Dihapto cyclobutadienoid transition metal complexes. Preparation of .eta.2-1,2-benzocyclobutadiene-.eta.5-cyclopentadienyldicarbonyliron hexafluorophosphate

Abstract

Der durch Behandlung des zweikernigen trans‐Fe‐Komplexes (I) mit Tritylhexafluorophosphat dargestellte Titelkomplex (II) ist das erste Beispiel eines Komplexes mit Dihaptocyclobutadienoid‐Liganden; ein analoges Zwischenprodukt wird bei der oxidativen Zersetzung von Tetrahaptocyclobutadienoid‐tricarbonyl‐Fe angenommen.

Metal assisted carbon-carbon bond formation. Addition of carbon nucleophiles to dicarbonyl .eta.5-cyclopentadienyl(olefin)iron cations

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A new carbon-carbon bond synthesis is described, which involves the addition of carbon nucleophiles to olefins, activated as dicarbonyl n5-cyclopentadienyl(olefin)iron cations (10,13,14). Enolates derived from malonates, acetoacetates, cyanoacetates, and nitromethane as well as enamines of isobutyraldehyde, cyclopentanone, and cyclohexanone have been condensed with a number of such olefin complexes including those of ethylene, propylene, styrene, butadiene, cyclopentene, cyclohexene, and aliene.

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“…Furthermore, nucleophilic addition to polyene and polyenyl metal complexes has generally been observed to take place trans to the metal-ligand bond. [3][4][5][6][7][8][9][10][11] Accordingly a similar course of reaction has been assumed to apply to all addition reactions reported here.…”

“…5.76 (t, 2,7 = 6.5 Hz, 7-CH2), 5.28 8.75 (d, 7 = 6.5 51.46 51.49 Hz, a-CH3) 6.5-6.9 (d and t, 7-CH, both isomers), 7.4-8.5 (m, a and ß 5. .75 (t, 1, Jaa' = 7 'ß = 10 Hz,a-CH2), 8.15 (dd, 1, Jaa' = 10,7ap= 2 Hz, a-CH2), 10 Hz, a-CH2), 8.3 (dd, 1, Jaa' = 10, 7 'ß = 2.5 Hz, a-CH2), 7.5 (m, 1, /3-CH), 6.76 (d, 1,7 = 9 Hz, CH(COOMe)2), 6.46, 6.38 (2 s, 6, OCHA, 5.24 (s, 5, Cp), 4.5-5.3 (m, 7.5-8.7 (m, 8, CH, CHJ, 6.53 (d, 1,7= 5.5 54.00 54.04 Hz, CH(COOMe)J, 6.44, 6.42 (2 s, 6, OCH,), 5.28 (olefin) cations. Both of these complexes proved to be excellent substrates, affording high yields of adducts (15 and 16) as amber, air-stable oils with a number of stabilized enolates.…”

.eta.2 Cyclobutadienoid transition metal complexes. Generation and trapping of a cationic .eta.2-cyclobutadiene iron complex

“…Although complex 4 fails to react with cyclopentadiene in methylene chloride at 25°over a 4-hr period, a rapid reaction ensues when a methylene chloride solution of 4 is added to a mixture of silver hexafluorophosphate and excess cyclo-Table I. 1 H NMR and Ir for New Complexes0 4 Nmr (CS2)t 3.72 (m,& 1, H'),4.37 (m,6 ***101, 2), 5.18 (s, 5, Cp, 5.59 (mb 1, 3), 6.17 Nmr (CD3COCD3)t 3.60 (m, 2, '), 4.20 (s, 5, Cp), 4.38 diphenylisobenzofuran and cyclobutadiene.8 When a methylene chloride solution of silver hexafluorophosphate is slowly added to a methylene chloride solution of 4 at -78°, the binuclear syn-tricyclooctadiene complex 10 is obtained in 29% yield. Treatment of 10 with NaCp(CO)2Fe affords the syn-tricyclooctadiene 11.9 If 4 is added to a solution of silver hexafluorophosphate, a single uncharacterized product is obtained.…”

.eta.2-Cyclobutadienoid transition metal complexes. Preparation and characterization of a binuclear complex possessing a bridging cyclobutadiene ligand

“…(s, 5, Cp), 4.37 (m,6 1, H3), 3.72 (m,6 1, H4); ir 2000, 1950 cm-1 (CsO) 6 Nmr (CD3N02) 4.53 (s, 4, H), 4.26 (s, 10, Cp); ir 2080, 2040 cm-1 (C=0) 7Nmr (CS2) r 6.45 (s, 3, OCH3), 5.17 (s, 5, Cp),4.79 (d, 1,1, 2 = 15 Hz),3.27 (m, 2, H2 and 3, .3 = 10.5 Hz), 2.21 (d, 1, 4, .4 = 15 Hz); ir 2000, 1938 cm-1 (C=0) 8 Nmr (CD3)2CO r 6.57 (m,6 1, H4), 5.46 (m,6 1, H3), 4.98 (m,6 1, H2), 4.69 (s, 5, Cp), 4.23 (s, 5, Cp1),3.20 (m,6 1, H1); ir2060, 2025, 2000, 1944 cm-1 (C=0) " All new compounds gave satisfactory analyses for carbon and hydrogen. 6 Narrow multiplet.…”