Metallocenes as reaction intermediates

Grebenik, Peter D.; Grinter, R.; Perutz, Robin N.

doi:10.1039/cs9881700453

Cited by 31 publications

(50 citation statements)

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“…In the solid state, (C 5 H 5 ) 2 Mn is a chain polymer quite unlike the typical sandwich structure of D 5h and D 5d symmetry, 4 although in gas phase Cp 2 Mn has a sandwich structure like Cp 2 Fe. 5,6 As originally reported, the magnetic behavior of Cp 2 Mn was not readily understood, until its polymeric structure was determined.…”

Section: Introductionmentioning

confidence: 99%

Supramolecular Catalysis of Orthoformate Hydrolysis in Basic Solution: An Enzyme-Like Mechanism

2008

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Abstract. Magnetic susceptibility measurements and X-ray data confirm that tert-butyl substituted manganocenes [(Me 3 C) n C 5 H 5-n ] 2 Mn (n= 1, 2) follow the trend previously observed with the methylated manganocenes, i.e., electron donating groups attached to the Cp ring stabilize the low-spin (LS) electronic ground state relative to Cp 2 Mn and exhibit higher spin-crossover (SCO) temperatures.However, introducing three CMe 3 groups on each ring gives a temperature invariant high-spin (HS) state manganocene. The origin of the high-spin state in [1,2,4-(Me 3 C) 3 C 5 H 2 ] 2 Mn is due to the significant bulk of the [1,2,4-(Me 3 C) 3 C 5 H 2 ] -ligand, which is sufficient to generate severe inter-ring steric strain that prevents the realization of the low-spin state. Interestingly, the spin transition in [1,3-(Me 3 C) 2 C 5 H 3 ] 2 Mn is accompanied by a phase transition resulting in a significant irreversible hysteresis (∆T c = 16 K). This structural transition was also observed by extended X-ray absorption fine-structure (EXAFS) measurements. Magnetic susceptibility studies and X-ray diffraction data on SiMe 3 substituted 2 manganocenes [(Me 3 Si) n C 5 H 5-n ] 2 Mn (n= 1, 2, 3) show high-spin configuration in these cases. Although tetra-and hexasubstituted manganocenes are high-spin at all accessible temperatures, the disubstituted manganocenes exhibit a small low-spin admixture at low temperature. In this respect it behaves similarily to [(Me 3 C)(Me 3 Si)C 5 H 3 ] 2 Mn, which has a constant low-spin admixture up to 90 K and then gradually converts to high-spin. Thermal spin-trapping can be observed for [(Me 3 C)(Me 3 Si)C 5 H 3 ] 2 Mn on rapid cooling.

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Section: Introductionmentioning

confidence: 99%

Supramolecular Catalysis of Orthoformate Hydrolysis in Basic Solution: An Enzyme-Like Mechanism

2008

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“…Increasing rotation of the carbinol about the C-C bond results in increasing stability. In McCH(OH)[r| 6 -Ph(ML,,)] (ML,, = Cr(CO) 3 and Co 4 (CO) 9 ), only intramolecular bonding is found. 132 A new type of hydrogen bond, between McH and 4-XC 6 H 4 OH (X = F, NO 2 ), was indicated by very weak absorptions shown by CC1 4 solutions of the components at about 200 cm" 1 from the normal v(OH).…”

Section: A-metallocenecarbinolsmentioning

confidence: 94%

“…29 The first metallocenes containing the C 5 F 5 ligand are Ru(r|-C 5 Me 4 R)(r|-C 5 F 5 ) (R = Me or Et), prepared by flash vacuum pyrolysis of Ru(T!-C 5 Me 4 R)(Ti 6 -C 6 F 5 O). 30 Reactions between [Ru(NCMe) 3 Cp*] + or [RuCl 2 (nbd)] /( and Li [C 4 Me 4 N] afforded the first azaruthenocenes, RuCp*(r|-C 4 Me 4 N) and Ru(r|-C 4 Me 4 N) 2 , respectively. The heterocyclic group resisted r| 5 …”

Section: Introductionmentioning

confidence: 99%

“…Reviews have dealt with the chemistry of ruthenocene and osmocene between 1981 and 1985, 1 a-metallocenylcarbonium ions (the latter also contains a useful summary of the properties and reactions of MCp* 2 ), 2 metallocenes as reaction intermediates, 3 metallocenylphosphazene chemistry 4 and radiochemistry. 5 The following abbreviations and notation are used: Me = MCp(t|-C 5 H 4 -); Me" = M(TJ-C 5 H 4 -) 2 (i.e., l,l'-disubstituted); Me* = MCp*(t|-C 5 Me 4 CH 2 -); for Me, read Re and Oc for M = Ru and Os, respectively; Cp* is used where both Cp and Cp* compounds have been reported; Fv = fulvalenyl (Tf:Ti 5 -C I O H 8 ); f l u = fluorenyl (ri 5 -C 13 H 7 ); ind = indenyl (T| -C 9 H 7 ).…”

Section: Introductionmentioning

confidence: 99%

“…A similar reaction with OsCl 4 gave a low yield of a labile osmocene derivative of uncertain stereochemistry. 26 Similarly, the polycyclic ruthenocene (5) was obtained from [Ru(NCMe) 3 Other reactions which have resulted in the formation of metallocenes include the gas-phase pyrolysis of the open-chain M(r| 5 -2,4-Me 2 C 5 H 5 ) 2 (at 450 °C for Ru, 500 °C for Os) to give pale yellow M(r| 5 -2,4-Me 2 C 5 H 5 )(r|-l,3-Me 2 C 5 H 3 ) in high conversion by a disrotatory electrocyclic ring closure. At 500 °C, the ruthenium complex undergoes further reaction to Ru(r|-l,3-Me 2 C 5 H 3 ) 2 .…”

Section: Introductionmentioning

confidence: 99%

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