Evidence for correlated rotation and diastereoisomer discrimination in (η4-diene)Fe(CO)2L complexes: the crystal and solution structures of (cyclohexadiene)Fe(CO)2P(o-tolyl)3 and (cycloheptadiene)Fe(CO)2(+)-PPh2(neomenthyl)

Howell, James A. S.; Palin, Michael G.; Tirvengadum, Marie-Claire; Cunningham, Desmond; McArdle, Patrick; Goldschmidt, Zeev; Gottlieb, Hugo E.

doi:10.1016/0022-328x(91)80056-p

Cited by 11 publications

(4 citation statements)

References 42 publications

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“…It should be noted that the basal-phosphine conformers 25B and 25B ‘ (Scheme ) are diastereomeric , and therefore, a unique 31 P NMR shift should be observed for each rotamer. The observation of four signals at lower temperature may be due to rotamers about the Fe−P bond for each of the individual conformers . It was not possible to assign which diastereomeric rotomer was the major species.…”

Section: Resultssupporting

confidence: 83%

Reactivity of (Bicyclo[5.1.0]octadienyl)iron(1+) Cations: Application to the Synthesis of cis-2-(2‘-Carboxycyclopropyl)glycines

Wallock

Donaldson

2004

J. Org. Chem.

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The addition of carbon and heteroatom nucleophiles to (bicyclo[5.1.0]octadienyl)Fe(CO)(2)L(+) cations 5 or 8 (L = CO, PPh(3)) generally proceeds via attack at the dienyl terminus on the face of the ligand opposite to iron to generate 6-substituted (bicyclo[5.1.0]octa-2,4-diene)iron complexes (11 or 13). In certain cases, these products are unstable with respect to elimination of a proton and the nucleophilic substituent to afford (cyclooctatetraene)Fe(CO)(2)L (4 or 7). Decomplexation of 13f, arising from addition of phthalimide to 8, gave N-(bicyclo[5.1.0]octa-3,5-dien-2-yl)phthalimide (19). Oxidative cleavage of 19 (RuCl(3)/NaIO(4)) followed by esterification gave the cyclopropane diester 22, which upon hydrolysis gave cis-2-(2'-carboxycyclopropyl)glycine (CCG-III, 18) (eight steps from 4, 43% overall yield). This methodology was also utilized for preparation of stereospecifically deuterated CCG-III (d-18) and optically enriched (-)-18. Deprotonation of 22 resulted in cyclopropane ring opening to afford the benzoindolizidine (23).

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Section: Resultssupporting

confidence: 83%

Reactivity of (Bicyclo[5.1.0]octadienyl)iron(1+) Cations: Application to the Synthesis of cis-2-(2‘-Carboxycyclopropyl)glycines

Wallock

Donaldson

2004

J. Org. Chem.

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“…By direct analogy we can evaluate the structural parameters for 1,3-cyclohexadiene complexes to asses the importance of η 4 -1,3-cyclohexadiene and (σ 2 ,π-bonded) metallanorbornene bonding pictures (Scheme ). In Table are collected the values of θ, Δ d , and Δ l for the compounds obtained in this study and for other derivatives of 1,3-cyclohexadiene contained in the Cambridge Crystallographic Database. − It can be seen that the new Group 5 metal compounds have the largest values for θ (most negative value of Δ d Figure ) implying that these molecules may best be represented by the (σ 2 , π-bonded) metallanorbornene bonding model ( B ). A study of related Group 5 metal η 6 -arene complexes has identified a metallanorbonadiene bonding description as reasonable …”

Section: Resultsmentioning

confidence: 97%

Coordination and Hydrogenation of 1,3-Cyclohexadiene by Niobium and Tantalum Aryl Oxide Compounds: Relevance to Catalytic Arene Hydrogenation

et al. 1997

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The sodium amalgam (2 Na per M) reduction of hydrocarbon solutions of the chloro, aryl oxide compounds [M(OC6H3Pri 2-2,6)2Cl3]2 (1) and [M(OC6H3Pri 2-2,6)3Cl2] (2) (a, M = Nb; b, M = Ta) in the presence of 1,3-cyclohexadiene leads to formation of the η4-cyclohexadiene derivatives [M(OC6H3Pri 2-2,6)2Cl(η4-C6H8)] (3) and [M(OC6H3Pri 2-2,6)3(η4-C6H8)] (4). Spectroscopic studies of compounds 3 and 4 show in all cases a strongly bound cyclohexadiene ligand which does not readily undergo displacement (NMR) with added reagents such as PMe2Ph and cyclohexene. Single crystal X-ray diffraction analyses of 3a and the isomorphous pair 4a and 4b show in all three cases a geometry about the metal center best described as three-legged piano stool. Compound 4a will catalyze the disproportionation of 1,3-cyclohexadiene into cyclohexene and benzene as well as the hydrogenation of 1,3-cyclohexadiene and cyclohexene into cyclohexane. Mechanistic studies clearly show that cyclohexene is not released during the conversion of 1,3-cyclohexadiene to cyclohexane catalyzed by 4a. In contrast, solutions of 3a will convert 1,3-cyclohexadiene slowly to cyclohexene prior to conversion to cyclohexane. The addition of 1,3-cyclohexadiene to the trihydride compounds [Ta(OC6H3Cy2-2,6)2(H)3(PMe2Ph)2] and [Ta(OC6HPh2-3,5-Cy2-2,6)2(H)3(PMe2Ph)2] leads to the interesting products [Ta(OC6H3Cy2-2,6)2(η1-C6H10-η4-C6H7)] (5) and [Ta(OC6HPh2-3,5-Cy2-2,6)2(η1-C6H10-η4-C6H7)] (6) which, based upon structural studies of 5 contain a partially hydrogenated non-Diels−Alder dimer of 1,3-cyclohexadiene. The addition of 1,3-cyclohexadiene to the dihydride compounds [Ta(OC6H3Pri 2-2,6)2(Cl)(H)2(PMe2Ph)2] and [Ta(OC6H3But 2-2,6)2(Cl)(H)2(PMe2Ph)] leads to the dehydrogenation product [Ta(OC6H3Pri-η2-CMeCH2)(OC6H3Pri 2-2,6)(Cl)(PMe2Ph)2] (7) and the cyclohexyl compound [Ta(OC6H3But-CMe2CH2)(OC6H3But 2-2,6)(Cl)(C6H11)] (8), respectively. The mechanistic implications of these stoichiometric and catalytic reactions are discussed. Crystal data for 3a at 20°C: NbClO2C30H42. M = 563.03, space group P nma (no. 62), a = 12.237(1), b = 21.633(1), c = 10.883(2) Å, V = 2881.0(9) Å3, D c = 1.298 g cm-3, Z = 4; for 4a at 20 °C: NbO3C42H59. M = 704.84, space group P21/c (no. 14), a = 11.562(1), b = 16.117(2), c = 21.914(3) Å, β = 103.69(1)°, V = 3967(2) Å3, D c = 1.180 g cm-3, Z = 4; for 4b at −57 °C: TaO3C42H59. M = 792.88, space group P21/c (no. 14), a = 11.452(2), b = 16.175(3), c = 21.765(3) Å, β = 103.52(1)°, V = 3919(2) Å3, D c = 1.343 g cm-3, Z = 4; for 5 at 20 °C: TaO2C48H67. M = 857.02, space group P21 (no. 4), a = 10.559(9), b = 15.828(10), c = 13.266(12) Å, V = 2095(6) Å3, D c = 1.358 g cm-3, Z = 2.

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“…Other inorganic and organometallic systems studied for dynamic gearing and hindered rotations include tetrakis(pyridine)ruthenium(II) complexes, iron-diene complexes, osmium clusters, , bulky silanes, − and chiral arylamido aluminates …”

Section: 18 Gearing In Organometallic and Inorganic Systemsmentioning

confidence: 99%

Artificial Molecular Rotors

et al. 2005

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Evidence for correlated rotation and diastereoisomer discrimination in (η4-diene)Fe(CO)2L complexes: the crystal and solution structures of (cyclohexadiene)Fe(CO)2P(o-tolyl)3 and (cycloheptadiene)Fe(CO)2(+)-PPh2(neomenthyl)

Cited by 11 publications

References 42 publications

Reactivity of (Bicyclo[5.1.0]octadienyl)iron(1+) Cations: Application to the Synthesis of cis-2-(2‘-Carboxycyclopropyl)glycines

Reactivity of (Bicyclo[5.1.0]octadienyl)iron(1+) Cations: Application to the Synthesis of cis-2-(2‘-Carboxycyclopropyl)glycines

Coordination and Hydrogenation of 1,3-Cyclohexadiene by Niobium and Tantalum Aryl Oxide Compounds: Relevance to Catalytic Arene Hydrogenation

Artificial Molecular Rotors

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