Synthesis and redox chemistry of cycloheptatrienyl molybdenum carbon-chain complexes featuring diimine support ligands: [Mo{(CC)_nCCR}(R¡äNCH-CHNR¡ä)(¦Ç-C₇H₇)], (n?=?0 or 1)

详细信息    查看全文

• 作者：Huriyyah A. Alturaifi ; James Faulkner ; James Raftery ; Floriana Tuna ; David Collison ; Mark W. Whiteley
• 关键词：Molybdenum ; Cycloheptatrienyl ; Alkynyl ligand ; Diimine ligand ; Redox chemistry
• 刊名：Journal of Organometallic Chemistry
• 出版年：2013
• 出版时间：15 November, 2013
• 年：2013
• 卷：745-746
• 期：Complete
• 页码：251-257
• 全文大小：480 K

文摘

The alkynyl complexes [Mo(CCR)(R¡ä-dab)(¦Ç-C₇H₇)] (dab?=?diazabutadiene; R¡ä?=?^tBu, R?=?Ph, 2a; C₆H₄-4-Me, 3a; ^tBu, 4a; R¡ä?=?C₆H₄-4-Me, R?=?Ph, 2b) have been synthesised by reaction of [MoBr(R¡ä-dab)(¦Ç-C₇H₇)] with LiCCR in thf. Crystallographic characterisation of [Mo(CCC₆H₄-4-Me)(^tBu-dab)(¦Ç-C₇H₇)], 3a determines a Mo-C_¦Á bond distance of 2.154(3)??. Cyclic voltammetric investigations on the alkynyl complexes 2a, 2b, 3a, 4a and the extended chain butadiynyl derivative [Mo(CCCCSiMe₃)(^tBu-dab)(¦Ç-C₇H₇)], 5a, reveal that each complex exhibits a chemically and electrochemically reversible one-electron oxidation to give the corresponding 17-electron radical cation. Characterisation of the radicals [2a]⁺, [2b]⁺, [3a]⁺, and [5a]⁺ by IR and EPR spectroscopic techniques indicates that the redox process is strongly metal centred. Spectroscopic and synthetic investigations establish that 17-electron radicals of the type [Mo{(CC)_nCCR)}(R¡ä-dab)(¦Ç-C₇H₇)]⁺ (n?=?0 or 1) have relatively low thermodynamic stability.