co; M = Ti, Zr, HD with unsupported M-M bonds in which the early transition metal is stabilized by a tripodal triamido ligand (type B in Figure l).5,6 This has in fact proved to be the key to stabilization of a whole range of such species which has opened up the possiblity of systematic comparative studies. Remarkably, the metal-metal bond in the ’ We dedicate this paper to Professor Max Schmidt on the occasion of his 70th birthday. Abstract published in Advance ACS Abstracts, November I, 1995. (1) (a) Casey, C. P.; Jordan, R. F.; Rheingold, A. L. J. Am. Chem. SOC.1983,105, 665. (b) Casey, C. P.; Jordan, R. F.; Rheingold, A. L. Organometallics 1984,3,504. (c) Casey, C. P. J. Organomet. Chem. 1990,400,205. (2) Review: Stephan, D. W. Coord. Chem. Rev. 1989,95,41. (3) (a) Thiele, K.-H.; Kriiger, C.; Sorkau, A,; btvos, I.; Bartik, T.; Palyi, G. Organometallics 1987,6, 2290. (b) Bartik, T.; Windisch, H.; Sorkau, A.; Thiele, K.-H.; Kriebel, C.; Herfurth, A,; Thoerner, C. M.; Zucchi, C.; Palyi, G. Inorg. Chim. Acta 1994,227,201 and references cited therein. (4) (a) Casey, C. P.; Palermo, R. E.; Jordan, R. F. J.A m . Chem. SOC. 1986,107,4597. (b) Casey, C. P.; Palermo, R. E. J. Am. Chem. SOC. 1986,108,549. @

To I

A

SiMeS

B

C

Figure 1. Zr-M heterobimetallics of types A-C. amido-zirconium-iron and amido-zirconium-ruthenium complexes appears to be significantly less ionic than in Casey’s compounds, a situation which is reflected in the infrared v(C0) spectra. This situation may be interpreted as being a consequence of the greater Lewis acidity of the amido-zirconium fragments in comparison t o the Cp2Zr fragments in the complexes of type A. The M-M bonding electron pair in type B complexes is thus probably more evenly distributed between the two metal centers. In our quest for new types of Zr-M complexes and in order to probe the influence of the set of ligands at the Zr center, we have now attempted the combination of Casey’s approach using CpZr complex fragments as building blocks while simultaneously utilizing the stabilizing effect that a chelating amido ligand has in such systems. To this end we have synthesized a new type of Zr half-sandwich complex which may be used in metathetical condensation reactions with transition metal carbonylates (type CL7 Here we report the synthesis of such “early-late heterobimetallics” and the structural characterization of a Zr-Fe-bonded complex. (5)(a)Friedrich, S.;Memmler, H.; Gade, L. H.; Li, W.-S.; McPartlin, M. Angew. Chem., Int. Ed. Engl. 1994,33, 676. (b) Friedrich, S.; Memmler, H.; Gade, L. H.; Li, W.-S.; Scowen, I.; McPartlin, M.; Housecroft, C. E. Submitted for publication in Inorg. Chem. (6) Findeis, B.; Schubart, M.; Platzek, C.; Gade, L. H.; Scowen, I.; McPartlin, M. Submitted for publication.

0276-7333/95/2314-5344$09.00/00 1995 American Chemical Society

Zr-M Heterobimetallics

Experimental Section All manipulations were performed under a n inert gas atmosphere of dried argon in standard (Schlenk) glassware which was flame dried with a Bunsen burner prior to use. Solvents were dried according to standard procedures and saturated with Ar. The deuterated solvents used for the NMR spectroscopicmeasurements were degassed by three successive "freeze-pump-thaw" cycles and dried over 4-A molecular sieves. The lH-, 29Si-,and 31P-NMRspectra were recorded on a Bruker AC 200 spectrometer equipped with a B-VT-2000 variable-temperature unit (at 200.13, 50.32,39.76, and 81.03 MHz, respectively) with tetramethylsilane and (85%, ext.) as references. Infrared spectra were recorded on PerkinElmer 1420 and Bruker IRS 25 FT-spectrometers. Elemental analyses were carried out in the microanalytical laboratory of the chemistry department at Wurzburg. The amine CH2(CH2NHSiMe& was prepared from the commercially available C H ~ ( C H Z N Has~ )reported ~ in the.literature.8 The salts of the transition metal carbonylates K[CpFe(C0)21, K[CpRu(CO)zl, Na[Co(C0)dPPh3)1, and Na[Co(CO)dPToldl (To1 = 4-CH&6&) were synthesized by literature method^.^ All other chemicals used as starting materials were obtained commercially and used without further purification. (1) Preparation of [CH~(CJ3zNSiMes)21&r(1). To a stirred solution of CH2(CH2NHSiMe& (3.03 g = 13.87 mmol) in 15 mL of toluene, which was cooled at -40 "C, was slowly added 27.75 mmol of nBuLi (11.10 mL of a 2.5 M solution in hexanes). The reaction mixture was warmed t o room temperature and, after the butane evolution had subsided, heated under reflux for a short period of time. After the solution of the lithiated amine had been stirred at room temperature for another 30 min, it was cooled t o -50 "C. Solid Z&l4 (1.56 g = 6.69 mmol) was added, the reaction mixture was warmed to room temperature over a period of 15 h, and the solvent was evaporated in vacuo. The residue was extracted with pentane (50 mL), the extract filtered, and the volume of the solution reduced to ca. 15 mL. Storage at -35 "C yielded [CHz(CHzNSiMe&12Zr (1)as a colorless crystalline solid: yield 3.21 g (88%);mp 85°C dec; IR (KBr) 2950 vs, 2890 vs, 2880 VS, 2830 VS, 2780 m, 2635 W, 1915 VW, 1860 vw,1590 W, 1425 m, 1395 m, 1365 m, 1352 m, 1285 s, 1245 vs, 1090 8,1052 vs, 955 S, 890 VS, 835 VS, 780 S, 742 S, 675 s cm-'; lH NMR (C6D6, 200 MHz) 6 0.24 [s, Si(CHd31, 1.90 (m, CH2), 3.33 (m, CH2N); 13C NMR (C6D6, 50.3 MHz) 6 0.5 [Si(CH&], 39.8 (CHz), 51.5 (CHzN); 29SiNMR (C6D6, 39.8 MHz) 6 -2.6. Anal. Calcd for C18H48N4Si4Zr: C, 41.25; H, 9.23; N, 10.69. Found: C, 41.57; H, 9.12; N, 10.54. (2) Preparation of CHz(CHzNSiMe&ZrCle (2). A suspension of 2.02 g (3.85 mmol) of [CH2(CHzNSiMe3)212Zr(1) and 0.89 g (3.82 mmmol) of ZrCl4 in 15 mL of toluene was heated at 60 "C for 3 d. After evaporation of the solvent in vacuo, the residue was washed with 15 mL of pentane and the colorless solid dried in vacuo: yield 2.23 g (77%); mp 74 "C dec; IR (KBr) 2955 vs, 2900 s, 2865 s, 2000 vw, 1925 vw, 1870 vw,1635 w,1598 w,1568 w,1465 m,1442m,1408 m, 1350 m, 1312 W, 1248 VS, 1223 m, 1188 vw,1082 s, 1040 vs, 935 Vs, 845 VS br, 752 S, 718 VS, 682 S cm-'; 'H NMR (C&, 200 MHz) 6 0.29 [s, Si(CHd31, 1.74 (m, C&), 3.31 (m, CH2N); 13CNMR (C6D6, 50.3 MHz) 6 -0.3 [si(CH3)3], 39.3 (CHz), 52.9 (CH2N); 29SiNMR (C&, 39.8 MHz) 6 0.8. Anal. Calcd for CgH24ClzN2SizZr: C, 28.55; H, 6.39; N, 7.40. Found: C, 28.37; H, 6.21; N, 7.21. (3)Preparation of CHz(CHzNSiMes)aZrClz(THF)2 (3). A solution of 1.03 g (2.72 mmol) of CH2(CH2NSiMe&ZrClz (2) (7) Very recently, the use of {Cp*(NMez)zTi}as a building block in a Ti-Ru heterobimetallic compound has been reported: Galakhov, M.; Martin, A.; Mena, M.; Yelamos, C. J. Organomet. Chem. 1995, 496, 217. (8) Dammgen, U.; Burger, H. 2.Anorg. Allg. Chem. 1977,429, 173. (9)Brookhart, M.; Studabaker, W. B.; Husk, R. Organometallics 1987,6, 1141.

Organometallics, Vol. 14, No. 11, 1995 5345 in 5 mL of THF was stored at -35 "C to yield CHz(CH2NSiMe&ZrClz(THF)z (3)as colorless crystals: yield 1.08 g (76%);mp 98 "C dec; IR (KBr) 2940 vs, 2880 VS, 2850 VS,2820 s, 2690 m, 1995 vw, 1918 vw, 1865 vw, 1685 w, 1458 m, 1415 m, 1402 m, 1365 m, 1348 m, 1285 m, 1245 vs, 1190 w, 1175 W, 1095 9, 1030 VS, 10109, 940 VS,895 VS, a45 vs br, 755 S, 720 s, 680 m cm-l; 'H NMR (C6D6, 200 MHz) 6 0.32 [s, Si(CHd31, 1.35 (m, CH~CHZO), 1.71 (m, CHd, 3.37 (m, CH2N), 3.71 (m, CH2CH20); l3C NMR (C6D6, 50.3 MHz) 6 0.3 [Si(CH&], 25.6 (CH2CH20), 37.8 (CH21, 51.3 (CHzN), 70.3 (CHzCH20); 29SiNMR (C&3,39.8 MHz) 6 0.7. Anal. Calcd for C1,&&lzN20&32Zr: C, 39.06; H, 7.71; N, 5.36. Found: C, 38.78; H, 7.81; N, 5.43. (4) Preparationof CHz(CHzNSiMes)&rClz(CsH6N)z(4). To a stirred suspension of 1.74 g (4.60 mmol) of CHz(CH2NSiMe3)zZrClz (2) in 20 mL of toluene was added 5 mL (4.90 g, 61.95 mmol) of pyridine. After the solution was stirred for 1 h, the solvent was evaporated in vacuo. The residue was washed twice with 10 mL of pentane and dried in vacuo: yield 1.65 g (67%); mp 113 "C dec; IR (KBr) 3060 m, 2950 vs, 2890 5, 2860 9, 1995 W, 1935 W, 1865 VW, 1638 W, 1602 VS, 1572 W, 1485 m, 1468 m, 1442 vs, 1408 w, 1348 w, 1325 vw,1305 VW, 1245 VS, 1220 8, 1152 W, 1068 9, io40 VS,io10 S, 938 VS, 865 VS, 835 vs br, 808 s, 755 s, 715 s, 702 s, 678 s cm-'; IH NMR (C&h3,200 MHz) 6 0.07 [s Si(CH&], 1.67 [quint, 3J(HH) = 5.8 Hz, CH21, 4.19 (t, CHzN), 6.51 (m, metu-H of NC5H5), 6.87 (m, para-H of NC5H5), 9.06 (m, ortho-H of NC5H5); 13C NMR (C6D6, 50.3 MHz) 6 0.9 [Si(CH&I, 29.7 (CHz), 45.3 (CH2N), 123.8 (neta-C of NCaH5), 138.5 @uru-C of NC5H51, 152.1 (ortho-C of NC5H5); 29SiNMR (C6D6, 39.8 MHz) 6 1.0. Anal. Calcd for C1gH34Cl~N4Si2Zr:C, 42.51; H, 6.38; N, 10.44. Found: C, 42.48; H, 6.31; N, 10.42. (5) Preparation of CHz(CHzNSiMes)2Zr(Cp)CI(5). To a stirred solution of 2.51 g (4.80 mmol) of CHz(CH2NSiMe3)2ZrC12(THF)2 (3)in 50 mL of toluene was slowly added a solution of 347 mg (4.82 mmol) of LiCp in 30 mL of THF. After the solution was stirred for 16 h, the solvent was evaporated in vacuo. The residue was extracted with 50 mL of pentane, the extract filtered, and the volume of the solution reduced t o ca. 5 mL. Storage at -78 "C yielded CHz(CHzNSiMe3)zZr(Cp)C1(5) as a colorless crystalline solid: yield 1.49 g (76%); NMR (C&, 200 MHz) 6 0.08 [s, si(cH&], 1.20-1.51 (m, Hdc' of CHz), 3.00 [ddd, 2J(HaHb)= 14.8 Hz, V(HaHdC')= 7.7 Hz, V(HaHdC')= 4.0 Hz, Ha of CHHNI, 3.48 [ddd, 3J(HbHdc')= 5.8 Hz, V(HbHdC')= 4.5 Hz, Hb of CHHN], 6.21 (s, C5H5); 13C NMR (&De, 50.3 MHz) 6 1.0 [Si(CH&], 33.6 (CHz), 46.8 NMR (C6D6,39.8 MHz) 6 1.5. Anal. (CH2N), 112.1 (C5H5); 29si Calcd for Cl4HzgClN2SizZr: C, 41.19; H, 7.16; N, 6.86. Found: C, 41.16; H, 7.23; N, 6.91. (6)Preparation of CHz(CHzNSiMes)z(Cp)Zr-Fe(CO)zCp (6). To a solid mixture of 197 mg (0.48 mmol) of CHz(CH2NSiMe&Zr(Cp)C1(5)and 130 mg (0.62 mmol) of K[CpFe(C0)21 was slowly added 15 mL of toluene and 2 mL of THF. After the mixture was stirred for 1h, ca. 50 mg of Na powder was added and the reaction mixture stirred €or another 2 h. After evaporation of the solvent in vacuo, the residue was extracted with 20 mL of pentane, the extract filtered, and the solvent removed in vacuo. The residue was dissolved in 1.5 mL of diethyl ether and the solution stored at -78 "C. Compound CHz(CH2NSiMe&(Cp)Zr-Fe(CO)zCp (6)precipitated as a yellow highly crystalline solid which was dried in vacuo: yield 108 mg (41%); IR (pentane) 2017 m, 1947 vs, 1895 vs cm-I; 'H NMR (C6D6, 200 MHz) 6 0.13 [s, Si(c&),], 1.31 (m, HCof CHH), 1.46 (m, H'' of C W , 3.14 [ddd, V(H"Hb) = 15.7 Hz, = 5.6 Hz, Ha of CHHN], 4.12 3J(HaHdc)= 5.7 Hz, 3J(HaHC'C') [s, (CJT5)Fe], 4.20 [ddd, V(HbHdc')= 6.2 Hz, 3J(HbHdc')= 4.9 Hz, Hb of CHHNI, 6.30 [s, (C5H5)Zrl;l3C NMR (C6D6, 50.3 MHz) 6 1.4 [Si(CH&], 30.6 (CHd,42.8 (CHZN),81.4 [(CsHdFeI, 110.9 [(C5Hb)Zr],218.6 (CO); 29SiNMR (C6D6, 39.8 MHz) 6 = 2.7. Anal. Calcd €or CzlHa4FeNzOzSizZr: C, 45.88; H, 6.23; N, 5.10. Found: C, 45.90; H, 6.25; N, 5.11. (7) Preparation of CHz(CHzNSiMes)2(Cp)Zr-Ru(CO)zCp (7). To a solid mixture of 423 mg (1.04 mmol) of CHz(CHz-

5346 Organometallics, Vol. 14,No.11, 1995

Friedrich et al.

NSiMe&ZdCp)Cl (5) and 290 mg (1.10 mmol) of K[CpRuX-ray Crystallographic Study of CH2(CH2NSiMe&(Cp)Zr-Fe(CO)&p (6). A yellow block-shaped crystals of 6 (CO)z],which was cooled to -25 "C, were slowly added 20 mL of cold toluene and 1 mL of THF. The reaction mixture was was mounted under argon in a Lindemann capillary. The warmed t o room temperature over a period of 16 h. After X-ray diffraction data were collected by using a Philips PW evaporation of the solvent in vacuo, the residue was extracted 1100 diffractometer with graphite-monochromated Mo Ka radiation. Un5t cell parameters were determined by a leastwith 20 mL of pentane, the extract filtered, and the solvent squares analysis of 25 automatically centered reflections in removed in vacuo. The residue was redissolved in 2 mL of the range of 10" < 0 < 15". Data were collected at 295 K in diethyl ether and the solution stored at -78 "C. Compound the range of 0 = 3-25" with a scan width of 0.80" by using a CHz(CHzNSiMe3)2(Cp)Zr-Ru(CO)&p (7) precipitated as a technique described previously.1° yellow highly crystalline solid which was dried in vacuo: yield Crystal data for 6: C21H3~N20&FeZr, monoclinic, space 445 mg (72%);IR (toluene) 2880 vs, 2850 vs, 2015 m, 1957 vs, group P21/c, M = 549.75, Z = 4, a = 10.446(3)A, b = 26.5041895 vs, 1362 w, 1288 m, 1248 s, 1190 m, 1170 m, 1066 vs, (5) A, c = 10.446(3)A, = 112.71(4)", V = 2574.39 A3, pcaic= 912 VS, 865 S, 840 S, 800 s cm-'; 'H NMR (C6D6,200 MHz) 6 0.13 [s, Si(CH&], 1.32 (m, Hc of CHH), 1.41 (m, H'' of CHH), 1.418 g cm-', F(OO0) = 1136, p(Mo Ka)= 10.2 cm-l. The structure solution and refinement were carried out with 3.11 [ddd, 2J(HaHb)= 15.7 Hz, 3J(HaHdC') = 6.3 Hz, 2J(HaHdC') the programs of the SHELX 76 software package. The = 4.9 Hz, Ha of CHHN], 4.18 [ddd, 3J(HbHdc')= 5.7 Hz, coordinates of the metal atoms were deduced from a Patterson 'J(HbHc"') = 5.7 Hz, Hb of CHHN], 4.64 [s,(Cas)Rul, 6.34 [s, synthesis. The remaining atoms were located from subsequent (Ca5)ZrI; I3C NMR (C6D6, 50.3 MHz) 6 1.5 [Si(CH&I, 30.8 difference Fourier syntheses and the hydrogen atoms were (CHz), 42.6 (CHzN), 84.7 [(C~H~)RU], 110.7 [(C5H5)Zrl,207.1 included in the structure factor calculations with thermal (Co); 29si NMR (C6D6, 39.8 MHz) 6 2.8. Anal. Calcd for factors of 0.08 k, but their parameters not refined. Empirical C~IH~~N~O~R C,U42.39; S ~ ~ H, Z ~5.76; : N, 4.71. Found: C, absorption corrections, using the program DIFAEW were 42.28; H, 5.65; N, 4.63. applied to all data, after initial refinement with isotropic ( 8 ) Preparation of CHz(CH2NSiMe&(Cp)Zr-Co(CO)sthermal parameters for all atoms. In the final cycles the full(PPh3) (8). To a solid mixture of 314 mg (0.77 mmol) of matrix least-squares refinement anisotropic thermal paramCHz(CHzNSiMe3)2Zr(Cp)C1(5) and 468 mg (0.82 mmol) of Naeters were assigned to all non-hydrogen atoms with weights [Co(C0)3(PPh3)](THF)2,which was cooled to -20 "C, was of l/u2(F)for individual reflections. Refinement converged at slowly added 20 mL of cold toluene. The reaction mixture was R = 0.046 and R, = 0.045 for 3253 data with ZIdZ) > 3 and warmed t o room temperature over a period of 2 h and stirred 265 parameters. for another 20 min. After removal of the solvent in vacuo, the residue was extracted with 30 mL of pentane, the extract filtered, and the volume of the solution reduced to ca. 5 mL. Results and Discussion Storage at -60 "C yielded CHz(CHzNSiMe3)2(Cp)Zr-Co(C0)3Synthesis of Chelate-(Diamido)dichlorozirco(PPh3) (8)as a yellow solid: yield 210 mg (35%);IR (toluene) nium Complexes and the Half-Sandwich Com1902 VS, 1887 vs cm-'; 'H NhfR (C6D6, 200 MHz) 6 0.19 [S, pound CHz(CH2NSiMe&Zr(Cp)C!l (5). The most Si(C&)31, 1.39 (m, Hcof CHH), 1.62 (m, H" of CHH), 3.37 [ddd, 2J(HaHb)= 16.1 Hz, V(HaHdC')= 5.7 Hz, 3J(HaHdc')= 5.5 Hz, versatile synthetic strategy for the synthesis of CpHa of CHHN], 4.33 [ddd, 3J(HbHdc')= 5.7 Hz, V(HbHdc')= 5.7 (RNNR)z-half-sandwichcomplexes is based upon an Hz, Hb of CHHN], 6.52 (s, C5H5), 6.93-7.04, 7.51-7.59 [m, initial introduction of the amido ligand at the metal P(c&5)31; l3cNMR (C6D6, 50.3 MHz) 6 1.3 [Si(CH&], 29.9 center and the subsequent substitution of a halide (CH2),43.2 (CH2N), 111.8 (C5H5), 128.6 [d, 3J(PC)= 10.3 Hz, ligand by LiCp. The "difunctional" (diamid0)dichlo= meta-C of C&], 129.9 (s, para-c of C6H5), 133.4 [d, 2J(Pc) rozirconium complex CHz(CHzNSiMe3)zZrClz(2), a key 11.9 Hz, ortho-C of C&], 136.6 [d, 'J(PC) = 39.9 Hz, ipso-C intermediate in the synthesis of the type of halfO f C&,], 207.2 [br, co, 2J(Pc) not resolved]; 29siNMR (C6D6, sandwich complex mentioned above, is most conve39.8 MHz) 6 3.7; 31PNMR (C6D6, 81.0 MHz) 6 62.0. Anal. niently prepared by a ligand redistribution upon reacCalcd for C35H44CoN203PSi2Zr: C, 54.03; H, 5.70; N, 3.60. tion of the symmetrical species [CHz(CHzNSiMe3)212Zr Found: C, 54.28; H, 5.58; N, 3.53. (9) Preparation of CH2(CHzNSiMes)dCp)Zr-Co(C0)3- (1)with ZrCk in toluene at 60 "C (Scheme 1). The route via the spirocyclic system 1 was chosen in view of the (PpTOl3) (9). To a solid mixture of 260 mg (0.64 mmol) of CHz(CHzNSiMe&Zr(Cp)C1(5) and 400 mg (0.65 mmol) of Nalow solubility of the probably oligomeric complex 2 in [Co(C0)3(PpTo13)](THF)z, which was cooled to -20 "C, was aromatic hydrocarbons which prohibited the separation slowly added 20 mL of cold toluene. The reaction mixture was of LiCl generated in the direct synthesis based upon a slowly warmed to room temperature and stirred for another 1:l stoichiometric reaction of the lithiated amine [CH220 min. After removal of the solvent in vacuo, the residue was {CHzN(Li)SiMe3}2],with ZrCl4. The method employing extracted with 30 mL of pentane, the extract filtered, and the the ligand redistribution was first reported by Burger volume of the solution reduced to ca. 5 mL. Storage at -60 "C yielded C H ~ ( C H ~ N S ~ M ~ ~ ) ~ ( C ~ ) Z ~ - C(9) O (asCaO ) ~ (and P ~ Tco-workers ~ ~ ~ ) in their synthesis of several chelating amido-zirconium halides.12 In the presence of the yellow solid: yield 168 mg (32%);IR (toluene) 1900 vs, 1885 donor solvents THF and pyridine, 2 is converted to the VS cm-'; 'H NMR (C&, 200 MHZ) 6 0.22 [S, Si(cH&], 1.37 hexacoordinate solvent adducts CH2(CH2NSiMe3)2(m, H'Of cm),1.58 (m, H" O f C m ) , 1.94 (S, CH&&), 3.41 [ddd, 2J(HaHb)= 15.7 Hz, 3J(HaHdC')= 6.1 Hz, V(HaHdc')= ZrClz(THF12 (3)and CHZ(CH~NS~M~~)ZZ~C~~(NC~H 5.0 Hz, Ha of CHHN], 4.38 [ddd, 3J(HbHdc') = 5.7 Hz, 3J(HbHdc') (4), respectively, which are soluble in benzene or toluene = 5.7 Hz, Hb of CHHN], 6.57 (s,C5H5), 6.92 [dd, 3J(H0rthoHmeta) and may therefore be conveniently employed in further = 7.9 Hz, 4J(HP) = 1.8 Hz, meta-H of C&14CH3], 7.66 [dd, transformations. The THF-adduct 3,in particular, was 3J(HP)= 10.7 Hz, ortho-H O f C6H4CH31; 13C NMR (C6D6, 50.3 found to be a useful reagent since it spontaneously loses MHz) 6 1.4 [Si(CH3)31,21.1 (m3C6H4), 29.9 ( C H 2 ) , 43.2 (CHzN), 111.7 (C5H51, 129.4 [d, 3J(PC)= 9.9 Hz, metu-C of C6H4CH31, (10)Cooper, M. K.;Guerney, P. J.; McPartlin, M. J . Chem. SOC., 133.5 [d, 2J(PC) = 11.9 Hz, ortho-C of CsH4CH31, 136.8 [d, Dalton Trans. 1982,757. 'J(PC) = 42.0 Hz, ipso-c of C&CH3], 139.8 [s,para-c of C a 4 (11)Walker, N.;Stuart, D. Acta Crystallogr., Sect. A 1983,39,158. Beiersdorf, D. Z . Allg. Anorg. Chem. 1979,459, (12)(a)Burger, H.; CH31,207.7 [br, CO, 2J(PC)not resolved]; '%i NMR ( c a s , 39.8 111. (b)Wiegel, K.;Burger, H. Ibid. 1976,426,301.( c ) Brauer, D.J.; MHz) 6 3.6; 31PNMR (C6D6, 81.0 MHz) 6 59.2. Anal. Calcd Burger, H.; Essig, E.; Gschwandtner, W. J. Organomet. Chem. 1980, for C ~ ~ H ~ O C O N ~ O JC,? S55.65; ~ ~ Z H, ~ : 6.15; N, 3.42. Found: Gschwandtner, W.; Liewald, G. R. Ibid. 1983, 190,343.(d) Burger, H.; C, 55.28; H, 6.28; N, 3.53. 259,145. ~~~

Zr- M Hetero bimetal1 ics

Organometallics, Vol. 14,No. 11, 1995 5347

Scheme 1. Synthesis of CH2(CH2NSiMe3)2ZrC12(L)2 (L= THF' (3),Pyridine 4)) ,Si Me5

Me3Si

\

NH

1 ) 2 eq nBuLi

NH

2) 0.5 eq ZrC14

\SiMe3

)C(51

1

MesSi

b,N>,zr Me3&

'CI

.

I n 2

1

THF

Yb)

C E I

.-t

k"Pizr+ ' THI F Me3 Si 3

Scheme 2. Synthesis of the Zr-M Heterodinuclear Complexes 6-9

Figure 2. Molecular structure of 6 in the crystal: (a)View perpendicular to the Fe-Zr axis; (b) view along the Zr-Fe axis showing the gauche conformation of the Cp rings in the two molecular halves.

1 6

7

L = PPhS

8

PToIs

9

its solvent ligands upon substitution of the halide by a bulkier anionic ligand. Reaction of 3 with 1molar equiv of LiCp smoothly yielded the half-sandwich complex CH2(CH2NSiMe&Zr(Cp)Cl(5) in 76%yield (eq 1). TUF

3

5

Synthesis of the Zr-M Heterobimetallic Complexes (M = Fe, Ru, Co). Reaction of 5 with the metal carbonylates K[Cp(C0)2Fe],K[CpCO)2Ru],Na[Co(CO)s(PPh3)], and Na[Co(CO)3(PTo13)1yielded the corresponding heterobimetallic complexes 6-9 (Scheme 2). Due some degree of single electron transfer from the carbonylate to the Zr complex as a reaction competing with the metathetical condensation in the formation of the

Zr-Co complexes, these species were only obtained in a yield of 35% ( 8 ) and 32% (9). The effective C, symmetry of 6 and 7 reflected in the lH-, 13C-, and 29Si-NMRspectra indicates either free rotation around the metal-metal bond or a libration around this bond generating the apparent C,symmetry. This rotation (or libration) could not be frozen out at 180 K although exchange broadening is observed below 210 K. The shift of the v(C0) bands to higher wavenumbers relative to those of the alkali metal salts of the anions is a n indirect indication of the formation metal-metal bonds. Electron density is thus transferred to the Lewis acidic early transition metal center. The shift of the asymmetric l2C-0 stretching frequency, in particular, may be viewed as a measure of the acceptor strength of the Lewis acidic metal fragment relative to the base [Cp(CO)2M]-. l3 It is particularly interesting to compare the position of the v(C0) bands in the complexes of type A (Casey), type B (tripodamido-zirconium) and, as first described here, type C (Cp/diamido-Zr) (Table 1). As is readily apparent, less electron density is withdrawn from the carbonyl metal fragment by the 16-electron fragment [Cp2ZrX]+ than by the 14-electron fragment [Cp(13) See for example: Fischer, R. A.; Priermeier, T. Organometallics 1994, 13, 4306 and references cited therein.

Friedrich et al.

5348 Organometallics, Vol. 14, No. 11, 1995 Table 1. Carbonyl Infrared Bands in Complexes of Types A-C compd type M ~ S ~ ~ S ~ M ~ Z N ( ~ - C H ~ C ~ H ~ ) } ~ Z ~ - M ( CBO ) ~ C ~ CHz(CHzNSiMe3)2(Cp)Zr-M(CO)zCp C Cpz(Cl)Zr-M(CO)zCp A Cpz(Me)Zr-M(CO)zCp A Cpz(tBuO)Zr-M(CO)zCp A a

G O ) (%In, Zr-Fe (cm-l) 1961,1910 1947.1895 1937,1872 1939,1874

h8)

Zr-Ru (cm-') 1986,1932 1957.1895 1953,1886 1950,1880 1958,1884

ref 6 a la la la

This work (recorded in toluene).

Table 2. Selected Bond Lengths (A) and Bond Angles (deg) for 6 Zr-Fe Zr-C(9) Zr-C(l7) Zr-C(19) Zr -C(21) Fe-C(11) Fe-C(l3) Fe-C(15) Si(l)-C(l) Si(l)-C(3) Si(2)-C(4) Si(2)-C(6) C(10)-0(10) N(1)-Zr-Fe C(S)-Zr-N(l) N(2)-Zr-N(1) C(171-Zr-Fe C(17)-Zr-C(9) C(181-Zr-Fe C(18)-Zr-C(9) C(18)-Zr-C(17) C(19)-Zr-N(1) C(19)-Zr-N(2) C(19)-Zr-C(18) C(20)-Zr-N(1) C(20)-Zr-N(2) C(20)-Zr-C(18) C(21)-Zr-Fe C(21)-Zr-C(9) C(21)-Zr-C(17) C(21)-Zr-C(19) C(lO)-Fe-Zr C(ll)-Fe-C(lO) C(12)-Fe-C(10) C(131-Fe-Zr C(13)-Fe-C(11) C(141-Fe-Zr C(14)-Fe-C(11) C(14)-Fe-C(13) C(15)-Fe-C(10) C(15)-Fe-C(12) C(15)-Fe-C(14) C(lG)-Fe-C(lO) C(16)-Fe-C(12) C(16)-Fe-C(14)

2.745(1) 2.632(5) 2.529(5) 2.579(5) 2.523(5) 1.689(6) 2.108(6) 2.116(6) 1.848(7) 1.865(6) 1.867(8) 1.858(7) 1.163(7) 108.1(1) 34.0(2) 94.6(2) 133.3(1) 134.9(2) 101.3(1) 166.8(2) 32.0(2) 121.3(2) 132.1(2) 31.6(2) 91.0(2) 137.7(2) 52.8(2) 137.3(1) 116.8(2) 32.1(2) 52.4(2) 87.7(2) 94.6(3) 96.8(3) 82.0(2) 135.1(3) 99.0(2) 102.4(3) 39.1(2) 133.1(3) 65.0(3) 39.1(3) 100.3(3) 38.8(2) 65.0(3)

Zr-N(1) Zr-N(2) Zr-C(18) Zr-C(2O) Fe-C(10) Fe-C(l2) Fe-C(14) Fe-C(16) Si(l)-C(2) Si(1)-N( 1) Si(2)-C(5) Si(2)-N(2) C(ll)-O(ll) C(S)-Zr-Fe N(2)-Zr-Fe N(2)-Zr-C(9) C(17)-Zr-N(1) C(17)-Zr-N(2) C(18)-Zr-N(1) C(18)-Zr-N(2) C(lS)-Zr-Fe C(19)-Zr-C(9) C(19)-Zr-C(17) C(201-Zr-Fe C(20)-Zr-C(9) C(20)-Zr-C(17) C(20)-Zr-C(19) C(21)-Zr-N(1) C(21)-Zr-N(2) C(21)-Zr-C(18) C(21)-Zr-C(20) C(ll)-Fe-Zr C(12)-Fe-Zr C(12)-Fe-C(11) C(13)-Fe-C(10) C(13)-Fe-C(12) C(14)-Fe-C(10) C(14)-Fe-C(12) C(151-Fe-Zr C(15)-Fe-C(11) C(15)-Fe-C(13) C(lG)-Fe-Zr C(lG)-Fe-C(ll) C(16)-Fe-C(13) C(16)-Fe-C(15)

2.039(4) 2.047(5) 2.541(5) 2.572(5) 1.733(7) 2.077(7) 2.101(6) 2.104(6) 1.866(6) 1.748(4) 1.849(8) 1.741(5) 1.198(6) 91.8(1) 111.9(1) 73.1(2) 112.6(2) 86.8(2) 138.8(2) 100.5(2) 87.4(1) 152.6(2) 52.2(2) 105.9(1) 124.6(2) 52.7(2) 31.5(2) 85.8(2) 106.7(2) 53.2(2) 32.0(2) 84.5(2) 106.7(2) 164.2(3) 127.1(3) 39.8(2) 162.2(3) 65.5(3) 137.9(2) 99.3(3) 65242) 145.0(2) 128.0(3) 65.9(2) 38.3(3)

(amide)zZrl+. The Lewis acidity at the Zr is in turn markedly further increased on going t o the 12-electron fragment [(tripodtriamide)Zr]+. Infrared absorptions attributable to bridging carbonyl or isocarbonyl ligands were not observed in the spectra recorded for 6-9 which supports the structural arrangements depicted in Scheme 2. Crystal Structure of CHz(CHzNSiMe&(Cp)ZrFe(C0)zCp (6). We have recently carried out the first structural characterization of a compound with an unsupported Zr-Fe bond, MeSi{SiMezN(4-CH3CsH4)}3Zr-Fe(CO)zCp which was found to have a Zr-Fe bond length of 2.605(2) A. In view of this result, the effect that the ligand shell a t the early transition metal has upon the metal-metal bond was of particular

Table 3. Fractional Atomic Coordinates for 6 atom

X

0.34383(5) 0.37448(8) 0.0836(2) -0.0712(7) 0.1195(7) 0.0400(7) 0.6901(2) 0.8141(7) 0.7319(9) 0.7203(7) 0.2278(4) 0.3304(6) 0.4379(7) 0.4927(6) 0.5192(4) 0.4453(7) 0.4928(6) 0.5251(6) 0.6323(4) 0.1851(7) 0.1626(6) 0.2398(7) 0.3055(7) 0.2708(7) 0.3338(6) 0.3552(6) 0.2338(7) 0.1391(6) 0.2025(6)

Y

z

0.13727(2) 0.06510(3) 0.1135(1) 0.1342(3) 0.1589(3) 0.0512(2) 0.1626(1) 0.1151(3) 0.2243(3) 0.1667(3) 0.1072(2) 0.0684(2) 0.0866(3) 0.1385(3) 0.1448(2) 0.1116(3) 0.1408(2) 0.0520(2) 0.0388(1) 0.0598(3) 0.0531(2) 0.0101(3) -0.0094(2) 0.0214(3) 0.2326(2) 0.2178(2) 0.1941(2) 0.1927(2) 0.2163(2)

0.08922(5) 0.29456(8) -0.2682(2) -0.2367(7) -0.3912(6) -0.3608(7) 0.1461(2) 0.1272(8) 0.0873(10) 0.3399(7) -0.1066(4) -0.1038(6) -0.1652(7) -0.1106(6) 0.0466(4) 0.4231(6) 0.5152(5) 0.2764(6) 0.2700(5) 0.3162(8) 0.1685(7) 0.1637(8) 0.3043(8) 0.3964(7) 0.0902(7) 0.2303(6) 0.2243(6) 0.0816(6) -0.0019(6)

interest. Single crystals of 6 could be readily obtained from diethyl ether and were used to carry out a singlecrystal X-ray structure analysis of the compound. The molecular structure of 6 is depicted in Figure 2, the principal bond lengths and interbond angles are given in Table 2, and the positional parameters are listed in Table 3. The crystal structure analysis unambiguously establishes the presence of an unsupported metal-metal bond linking the two complex fragments. Although the two carbonyl ligands are slightly tilted toward the Zr center [