Organometallics 1995, 14, 2725-2732
2725
Ligand-Induced C,C Coupling and C,C Bond Breaking in Diarylfulvene Complexes of Cobalt(0) Hans-Friedrich Klein,"!? Emmanuel Auer,? Thomas Jung,' and Caroline Rohr$ Institut fur Anorganische Chemie der Technischen Hochschule Darmstadt, Petersenstrasse 18, 64287 Darmstadt, FRG, and Hochschulstrasse 10, 64289 Darmstadt, FRG Received August 25, 1994@
6,6-Diarylpentafulvenes upon coordination by odd-electron (trimethylphosphine)cobalt(O) moieties undergo a reductive C,C coupling reaction in the 1-position of the Cg ring, forming dinuclear (y3-allyl)cobalt(I) compounds. The C,C coupling is reversed under ambient conditions by reaction of the metal with carbon monoxide. Even-electron methyl- or phenyl(trimethylphosphine)cobalt(I) moieties accommodate 6,6-diarylfulvenes a s v4-diene ligands in mononuclear complexes.
Introduction Coordination of olefins by zerovalent cobalt (d9)supported by three trimethylphosphine ligands is observed in molecular complexes that attain 17 metal valence electrons and can be regarded as stable radicals1 under ambient conditions. Formally replacing the olefin and one of the phosphines, nonconjugated diolefins may be introduced as chelating ligands without altering the paramagnetic valence state,2while azulene upon coordination is reduced by two (trimethy1phosphine)cobalt units t o form a dinuclear cobalt(1) complex containing the v5:v3-azulene d i a n i ~ n . ~ We have been investigating substitution reactions of mononuclear cobalt(0) complexes using pentafulvenes as electron-accepting JCligands. These gave unexpected products containing transformed hydrocarbon ligands. We report here on a new C,C-couplingmode via radical reactions in the ligand periphery that is initiated by the odd-electron metal center and can be reversed by admitting carbon monoxide. When coordinated to a single transition metal, penv5tafulvenes may act as v2-olefin,4~ 7 ~ - a l l ydiene,^ l,~ ~yclopentadienyl,~ or @triene8 ligands (Chart 11,while in dinuclear complexes a still greater variety of coordination modes has been o b s e r ~ e d .Radical ~ anion intermediates have been suggestedlO for some of these pentafulvene transformations. TH Darmstadt, Petersenstrasse 18, 64287 Darmstadt, FRG. : TH Darmstadt, Hochschulstrasse 10, 64289 Darmstadt, FRG. Abstract published in Adcance ACS Abstracts, May 1, 1995. 11, Klein, H.-F.; Lull, G.; Rodenhauser, B.; Cordier, G.; Paulus, H. ~
Z . Naturforsch. 1988, B43, 1256. 121\a) Klein, H.-F.; Gross, J.; Witty, H.; Neugebauer, D. 2.Naturforsch. 1984,B39,643. .b, Klein, H.-F.; Fabry, L.; Witty, H.; Schubert, U.; Lueken, H.; Stamm, U.Inorg. Chem. 1985,24, 683. 13, Klein, H.-F.; Hammerschmitt, B.; Lull, G.; Florke, U.; Haupt, H.-J. Inorg. Chim. Acta 1994,218, 143. 4) Edelmann, F.; Jens, K. J.; Behrens, U.Chem. Ber. 1984, 117, 344. ( 5 ) Edelmann, F.; Wormsbacher, B.; Behrens, U.Chem. Ber. 1978, 111, 817.
161Rau, D.; Behrens, U.J. Organomet. Chem. 1990,397, 219. 17) Jeffery, J.; Probitts, E. J.; Mawby, R. J . J. Chem. Soc., Dalton Trans. 1984, 2423. 18) (a, Fischer, E. 0.; Semmlinger, W. Naturwzssenschaften 1961, 48,535. (biCooper, R. L.; Fischer, E. 0.; Semmlinger,W. J. Organomet. Chem. 1967,9, 333. (9, la, Toefke, S.; Haupt, E. T. K.; Behrens, U. Chem. Ber. 1986, 119,96.tbJ Behrens, E.; Weiss, E . J . Organomet. Chem. 1975,96,399.
0276-733319512314-2725$Q9.QQlQ
Chart 1
R = Aryl L = Cyclooctadlene
Phi(
Ph
9 co
Cc
R = CH, Ph
co R = Phenyl
Experimental Section General Procedures and Materials. Standard vacuum techniques were used in manipulations of volatile and airsensitive materials.'l Literature procedures were followed in the syntheses of Co(~lefin)(PMe&,,~~ CoCH3(PMe3)4,13 6-(4methylphenyl)-6-phenylfulvene,146,6-dipheny1fulvene,l5 6,6bis(4-methylphenyl)fuul~ene,~~ 6,6-bis(4-~hlorophenyl)fulvene,~~ 6,6-bis(4-methoxypheny1)fulvene,l8 6,6-bis(4-(dimethylamino)(10) Rinehart, K. L.; Frerichs, A. K.; Kittle, P. A,; Westman, L. F.; Gustavson, D. H.; Pruelt, R. L.; McMahon, J. E. J . Am. Chem. SOC. 1960, 82, 4111. (11)Klein, H.-F.; Mager, M.; Florke, U.; Haupt, H.-J.; Breza, M.; Boca, R. Organometallics 1992, 11, 2912. (12) Klein, H.-F.; Lull, G.;Rodenhauser, B.; Cordier, G.;Paulus, H. 2.Nuturforsch. 1988,43B, 1256. (13)Klein, H.-F.; Karsch, H. H. Chem. Ber. 1983, 108, 944. (14) Konovalow, A. I.; Yarkowa, E. G.; Salikhov, I. S.; Izmailowa, R. G. Zh. Org. Chem. 1967,3, 1319. (15)(a)Jeffery, J.; Probitts, E. J.; Mawby, R. J. J.Chem. Soc., Dalton Trans. 1984,2423. (b)Day, J. H. Chem. Reu. 1953,53, 167. (c) Probitts, E. J.; Mawby, R. J. J. Orgunomet. Chem. 1986,310,121.
0 1995 American Chemical Society
2726 Organometallics, Vol. 14, No. 6, 1995
Klein et al.
rimethylphosphine)dicobalt(I)(4). Co(C2H4)(PMe3)3(830 phenyl)fulvene,la 6-(dimethylamino)f~lvene,'~ and triphemg, 2.63 mmol) in 40 mL of pentane and 6,6-bis(4-chlorophenylphosphonium cyclopentadienide.20 Methods of characterny1)fulvene (590 mg, 1.97 mmol) in 80 mL of pentane were ization have been described elsewhere.21 For air-sensitive combined at -70 "C. Within 5 min the mixture turned red. compounds elemental analyses correct within 1%were reAfter this mixture was warmed to 20 "C and filtered, the garded t o be tolerable. volume was reduced to 60 mL in vacuo, affording 1200 mg of Preparations. Synthesis of [(1-3-q):(1-3-q)-4,4'-Bisa dark red solid (85%);dec pt > 120 "C. Anal. Calcd for C54H78(diphenylmethylidene)-5,5'-dihydrofulvalenelhexakis(tc14co2P6 (1172.1): C, 55.90; H, 7.15; P, 15.49. Found: C, rimethylphosphine)dicobalt(I) (I). To a solution of Co(c55.33; H, 6.70; P, 15.86. 'H NMR (300 MHz, THF-de, 297 K): C5H8)(PMe3)3 (640 mg, 1.80 mmol) in 70 mL of pentane at 0 G(PCH3) 0.85 (dbroad)),54 H), G(H-5,H-5') 2.26 (s, 2 H), G(H"C was added dropwise 6,6-diphenylfulvene (410 mg, 1.78 l,H-l',H-3,H-3') 3.18 (s, 2 H) and 3.21 (s, 2 H), G(H-2J3-2') 4.45 mmol) in 70 mL of pentane. After 2 h at 20 "C the red solution (a 2 H), G(Ca4) 6.90-7.55 (m, 16 HI. was filtered and the volume reduced to 40 mL. At -20 "C Preparation of [(1-3-q):(1'-3'-q)-4,4'-Bis[bis(4-meth780 mg of dark red shining crystals was isolated (75%);dec pt oxyphenyl)methylidene]-5,5'-dihydrofulvalenelhexakis2140 "C. Anal. Calcd for C54H&O& (1035.0): c, 62.72; H, (trimethylphosphine)dicobalt(I)(5). Co(C2Hd)(PMe&(750 8.00. Found: C, 63.34; H, 8.40. lH NMR (300 MHz, THFmg, 2.38 mmol) in 150 mL of ether at -70 "C was combined ds): 305 K, G(PCH3) 0.95 (s, 54 H), 6(H-5,H-5') 2.30 (s, 2 H), with 6,6-bis(4-methoxyphenyl)fulvene(670 mg, 2.31 mmol). G(H-l,H-l',H-3,H-3') 3.13 (5, 4 H), 6(H-2,H-2') 4.35 (s, 2 H), The mixture was warmed to form a red-brown solution. After G(Ca.5) 6.75-7.30 (m, 20 H); 193 K, G(PCH3) 0.95 (s, 54 H), 3 h at 20 "C a slight turbidity was removed by filtration, and G(H-5,H-5'), 2.30 (s, 2 H), S(H-l,H-l',H-3,H-3'), 2.99 (8, 2 H) the volume of the solution was reduced to 40 mL. At -20 "C and 3.13 (s, 2 H); G(H-2,H-2') 4.35 (s, 2 H), G(CdZ5) 6.75-7.30 dark red rods were obtained that after drying in vacuo gave (m, 20 H). I3C NMR (75 MHz, THF-da, 297 K): G(C-5,C-5') 780 mg of a red powder (75%);dec pt > 140 "C. Anal. Calcd 15.7, G(PCH3) 22.7, G(C-l,C-l',C-2,C-2',C-3,C-3') 48.3, 52.0, for C56HgoC0204P6 (1155.0): c, 60.30; H, 7.85; P, 16.08. 55.6, and 66.2, 6(CarOmat) 116.5, 123.2, 125.3, 126.3, 128.4, Found: C, 60.11; H, 8.10; P, 15.19. 'H NMR (300 MHz, THF128.5,129.5,130.2, and 132.2, G(C,,,d 146.8, 149.6, and 155.8. de, 297 K): G(PCH3) 0.90 (s, 54 H), G(H-5,H-5') 2.25 (s, 2 H), Synthesis of [(1-3-q):( 1'-3'-~)-4,4'-Bis[ (4-methylpheG(NCH3) 2.71 (s, 12 H) and 2.79 (s, 12 H), 6(H-1,HH-1',H-3,Hnyl)phenylmethylidene]-5,5'-dihydrofulvalenelhexakis3') 3.05 (s, 2 H) and 3.25 (s, 2 H), 6(H-2,H-2') 4.10 (s, 2 HI, (trimethylphosphine)dicobalt(I) (2). Solutions of CO(CG(Ca4) 6.55-7.03 (m, 16 H). C5Ha)(PMe3)3(680 mg, 1.91 mmol) in 60 mL of pentane and of Preparation of [(1-3-q):( 1'-3'-q)-4,4'-Bis[bis(4-(dim6-(4-methylphenyl)-6-phenylfulvene (460 mg, 1.89 mmol) in 80 ethylamino)phenyl)methylidenel-S,5'-dihydrofulvalenelmL of pentane were combined dropwise at 20 "C to give a dark hexakis(trimethylphosphine)dicobalt(I)(6).To a solution red solution. After 4 h this was filtered and the volume was of Co(C2H4)(PMe3)3(520 mg, 1.65 mmol) in 40 mL of ether was reduced t o 50 mL in vacuo. At -20 "C 800 mg of small dark added at 20 "C 6,6-bis(4-(dimethylamino)phenyl)hlvene(500 red sticks with shiny surfaces were obtained (70%);mp 122mg, 1.58 mmol) in 100 mL of ether. Within 30 min the mixture 124 " c dec. Anal. Calcd for C ~ ~ H ~ ~ (1062.3): C O Z P ~c, 63.31; formed a dark red solution. After 6 h this was filtered and H, 8.16; P, 17.49. Found: C, 63.78; H, 8.36; P, 17.88. 'H NMR the volume reduced to 80 mL. At 20 "C 760 mg of dark red (300 MHz, THF-de, 297 K): G(PCH3) 0.85 (5, 54 H), G(H-5,Hcubic rods with shiny surfaces was formed (80%);dec pt > 185 5') and 1.35 (s, 2 H), G(CH3) 2.24 (s, 6 HI, d(H-l,H-l',H-3,H-3') (1207.6): c, 61.68; H, "c. Anal. Calcd for C62H1&0&P6 3.00 (m, 4 H) B(H-2,H-2') 4.21 (s, 2 H), d(Ca5,C&4) 6.758.45; P, 15.39. Found: C, 61.77; H, 8.61; P, 14.92. 'H NMR 7.22 (m, 18 H). I3C NMR (75 MHz, THF-ds, 297 K): G(CCH3) (300 MHz, THF-de, 297 K): G(PCH3) 0.90 (s, 54 H), G(H-5,H14.4, d(C-5,C-5')21.3, G(PCH3)22.6,6(C-l,C-l',C-2,C-2',C-3,C5') 2.25 (s(broad), 2 H), G(NCH3) 2.71 (5, 6 H) and 2.79 (s, 6 3') 48.5,51.8,58.2,66.1, and 66.8, G(C,,,t) 123.0, 125.1, 128.4, H), G(H-lJi-l',H-3,H-3') 3.05 (s, 2 H) and 3.25 (s, 2 H), 6(H128.9, 129.1, 129.4, 129.9, and 132.1, d(CqUafi)143.2, 144.0, 2,H-2') 4.10 (s, 2 H), & C a d ) 6.79 (m, 16 H). 146.5, 149.5, and 155.5. Attempted Reactions with 6-(Dimethylamino)fulvene A sample recrystallized from ether was used for X-ray and Triphenylphosphonium Cyclopentadienide. (a)Sodiffraction. Preparation of [( 1-3-q):( 1'-3'-q)-4,4-Bis[bis(4-meth- lutions of Co(CzH4)(PMe3)3(950 mg, 3.01 mmol) in 80 mL of toluene were combined with mole equivalent amounts of the ylphenyl)methylidene]-5,5'-dihydrofulvalene] hexakis(tfulvenes at 20 "C, respectively. Heating the mixture to reflux rimethylphosphine)dicobalt(I) (3). Co(cGHe)(PMe3)3(710 for 3 h had no effect. Both fulvenes were recovered by mg, 2.00 mmol) in 60 mL of ether at 20 "C was combined with crystallization in 81% and 92% yields, respectively. 6,6'-bis(4-methylphenyl)fulvene(570 mg, 1.98 mmol) in 100 (b) Solutions of CoCH3(PMe& (500 mg, 1.32 mmol) in 50 mL of ether. The solution turned dark red, and 30 min later mL of toluene were treated likewise, giving 86% and 95% of after filtering, the volume was reduced t o 30 mL. At -20 "C unchanged fulvene, respectively. a dark red solid was precipitated (which was also obtained from pentane or toluene solutions): yield 740 mg (68%);dec Preparation of [(1-4-q)-6,6-Diphenylfulvenelmethylpt 2150 " c . Anal. Calcd for C58Hg&02P6 (1091.0): c, 63.79; bis(trimethylphosphine)cobalt(I) (7). CoMe(PMe3)d (340 mg, 0.90 mmol) in 100 mL of pentane at -70 "C was combined H, 8.31; P, 17.03. Found: C, 62.85; 8.79; P, 17.30. 'H NMR with 6,6-diphenylfulvene (200 mg, 0.87 mmol). The mixture (300 MHz, THF-ds, 297 K): G(PCH3) 0.85 (s, 54 HI, G(H-5,Hwas warmed t o become a red solution. After 6 h at 20 "C 5') 2.08 (s, 2 H), G(CCH3)2.30 (5, 12 HI, G(H-l,H-l',H-3,H-3') filtration and crystallization from a volume of 40 mL at 0 "C 3.22 (s, 4 H), 6(H-23-27 4.30 (s, 2 H), G ( C a 4 ) 6.94-7.28 (m, 16 H). afforded 390 mg of dark red-black shining crystals (98%);mp 105-106 "C. Anal. Calcd for C25H35CoP2 (456.4): C, 65.79; Preparation of [(1-3-q):(1'-3'-q)-4,4'-Bis[bis(4-~hloH, 7.72; Co, 12.91. Found: C, 64.91; H, 7.79; Co, 13.21. 'H rophenyl)methylidene]-S,5'-dihydrofulvalenelhexakis(tNMR (300 MHz, THF-de, 297 K): d(COcH3) -0.40 (s, 3 HI, G(PCH3) 1.14 (s, 18 H), G(H-2/3)4.15 ( ~ , H), 2 G(H-1/4) 5.05 (s, (16) (a) Alper, H.; Laycock, D. E. Synthesis 1980,799. (b) Fuson, R. C.; Bakker, G. R.; Vittimberga, B. J. Am. Chem. SOC.1959, 81, 264. 2 H), G(Ca5) 7.05-7.43 (m, 10 H). I3C NMR (75 MHz, THF(17) (a) Kresze, G.; Rau, S.; Sabelus, G.; Goetz, H. Justus Liebigs de, 297 K): b(CoCH3) -20.9, G(PCH3) 18.1,6(C-1/4,C-2/3)66.1 Ann. Chem. 1961,648,51,57.(b) Friedrichsen, W.; Oeser, H. G. Justus and 84.3, G(C-5)96.8, d(C6H5) 122.0,128.2, and 130.0,6(C,,,d Liebigs Ann. Chem. 1978, 1139. 142.5 and 146.6. (18) Rau, D.; Behrens, U.J . Organomet. Chem. 1990, 397, 219. (19) Hafner, K.; Vopel, K. H.; Ploss, G.; Konig, C. Justus Liebigs Preparation of [(1-4-q)-6,6-Bis(4-methylphenyl)fulAnn. Chem. 1963,661, 52. venelmethylbis(trimethylphosphine)cobalt(I) (8). CoMe(BOIRamirez, F.; Levy, S. J . Am. Chem. SOC.1957, 79, 67. (PMe3)4 (650 mg, 1.72 mmol) in 40 mL of pentane and 6,6(21) Klein, H.-F.;Bickelhaupt, A,; Hammerschmitt, B.; Florke, U.; bis(4-methylpheny1)fulvene (420 mg, 1.63 mmol) in 100 mL Haupt, H.-J. Organometallics 1994, 13, 2944.
Diarylfulvene Complexes of Cobalt(0)
Organometallics, Vol. 14, No. 6, 1995 2727
of pentane were combined at 0 "C to give a dark red solution (9, 2 H), 6 ( C a 4 )6.80 (m, 8 HI. NMR (75 MHz, THF-d8, which after 1 h a t 20 "C was filtered and reduced to 60 mL in 297 K): G(CoCH3) -23.2, G(PCH3) 16.4, G(NCH3) 39.2, 6(C-1/ vacuo. Crystallization at 6 "C gave 550 mg of deep red cubic 2/3/41 59.4 and 82.6, d(CsH4) 111.4 and 128.8, 6(CquaJ 138.8, rods with shiny surfaces (68%, not optimized); mp 139-139.5 140.0. and 146.0. "C. Anal. Calcd for C27H39CoP2 (484.5): C, 66.94; H, 8.11; Preparation of [(1-4-q)-6,6-DiphenylfulvenelphenylCo, 12.16. Found: C, 66.97; H, 8.25; Co, 12.18. IH NMR (300 bis(trimethylphosphine)cobalt(I) (13). c o P h ( P M e ~(910 )~ MHz, THF-de, 297 K): G(CoCH3) -0.65 (t, 3 H, 3J(PH) = 9.4 mg, 2.07 mmol) in 40 mL of pentane and diphenylfulvene (450 Hz), G(PCH3) 1.22 (d, 18 H, 'J(PH) = 7.2 Hz), G(CCH3) 2.39 (S mg, 1.95 mmol) in 60 mL of pentane were combined at -70 6 H), 6(H-2,H-3)4.15 (S 2 H), 6(H-l,H-4) 5.01 ( ~ , H), 2 6(C&4) "C. The mixture was warmed up t o -30 "C and within 2 h 6.95 (m, 8 H). I3C NMR (75 MHz, THF-de, 297 K): 6(COm3) formed a deep red solution. Filtering and concentrating to a -22.5, G(PCH3) 18.2, G(CCH3) 21.2, 6(C-1/4,C-2/3)61.7, 84.4, volume of 40 mL followed by cooling to -40 "C afforded 550 G(CsH4) 129.0 and 130.0, 6(CqUad) 132.1, 142.6, 143.8. mg of dark red shining crystals (53%, not optimized); dec pt Preparation of [( 1-4-q)-6-(4-Methylphenyl)-6-phenyl>95 "C. Anal. Calcd for C ~ D H ~ ~(518.5): C O P ~C, 69.40; H, 7.19; fulvenelmethylbis(trimethylphosphine)cobalt(I) (9). Co, 11.36. Found: C, 69.90; H, 7.75; Co, 11.48. IH NMR (60 CoMe(PMe& (550 mg, 1.45 mmol) in 50 mL of pentane and MHz. THF-de, 297 K): G(PCH3) 0.9 (s, 18 H), 6(H-2/3) 3.8 (s, 6-(4-methylphenyl)-6-phenylfulvene (340 mg, 1.40 mmol) in 70 2 HI, 6(H-1/4) 4.8 (s, 2 H), G(CoCa5) 6.3-6.5 (m, 5 HI, mL of pentane were combined a t 20 "C to give a deep red d(CCa5) 7.2-6.7 (m, 10 H). solution. After 3 h filtration and crystallization from a volume Preparation of [ (1-4-q)-6-(4-Methylphenyl)-6-phenylof 40 mL at -20 "C afforded 480 mg of dark red plates (72%); fulvenelphenylbis(trimethylphosphine)cobalt(I) (14). mp 112-113 "C. Anal. Calcd for C2&7CoP2 (470.5): C, 66.38; CoPh(PMe& (590 mg, 1.34 mmol) in 30 mL of pentane and H, 7.92; Co, 12.52. Found: C, 66.25; H, 8.15; Co, 11.85. IH 6-(4-methylphenyl)-6-phenylfulvene (3220 mg, 1.30 mmol) in NMR (300 MHz, THF-ds, 297 K): G(CoCH3) -0.62 (t, 3 H, 3J(PH) = 10.3 Hz), G(PCH3) 1.21 (d, 18 H, 2J(PH)= 6.9 Hz), 100 mL of pentane were combined a t -70 "C. Warming to B(CCH3) 2.20 (s, 3 HI, 6(H-2/3)3.83 (s, 1H) and 3.91 (s, 1 H), -40 "C gave a deep red solution which after 3 h was filtered 6(H-1/4) 4.81 (s, 2 H), d(Ca514)6.84-7.16 (m, 9 H). 13CNMR and reduced t o a volume of 50 mL. At -50 "C 360 mg of dark (75 MHz, THF-ds, 297 K): G(CoCH3) -22.6, G(PCH3) 18.2, 6red shining crystals was obtained (51%, not optimized); dec (C-1/2/3/4) 61.5, 62.6, 84.4, and 84.5; B(C6H514) 123.0, 128.2, pt '85 "C. Anal. Calcd for C31H39CoP2 (532.6): C, 69.91; H, 129.1,129.9,130.3, and 132.4; 6(Cquad)142.7, 143.8, and 146.7. 7.38; P, 11.64. Found: C, 69.79; H, 7.25; P, 11.58. 'H NMR Preparation of [(1-4-q)-6,6-Bis(4-chlorophenyl)fulven- (60 MHz, THF-de, 297 K): G(PCH3) 0.9 (S 18 HI, 6(H-2/3) 4.0 elmethylbis(trimethylphosphine)cobalt(I) (10). CoMe(5, 2 H), 6(H-1/4) 4.6 (s, 2 H), d(CoCa5) 6.1-6.4 (m, 5 H), (PMed4 (520 mg, 1.37 mmol) in 140 mL of pentane at -70 "C B(Cdi415) 6.8-7.3 (m, 9 H). was combined with 6,6-bis(4-chlorophenyl)fulvene(390 mg, Preparation of [ (1-4-q)-6,6-Bis(4-chlorophenyl)fulve1.30 mmol) and allowed to warm up under stirring. After 1h nelphenylbis(trimethylphosphine)cobalt(I)(15). CoPhat 20 "C the red solution was filtered and the volume reduced (PMe3)4 (500 mg, 1.14 mmol) in 40 mL of pentane and 6,6t o 30 mL in vacuo. At -20 "C 650 mg of small dark red sticks bis(4-chlorophenyl)fulvene (300 mg, 1.00 mmol) in 60 mL of was obtained (93%);mp 155-156 "C. Anal. Calcd for C25H33pentane were combined a t -70 "C and when warmed to -50 Cl&oPz (524.7): C, 57.17; H, 6.29; P, 11.81. Found: C, 56.92; "C formed a deep red solution. After 2 h filtration and H, 6.65; P, 11.59. 'H NMR (300 MHz, THF-de, 297 K): 6crystallization at -70 "C from a volume of 30 mL gave 270 (COcH3) -0.50 (t, 3 H, 3J(PH)= 9.3 Hz), G(PCH3) 1.21 (d, 18 mg of dark red shining crystals (43%, not optimized); dec pt H, 'J(PH) = 6.1 Hz), 6(H-2/3) 3.92 (s, 2 H), 6(H-1/4) 4.82 (s, 2 ~ ~ C OC, P 61.34; ~ H, 290 "C. Anal. Calcd for C ~ O H ~ ~ C(587.4): H), B(Ca.4) 7.10 (m, 8 H). NMR (75 MHz, THF-de, 297 6.00; P, 10.54. Found: C, 61.34; H, 6.26; P, 10.20. 'H NMR K): G(CoCH3) -25.3, G(PCH3) 18.0, S(C-1/2/3/4)62.9, and 84.5, (300 MHz, THF-ds, 243 K): 6(PCH3) 1.23 (d, 18 H, 2J(PH)= 6(C-5) 88.6, 6(CsH4) 128.6 and 131.2, 6(CC1) 193.2 and 195.2. Preparation of [(1-4-q)-6,6-Bis(4-methoxyphenyl)ful- 6.9 Hz), 6(H-2/3)4.04 (s, 2 H), 6(H-1/4)5.14 (s, 2 H), d(C0Ca5) 6.67-6.78 (m, 5 H), G(C&4) 7.10-7.38 (m, 8 H). venelmethylbis(trimethylphosphine)cobalt(I)(11). CoMePreparation of [( 1-4-q)-6,6-Bis(4-methoxyphenyl)ful(PMe& (600 mg, 1.58 mmol) in 50 mL of pentane and 6,6venelphenylbis(trimethylphosphine)cobalt(I) (16). CoPhbis(4-methoxypheny1)fulvene(440 mg, 1.50 mmol) in 80 mL (PMe3)d (390 mg, 0.89 mmol) in 40 mL of pentane and 6,6of pentane were combined at 20 "C. After 15 min a dark red bis(4-methoxypheny1)fulvene(260 mg, 0.88 mmol) in 60 mL solid started depositing, and after 4 h of stirring the volume of the mixture was reduced to 70 mL. The solid was filtered of pentane were combined at -70 "C and warmed up to 20 "C. and washed with 30 mL of fresh pentane. Extraction of the After 2 h the deep red solution was filtered. Crystallization solid with 80 mL of ether and crystallization from a volume of from a volume of 30 mL at -20 "C gave 290 mg of small dark 30 mL a t -20 "C afforded 720 mg of dark red shining crystals red cubes (57%); dec pt '110 "C. Anal. Calcd for C32H41(90%); mp 146-148 "C. Anal. Calcd for C Z ~ H ~ ~ C O O ~CoOzP2 P ~ (578.5): C, 66.44; H, 7.10; P, 10.70. Found: C, 66.22; (516.5): C, 62.79; H, 7.61; Co, 11.41. Found: C, 61.90; H, 7.80; H, 7.58; P, 10.54. CO, 11.72. 'H NMR (300 MHz, THF-de, 297 K): d(COcH3) Preparation of [(1-4-q)-6,6-Bis(4-(dethylamino)phe-0.60 (t, 3 H, 3J(PH) = 10.2 Hz), G(PCH3) 1.22 (d, 18 H, 2J(PH) nyl)fulvenelphenylbis(trimethylphosphine)cobalt(I) (17). = 8.2 Hz), d(OcH3) 3.70 (s, 6 H), 6(H-2/3) 3.77 (s, 2 H), 6(HCoPh(PMe& (410 mg, 0.93 mmol) in 80 mL of ether and 6,61/41 4.86 (s, 2 H), d(CsH4) 123.8 and 130.8, 6(Cquart) 139.2 and bis((dimethy1amino)phenyl)fulvene (290 mg, 0.93 mmol) in 100 156.8. mL of ether were combined a t -70 "C. After the mixture was Preparation of [(1-4-q)-6,6-Bis(4-(di"thylamino)phestirred for 3 h at -30 "C, a dark red solution was formed that nyl)fulvenelmethylbis(trimethylphosphine)cobalt(I) (12). was filtered and reduced to a volume of 30 mL. Crystallization CoMe(PMe3)r (350mg, 0.92 mmol) in 50 mL of ether and 6,6at -40 "C gave 360 mg of small dark red sticks (65%);dec pt bis(4-(dimethylamino)phenyl)fulvene(280 mg, 0.89 mmol) in '90 "C. Anal. Calcd for C ~ O H ~ ~ C (587.4): O N ~ P C, ~ 67.48; H, 100 mL of ether were combined at 20 "C t o give a red solution. 7.77; P, 10.25. Found: C, 67.56; H, 8.28; P, 10.43. 'H NMR After 2 h filtration and crystallization from a volume of 40 (300 MHz, THF-de, 213 K): G(PCH3) 1.22 (5, 18 H), G(NCH3) mL at -20 "C afforded 420 mg of dark red shining crystals 2.85 (s, 12 H), 6(H-2/3) 3.93 (s, 2 H), d(H-1/4) 5.12 (s, 2 H), (73%,not optimized);mp 165-166 "C. Anal. Calcd for C29H456(CoC&5) 6.56-6.68 (m, 5 H), 6(C&4) 7.04-7.34 (m, 8 HI. CoN2P2 (542.5): C, 64.20; H, 8.36; N, 5.16. Found: C, 64.28; Reaction of 1 with Carbon Monoxide. Complex 1 (320 H, 8.30; N, 5.19. 'H NMR (300 MHz, THF-de, 297 K): mg, 0.31 mmol) in 120 mL of ether at 20 "C was stirred under G(CoCH3) -0.68 (t, 3 H, 3J(PH)= 9.8 Hz), d(PCH3) 1.15 (s, 18 HI, G(NCH3) 2.85 (S 12 HI, a(H-213)3.80 (9, 2 H), 6(H-1/4) 4.80 1bar of CO for 18 h. The deep red solution changed to orange.
2728 Organometallics, Vol. 14, No. 6, 1995
Klein et al.
Table 1. Crystal Data and Refinement Details for 2 and 8 formula fw crystal size, mm cryst syst space group a,A
b, A
c, A
a, deg
ss, deg
T,K Dcaic,g L(Mo Ka),A p , mm-' scan mode F(000) 20 limits, deg hkl range no. of rflns collcd no. of indep rflns Rmt abs cor midmax transmissn no. of params R 1 (I > 2a(I)) wR2 GOF
2
8
C60HgiC020P6 1132.0 0.22 x 0.19 x 0.14 triclinic
CmH39CoP2 484.5 0.25 x 0.25 x 0.22 triclinic P1 8.639(2) 12.205(3) 13.626(5) 74.82(2) 73.19(2) 77.1(2) 1307.5(7) 2 293(2) 1.230 0.710 73 0.790
P1 19.432(8) 15.155(6) 14.609(5) 63.611(10) 66.240(10) 61.169(10) 3275.8(22) 2 293(2) 1.148 0.710 73 0.687 8/28 1206 5-40 -20 to 20; -15 +16; 0-16 6427 6104 0.0461 Lp, empirical 530 0.0981 0.2520 1.060
Results and Discussion Preparations. Combiningthe (cyc1opentene)cobalt(0)complex Co(C5Hd(PMe& and a 6,6-diarylfulvene compound (eq 1)in pentane either at 20 "C or at -70 "Cimmediately gives a red solution (except for 6 which and 6 are is slowly formed). Dark red crystals of 1,2,4,
R1wR ,
~ C O ( C ~ H+~ 2) L ~
/
-2
C5H8
Q
13/28
516 5-56 -10 to 11; -15 +15; 0,17
6288 6035 0.0265 )I scans 0.892/0.813 281 0.0461 0.0944 0.954
All volatile material was removed in vacuo, and the orange residue was extracted with 40 mL of pentane. From a volume of 20 mL at -20 "C 110 mg of light red crystals was obtained that was identified as 6,6-diphenylfulvene by 'H NMR (77% yield); mp 78-78.5 "C. The mother liquor contained tetracarbonyltetrakis(trimethylphosphine)dicobalt(0)12(IR). Reaction of 7 with Carbon Monoxide. Complex 7 (710 mg, 1.56 mmol) in 150 mL of ether was stirred under 1bar of CO at 20 "C. An orange solution was obtained after 1h, which after 3 h was worked up as described for 1. A total of 310 mg of 6,6-diphenylfulvene was isolated, and the mother liquor was shown to contain C O ( C O C H ~ ) ( C O ) ~ ( P(IR). M~~)~~~ X-ray Crystallography. The determination of the X-ray structures of 2 and 8 was carried out using single crystals sealed in capillaries under argon. Data for 2 were collected on a Philips PWllOO diffractometer, while for 8 a Nicolet R 3 m N diffractometer was used. Crystal data and a summary of structure refinements are collected in Table 1; atomic positional parameters for 2 are given in Tables 2 and 3 and those for 8 in Tables 4 and 5. The structure of 2 was solved by direct methods using SHELXS8622and refined on F by full-matrix least-squares techniques using SHELXL-9323with all data corrected for absorptions by DIFABS.24 Cobalt, phosphorus, and non-methyl carbon atoms were refined anisotropically and all methyl groups isotropically with H atoms fixed in idealized positions. A solvating ether molecule could be located but not fully refined due to insufficient crystal quality. The structure of 8 was solved and refined using the SHELXTL-PLUS routine.25 All non-hydrogen atoms were refined isotropically with hydrogen atoms fixed in calculated positions.26 (22) Sheldrick, G. M. Acta Crystallogr. 1990,A46, 467. (23) Sheldrick, G. M. SHELXL-93; University of Gottingen, 1993. (24) Walker, N.; Stuart, D. Acta Crystallogr. 1983,A39, 158. (25) Sheldrick, G. M. SHELXTL-PLUS Structure Determination Software Programs; Siemens Analytical X-ray Instruments Inc.: Madison, WI, 1990. (26) The X-ray crystallography study of 8 was kindly carried out by U. Floerke and H.-J. Haupt, University of Paderborn, Paderborn, FRG.
1-6
obtained that are stable in air for a few minutes, while in solution oxidative degradation is complete within seconds. Complex 3 was deposited from pentane or ether solutions as a dark red solid and on careful cooling did not form larger crystals. Complex 5 formed large crystals from ether that on drying in vacuo were transformed into a red powder. Both solids are air-sensitive. Solid compounds 1-6 are slightly soluble in pentane and progressively better soluble in ether, THF, and toluene. A slow reaction is observed with acetone, and fast decomposition occurs in chlorinated or protic solvents. IR and NMFt Spectra. Infrared spectra of 1-6 contain all bands characteristic for coordinated trimethylphosphine, while the fingerprint of the hydrocarbon ligand does not clearly indicate the type of metal coordination. The 'H NMR spectrum of 1 is representative of those for complexes 1-6. There are neither unusual shifts nor line broadenings that could be connected with a paramagnetic valence state. All proton resonances are observed where expected for a diamagnetic complex. When the temperature is lowered, one of the signals (305 K: 3.13 ppm, 2 H) splits into two singlets at 3.13 ppm (1 H) and 2.99 ppm (1H), which are assigned to the terminal allyl protons. The central allyl proton resonates at 4.31 ppm, and the fourth proton of the Cg ring experiences a high-field shift to 2.30 ppm by transformation of this ring atom into an sp3-Catom. The same pattern of lH NMR signals is observed in the spectra of complexes 2-6, but there is no coincidence of allyl proton signals at 305 K. The spectra indicate dimerization of the (fu1vene)cobalt(0) complex via C,C coupling t o give a diamagnetic dicobalt(1) compound. Proof was obtained by a singlecrystal X-ray study.
Organometallics, Vol. 14, No. 6, 1995 2729
Diarylfulvene Complexes of Cobalt(0) Table 2. Atomic Coordinates ( x lo4) and Equivalent Isotropic Displacement Parameters (A2 x 10s) for 2” atom
X
1747(1) 2673(1) 1698(2) 513(2) 2445(2) 3241(2) 1872(2) 3649(2) 2716(6) 1830(7) 1712(7) 2450(7) 3134(7) 3917(7) 4600(4) 5208(5) 5871(4) 5926(4) 5319(6) 4656(4) 4165(5) 3924(5) 4127(6) 4571(7) 4813(5) 4610(5) 6667(16) 4683(26) 1301(16) 1055(28) 1346(18) 964(31) 2668(12) 2790(38) -46( 11) -152(31) 45(23) 341(36) 551(36) - 162(21) -332(23) 2702(22) 2216(22) 3514(15)
Y
1460(2) 3815(2) -106(3) 2410(3) 1557(3) 2527(3) 5011(3) 4411(3) 2495(9) 2623(10) 1754(11) 915(9) 1287(9) 701(9) 1098(6) 659(6) 968(8) 1717(8) 2156(6) 1846(7) -467(5) -856(8) -1941(9) -2637(6) -2248(7) -1163(8) 2019(20) -3701(35) -518(20) -474(35) -627(22) -329(38) -1250(16) -1088(50) 2154(15) 3297(54) 3800(30) 3808(44) 3663(46) 2686(38) 2061(33) 2729(26) 3002(26) 940(22)
2
Ueq)
6858(2) 8999(2) 7451(3) 6722(4) 5232(3) 10234(3) 9788(3) 7953(3) 6820(8) 7134(10) 8043(10) 7918(9) 7292(8) 7249(9) 6666(7) 7188(6) 6716(8) 5723(8) 5201(6) 5672(6) 7829(8) 8919(7) 9418(7) 8827(11) 7738(10) 7239(6) 5282(20) 9377(34) 6766(22) 7158(40) 8897(21) 8818(37) 7462(18) 6886(56) 6193(15) 7423(57) 6590(41) 5766(58) 5264(50) 7938(33) 8209(30) 4228(25) 4348(26) 4838(21)
a U(eq) is defined as one-third of the trace of the orthogonalized Vi tensor.
Molecular Structure of 2. The triclinic cell of 2 contains two enantiomers; the molecule adopting an S,S configuration is shown in Figure 1. In the molecular unit each of the two tris(trimethy1phosphine)cobalt fragments is coordinated to an y3-allyl function of a hydrocarbon ligand that appears as a dimer of the pentafulvene and has become a methylidene-substituted dihydrofulvalene derivative. In spite of identical metal coordination the bond connecting the halves of the molecule does not contain a center of symmetry, possibly reflecting the centrosymmetric point group. Rather, the molecules of 2 adopt C1 symmetry because the Cg rings are twisted in a helical manner and are forced into a staggered conformation with respect to each other. This is best illustrated by a view perpendicular to the COCO vector (Figure 1). The shortest distances between atoms C(2)-C(5) and C(30)-C(33) are 3.2-3.5 A,excluding bonds between the rings. As a result of y3-allyl coordination the fulvene C5 rings are not planar and double and single C,C bonds do not alternate any longer. Only the formerly exocyclic C=C bond is still present (C(5)-C(6) = 1.33(2)8,C(33)-C(34)
Table 3. Selected Bond Lengths (A)and Angles (deg) for 2 co(l)-c(3) co(l)-c(4) Co(l)-P(l) c0(2)-c(31) C0(2)-c(32) c0(2)-P(5) Co(l)-C(2) C(l)-C(29) C(3)-C(4) C(5)-C(6) C(6)-C(7) C(29)-C(33) C(31)-C(32) C(33)-C(34) C(34)-C(41) P(2)-Co(l)-P(l) P(l)-Co(l)-P(3) P(4)- CO(2)-P( 6) C(2)-C(l)-C(5) C(5)-C(l)-C(29) C(4)-C(3)-C(2) C(6)-C(5)-C(4) C(4)-C(5)-C(l) C(5)-C(6)-C(7) C(8)-C(7)-C(6) C(14)-C(13)-C(6) C(3O)-C(29)-C(33) C(33)-C(29)-C(l) C(32)-C(31)-C(30) C(34)-C(33)-C(32) C(32)-C(33)-C(29) C(33)-C(34)-C(41)
1.937(11) 2.102(11) 2.173(4) 1.933(11) 2.101(11) 2.174(5) 1.53(2) 1.58(2) 1.39(2) 1.33(2) 1.50(2) 1.53(2) 1.42(2) 1.34(2) 1.50(2) 99.2(2) 101.7(2) 101.9(2) 101.9(9) 111.6(8) 103.8(10) 126.4(10) 103.8(9) 125.9(10) 115.3(7) 122.0(8) 101.4(9) 112.8(9) 100.4(10) 127.3(10) 104.7(9) 119.7(10)
Co(l)-C(2) Co(l)-P(2) CO(l)-P(3) C0(2)-C(30) c0(2)-P(4) c0(2)-P(6) C(1)-C(5) C(2)-C(3) C(4)-C(5) C(6)-C(13) C(29)-C(30) C(30)-C(31) C(32)-C(33) C(34)-C(35)
2.062(11) 2.158(5) 2.189(5) 2.065(11) 2.163(5) 2.199(5) 1.54(2) 1.43(2) 1.49(2) 1.50(2) 1.48(2) 1.45(2) 1.45(2) 1.51(2)
P(2)-Co(l)-P(3) 104.0(2) P ( ~ ) - C O ( ~ ) - P ( ~ )101.2(2) P(~)-CO(~)-P( 6) 102.4(2) C(2)-C(l)-C(29) 112.2(9) C(3)-C(2)-C(l) 108.8(10) C(3)-C(4)-C(5) 112.0(10) C(6)-C(5)-C(l) 129.6(10) C(5)-C(6)-C(13) 119.0(10) C(13)-C(6)-C(7) 115.1(9) C(12)-C(7)-C(6) 124.7(7) C(18)-C(13)-C(6) 117.9(8) C(30)-C(29)-C(l) 115.1(8) C(31)-C(3O)-C(29) 111.0(9) C(31)-C(32)-C(33) 113.0(10) C(34)-C(33)-C(29) 127.7(10) C(33)-C(34)-C(35) 127.2(10) C(35)-C(34)-C(41) 113.1(10)
Table 4. Atomic Coordinates ( x lo4) and Equivalent Isotro ic Displacement Parameters x 109 for 8
(1
atom
X
2393(1) 4957(1) 2518(1) lOOO(4) 96(4) 130(4) 1079(4) 1321(3) 1754(4) 2160(4) 1820(4 2200(4) 2936(4) 3294(4) 2919(4) 3344(5) 1788(4) 459(4) 478(4) 1839(4) 3177(4) 3157(4) 1882(5) 5890(5) 6529(4) 5427(4) 961(5) 2259(6) 4342(5) 2864(4)
Y.
971(1) 72(1) 2388(1) -194(3) 877(3) 970(3) -583) -915(3) -2094(3) -2883(3) -4018(3) -4777(3) -4477(3) -3366(3) -2591(3) -5324(3) -2611(2) -2419(3) -2913(3) -3627(3) -3827(3) -3339(3) -4175(3) -167(4) 736(4) -1370(3) 3650(3) 2083(4) 3085(3) 2036(3)
z
Ueq)
2315(1) 2147(1) 2953(1) 3603(2) 3235(3) 2177(3) 1899(2) 2841(2) 2953(2) 3897(2) 4200(3) 5082(3) 5727(3) 5429(3) 4549(2) 6682(3) 2070(2) 1643(3) 839(3) 416(2) 840(3) 1651(2) -467(3) 3250(3) 1073(3) 1909(3) 2723(3) 4370(3) 2479(3) 883(2)
= 1.34(2) A). C-C bonds connecting the atoms C(1)C(2), C(l)-C(5), C(29)-C(30), and C(29)-C(33) and in particular bond angles at C(1) and C(29) show values characteristic for sp3-C atoms. Both C5 rings are connected by a rather long bond (C(l)-C(29) = 1.58(2) A). Surprisingly this can be opened by simply introduc-
Klein et al.
2730 Organometallics, Vol. 14, No. 6, 1995
C
Figure 1. Molecular structure of 2 (ORTEP plot). Hydrogen atoms and phosphorus methyl groups (showing rotational disorder) are omitted for clarity. The 4-methylphenyl and phenyl groups show pairwise statistical disorder.
ing carbon monoxide ligands a t the metal (see carbonylation of 1 below). q4-Fulvene Complexes of Cobalt(1). Methyltetrakis(trimethy1phosphine)cobalt and its o phenyl analogue react with the same range of diarylfulvenes in pentane solution, liberating two phosphine ligands (eq 2). In the synthesis of phenylcobalt complexes, temper-
-2L
7-18 R'
7 8 9
10 11 12 13 14 15 16 17 18
H H CH3
c1
atures below -30 "C provide better yields, and solutions of compounds 13-17 on standing at 20 "C slowly decompose, forming inter alia biphenyl, elemental co-
Table 6. Selected Bond Lengths (deg) for 8 Co-P(l) Co-C(l) CO-c(3) Co-c(5) C(l)-C(2) C(3)-C(4) C(l)-C(5) C(6)-C(7)
2.1705(11) 2.177(3) 2.016(3) 2.517(3) 1.410(4) 1.415(4) 1.465(4) 1.464(4) 100.08(4) 106.22(9) 89.84(10) 113.03(10) 152.43(9) 141.63(7) 87.13(11) 122.90(14) 94.22(13) 108.6(3) 109.9(3) 130.6(3) 124.1(3)
(A)and Angles
Co-P(2) Co-C(2) CO-c(4) co-c(41) C(2)-C(3) C(4)-C(5) C(5)-C(6) C(6)-C(14)
2.2187(11) 2.026(3) 2.136(3) 2.016(3) 1.406(4) 1.457(4) 1.382(4) 1.494(4) 103.71(9) 142.34(10) 146.82(10) 107.13(9) 91.55(7) 94.02(11) 155.26(14) 89.77(14) 128.67(13) 106.7(3) 101.6(3) 127.8(3) 118.6(3)
balt, and fulvene. The dark red crystals of compounds 13-17 are extremely air-sensitive, in contrast to their methyl analogues, which are stable in air for several hours. Likewise, complexes 7-12 can be grown as dark red crystals with black shining surfaces. Their solubilities closely resemble those of their counterparts 1-6. As complex 12 is precipitated from pentane and proved difficult to recrystallize, a synthesis in ether or THF solvent is preferred. The IR spectra of complexes 7-12 display strong bands between 1180 and 1140 cm-' which are assigned to v(C=C) stretches of endocyclic double bonds with a characteristic bathochromic coordination shift.ll In the lH NMR spectra high-field shifts for Cs-ring protons H(l)-H(4) of 1.5-3.0 ppm confirm the presence of coordinated C=C bonds. P,H couplings of PMe3 and CoMe resonances display an angular dependence expected for (ax,eq) diene coordination in a trigonalbipyramidal geometry. This was verified by a singlecrystal X-ray study of 8. Molecular Structure of 8. The triclinic unit cell of 8 contains two molecules of the same conformation
Diarylfulvene Complexes of Cobalt(0)
Organometallics, Vol. 14, No. 6, 1995 2731
Figure 2. Molecular structure of 7 (ORTEP plot).
(Figure 2). In the mononuclear complex a CoMe(PMe3h group is v4-coordinated t o the endocyclic C=C bonds of the pentafulvene. The fifth atom of the C5 ring is held at a nonbonding distance (c(5)-co = 2.517(3) A) and is bent out of the plane C(l)C(2)C(3)C(4)and away from the metal at an angle of 19.8"with respect to that plane. Bond distances and angles are as expected and, for instance, closely resemble the structure of a cyclopentadienylcobalt(1) complex containing a diarylfulvene ligand.27 If we define the atoms C(41), P(1), and P(2) and the midpoints of the bonds C(l)-C(2) and C(3)-C(4) as ligand positions, the geometry around the cobalt is trigonal bipyramidal. P(1), P(2), and the midpoint C(3)-C(4), occupy equatorial positions, and the CoMe group is in one of the axial positions. Certainly in the other axial position the midpoint C(l)-C(2) deviates from an ideal trigonal-bipyramidal geometry by an angle of 45.4", which is due to the rigid geometry of the fulvene ring. Bond lengths and angles are thus as expected for o-methyl, trimethylphosphine, and diene coordination. Reactions of 1 and 7 with CO. In order to learn how ligand properties are affected by other strong n-acceptor ligands, carbonylation reactions under ambient conditions have been conducted with the representative complexes 1 and 7. In ether solutions under 1 bar of CO both reactions proceed within a few hours as indicated by the orange color of free fulvene (eqs 3 and 4). From both solutions 6,6-diphenylfulvene is crystallized in almost quantitative yield. The cobalt is transformed into a well-known derivative[13]of C02(CO)8. The formal reduction of cobalt in complex 1 is balanced by the oxidative C,C cleavage of the dihydrofulvalene system. Carbonylation of 7 smoothly transforms the methylcobalt moiety into the expected acetylcobalt(1) compound.13 No carbonylcobalt compound containing a hydrocarbon ligand was obtained. (27) Wadepohl, H.; Pritzkow, H. Acta Crystallogr. 1991,C47, 2061.
,%"5
C6H5 H5C6
2b
+
CO2(CO),L, + 2 L (3)
Conclusion
Ligand substitution reactions in d9 (trimethylphosphinelcobalt complexes involving 6,6-diarylfulvenes induce spin-spin interactions of two metals and result in C,C coupling reactions between two fulvene C5 rings. While there are numerous reports on reactions of (trimethy1phosphine)cobalt complexes with isolated, conjugated, or cumulated C=C functions providing n-coordinated paramagnetic metal systems without indicating transfer of electron density from the cobalt onto the n-ligands,lr2,28using fulvene ligands substantial delocalization of unpaired electron density from the metal onto the n-perimeter of the cross-conjugated system is observed for the first time. Single-electron
2732
Organometallics, Vol. 14, No. 6,1995
Klein et al.
transfer appears to be the key step, which is followed by reductive dimerization and coordination of the oxidized metal species. This reaction sequence is reversed by simply admitting carbonyl ligands to the metal. Radical intermediates A and B can be envisaged t o take part in the regioselective C,C-coupling reaction between the two C(4) positions. The C(6) position in a C
Ph
L3C0
Y Ph
-45 A
Ph
YPh C0L2
B
Pentafulvenes appear to be ideal reactants that can activate the unpaired electron of zerovalent cobalt for metal-controlled radical reactions in the periphery of the hydrocarbon ligand. The absence of carbonyl ligands is essential.
B
radical dimerization reaction would be subject to steric hindrance similar t o that of the triphenylmethyl radical C (B is shown without the metal in this representation). (28)(a)Agnes, G.;Bassi, W., Benedicenti, C.; Intrito, R.; Calcaten-a, M.; Santini, G. J . Organomet. Chem. 1977,129,401. (b) Woode, K.A.; Bart, J. C. J.; Calcaterra, M.; Agnes, G. Organometallics 1983,2,627. (c) Klein, H.-F.; Ellrich, K.; Lamac, S.; Lull, G.; Zsolnai, L.; Huttner, G. 2.Naturforsch. 1985,B40,1377. (d)Klein, H.-F.; Helwig, M.; Koch, U.; Tadic, M.; Kriiger, C.; Hofmann, P. 2.Naturforsch. 1988,B43,1427.
Acknowledgment. Financial support of this work by the Deutsche Forschungsgemeinschaft and Fonds der Chemischen Industrie is gratefully acknowledged. Supplementary Material Available: Tables of bond lengths and angles, anisotropic displacement parameters, and atomic coordinates for compounds 2 and 8 (19 pages). Ordering information is given on any current masthead page. OM940683P
