“…With the pentamethylcyclopentadienyl ligand, half-sandwich complexes of cobalt(II) have been isolated as dimers. However, in the presence of phosphines, or pyridine as external donors, it is possible to isolate compounds of the type [CpCoL 2 ] + or CpCoLX (L = phosphine, X = halogen). , We deprotonated the functionalized cyclopentadiene 2 with n-BuLi and obtained the lithium salt 10 , which was treated with CoCl 2 in tetrahydrofuran at room temperature (Scheme ). 2 Preparation of Co I and Co III Complexes Starting with the Quinoline-Substituted Cyclopentadiene 1 3 Preparation of the Cobalt(II) Half-Sandwich Complex 11…”
Reaction of 2-lithio-N,N-dimethylaniline with 2,3,4,5-tetramethylcyclopentenone yields 1-[2-(N,N-dimethylaminophenyl)-2,3,4,5-tetramethylcyclopentadiene (2). As in 1-(8-quinolyl)-2,3,4,5-tetramethylcyclopentadiene (1), the N-donor is connected to the Cp ring by a rigid C 2 spacer. Co 2 (CO) 8 reacts with 1 or 2 to give the Co I -dicarbonyl half-sandwich complexes 7 and 3, respectively. Irradiation leads to the binuclear complexes 4 and 8 with a Co-Co double bond. Oxidation of 3 or 7a is possible with iodine. Whereas 7a directly forms the Co III complex 9 with coordination of the quinoline to the metal, 3 yields the monocarbonyldiiodo complex 5. Upon gentle heating in dichloromethane, 5 loses carbon monoxide to give the cobalt complex 6, displaying intramolecular nitrogen coordination. Reaction of the dimethylanilinesubstituted cyclopentadienide 10 with CoCl 2 yields the Co II complex 11. The Co III complex 6 and the Co II complex 11 were treated with methylaluminoxane (MAO) and gave low-activity catalysts for the polymerization of ethylene.
“…With the pentamethylcyclopentadienyl ligand, half-sandwich complexes of cobalt(II) have been isolated as dimers. However, in the presence of phosphines, or pyridine as external donors, it is possible to isolate compounds of the type [CpCoL 2 ] + or CpCoLX (L = phosphine, X = halogen). , We deprotonated the functionalized cyclopentadiene 2 with n-BuLi and obtained the lithium salt 10 , which was treated with CoCl 2 in tetrahydrofuran at room temperature (Scheme ). 2 Preparation of Co I and Co III Complexes Starting with the Quinoline-Substituted Cyclopentadiene 1 3 Preparation of the Cobalt(II) Half-Sandwich Complex 11…”
Reaction of 2-lithio-N,N-dimethylaniline with 2,3,4,5-tetramethylcyclopentenone yields 1-[2-(N,N-dimethylaminophenyl)-2,3,4,5-tetramethylcyclopentadiene (2). As in 1-(8-quinolyl)-2,3,4,5-tetramethylcyclopentadiene (1), the N-donor is connected to the Cp ring by a rigid C 2 spacer. Co 2 (CO) 8 reacts with 1 or 2 to give the Co I -dicarbonyl half-sandwich complexes 7 and 3, respectively. Irradiation leads to the binuclear complexes 4 and 8 with a Co-Co double bond. Oxidation of 3 or 7a is possible with iodine. Whereas 7a directly forms the Co III complex 9 with coordination of the quinoline to the metal, 3 yields the monocarbonyldiiodo complex 5. Upon gentle heating in dichloromethane, 5 loses carbon monoxide to give the cobalt complex 6, displaying intramolecular nitrogen coordination. Reaction of the dimethylanilinesubstituted cyclopentadienide 10 with CoCl 2 yields the Co II complex 11. The Co III complex 6 and the Co II complex 11 were treated with methylaluminoxane (MAO) and gave low-activity catalysts for the polymerization of ethylene.
“…with t Bu groups in the 3 position) is the tetrahedral geometry enforced . While Cp tends to the sandwich compound (cobaltacene), examples with the more strongly electron donating Cp* do show some tendency to form half-sandwich motifs in [Co(Cp*)(py)Cl] and [Co(Cp*)(μ-Cl)] 2 , where coordination expansion is also observed. It would appear that the structures obtained in these systems are driven by the electron donor capacity of the ligands, and this assertion is supported by the electrochemical data.…”
Reaction of sodium hydrotris(methimazolyl)borate (NaTm(Me)) with cobalt halides leads to the formation of paramagnetic pseudotetrahedral [Co(Tm(Me))X] (X = Cl, Br, I), of which the bromide has been crystallographically characterized. Mass spectrometry reveals the presence of higher molecular weight fragments [Co(Tm(Me))(2)](+) and [Co(2)(Tm(Me))(2)X](+) in solution. Aerial oxidation in donor solvents (e.g. MeCN) leads to formation of the [Co(Tm(Me))(2)](+) cation, which has been crystallographically characterized as the BF(4)(-), ClO(4)(-), Br(-), and I(-), salts. Attempts to prepare the mixed sandwich complex, [Co(Cp)(Tm(Me))](+), resulted in ligand decomposition to yield [Co(mtH)(3)I]I (mtH = 1-methylimidazole-2-thione), but with the more electron donating methylcyclopentadienyl (Cp(Me)) ligand, [Co(Cp(Me))(Tm(Me))]I was isolated and characterized. Electrochemical measurements reveal that the cobalt(III) Tm(Me) complexes are consistently more difficult to reduce than their Tp and Cp congeners.
“…In order to evaluate this, enantiopure 9 and 10 were synthesized (Scheme ). For the synthesis of 9 , compound 16a was reacted with succinic anhydride in the presence of AlCl 3 to give the ferrocenyl ketone 17a . Reduction of the ketone with Zn/HgCl 2 resulted in compound 18a .…”
Section: Resultsmentioning
confidence: 99%
“…AlCl 3(3.195 g, 23.96 mmol) and CH 2 Cl 2 (30 mL) were added. Compound 16a11 (5.113 g, 19.97 mmol) in CH 2 Cl 2 (50 mL) was then added dropwise via a cannula. The solution turned dark brown.…”
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