Formation of Gold(III) Alkyls from Gold Alkoxide Complexes
| Autor: | Manfred Bochmann, Isabelle Chambrier, David L. Hughes, Julio Fernandez-Cestau, Dragoş-Adrian Roşca, Peter H. M. Budzelaar |
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| Přispěvatelé: | Chambrier, I., Roşca, D., Fernandez Cestau, J., Hughes, D. L., Budzelaar, Petrus Henricus Maria, Bochmann, M. |
| Jazyk: | angličtina |
| Rok vydání: | 2017 |
| Předmět: |
Tris
Period (periodic table) 010405 organic chemistry Chemistry Stereochemistry Radical Organic Chemistry Methoxide 010402 general chemistry 01 natural sciences Medicinal chemistry Phosphorane Article 0104 chemical sciences Inorganic Chemistry chemistry.chemical_compound Alkoxide Physical and Theoretical Chemistry Benzene Phosphine |
| Zdroj: | Organometallics |
| ISSN: | 1520-6041 0276-7333 |
| Popis: | The gold(III) methoxide complex (C∧N∧C)AuOMe (1) reacts with tris(p-tolyl)phosphine in benzene at room temperature under O abstraction to give the methylgold product (C∧N∧C)AuMe (2) together with OP(p-tol)3 ((C∧N∧C) = [2,6-(C6H3tBu-4)2pyridine]2−). Calculations show that this reaction is energetically favorable (ΔG = −32.3 kcal mol−1). The side products in this reaction, the Au(II) complex [Au(C∧N∧C)]2 (3) and the phosphorane (p-tol)3P(OMe)2, suggest that at least two reaction pathways may operate, including one involving (C∧N∧C)Au• radicals. Attempts to model the reaction by DFT methods showed that PPh3 can approach 1 to give a near-linear Au−O−P arrangement, without phosphine coordination to gold. The analogous reaction of (C∧N∧C)AuOEt, on the other hand, gives exclusively a mixture of 3 and (p-tol)3P(OEt)2. Whereas the reaction of (C∧N∧C)AuOR (R = But, p-C6H4F) with P(p-tol)3 proceeds over a period of hours, compounds with R = CH2CF3, CH(CF3)2 react almost instantaneously, to give 3 and OP(ptol) 3. In chlorinated solvents, treatment of the alkoxides (C∧N∧C)AuOR with phosphines generates [(C∧N∧C)Au(PR3)]Cl, via Cl abstraction from the solvent. Attempts to extend the synthesis of gold(III) alkoxides to allyl alcohols were unsuccessful; the reaction of (C∧N∧C)AuOH with an excess of CH2 CHCH2OH in toluene led instead to allyl alcohol isomerization to give a mixture of gold alkyls, (C∧N∧C)AuR′ (R′ = −CH2CH2CHO (10), −CH2CH(CH2OH)OCH2CHCH2 (11)), while 2-methallyl alcohol affords R′ = CH2CH(Me)CHO (12). The crystal structure of 11 was determined. The formation of Au−C instead of the expected Au−O products is in line with the trend in metal−ligand bond dissociation energies for Au(III): M−H > M−C > M−O. |
| Databáze: | OpenAIRE |
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