Reactivity of 2,3-bis(2-pyridyl)pyrazine with [Re₂(CO)₈(CH₃CN)₂]: Molecular structures of [Re₂(CO)₈(C₁₄H₁₀N

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• 作者：Rubé ; n A. Machado ; Marí ; a Cristina Goite ; David Rivillo ; Ysaura De Sanctis ; Alej ; ro J. Arce ; Antony J. Deeming ; Lindora D’ ; Ornelas ; Anibal Sierralta ; Reinaldo Atencio ; Teresa Gonzá ; l
• 关键词：Rhenium carbonyls ; α ; -diimines ; Crystal structures ; Pyridine ; Pyrazine
• 刊名：Journal of Organometallic Chemistry
• 出版年：2007
• 期刊代码：64_0022328x
• 类别：ch
• 出版时间：15 January 2007
• 卷：692
• 期：4
• 页码：894-902
• 文件大小：628 K

摘要

The reaction of the labile compound [Re₂(CO)₈(CH₃CN)₂] with 2,3-bis(2-pyridyl)pyrazine in dichloromethane solution at reflux temperature afforded the structural dirhenium isomers [Re₂(CO)₈(C₁₄H₁₀N₄)] (ong>1ong> and ong>2ong>), and the complex [Re₂(CO)₈(C₁₄H₁₀N₄)Re₂(CO)₈] (ong>3ong>). In ong>1ong>, the ligand is σ,σ′-N,N′-coordinated to a Re(CO)₃ fragment through pyridine and pyrazine to form a five-membered chelate ring. A seven-membered ring is obtained for isomer ong>2ong> by N-coordination of the 2-pyridyl groups while the pyrazine ring remains uncoordinated. For ong>2ong>, isomers ong>2aong> and ong>2bong> are found in a dynamic equilibrium ratio [ong>2aong>]/[ong>2bong>] = 7 in solution, detected by ¹H NMR (−50 °C, CD₃COCD₃), coalescence being observed above room temperature. The ligand in ong>3ong> behaves as an 8e-donor bridge bonding two Re(CO)₃ fragments through two (σ,σ′-N,N′) interactions. When the reaction was carried out in refluxing tetrahydrofuran, complex [Re₂(CO)₆(C₁₄H₁₀N₄)₂] (ong>4ong>) was obtained in addition to compounds ong>1ong>–ong>3ong>. The dinuclear rhenium derivative ong>4ong> contains two units of the organic ligand σ,σ′-N,N′-coordinated in a chelate form to each rhenium core. The X-ray crystal structures for ong>1ong> and ong>3ong> are reported.