Kennedy Alan R, MacLellan Jonathan G, Mulvey Robert E
Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow G1 1XL, Scotland.
Acta Crystallogr C. 2003 Aug;59(Pt 8):m302-3. doi: 10.1107/s0108270103011727. Epub 2003 Jul 12.
A 'missing' member of the inverse crown ether family, namely mu(4)-oxo-tetrakis(mu-2,2,6,6-tetramethylpiperidinido)dimagnesium(II)disodium(I), [Na(2)Mg(2)O(C(9)H(18)N)(4)], has been synthesized by blocking the alternative aromatic metallation route via the use of sterically hindered 1,3,5-mesitylene as a solvent. [Na(2)Mg(2)O(NR(2))(4)] (NR(2) is 2,2,6,6-tetramethylpiperidinide) is shown to form a cationic planar eight-membered ring with alternating metal and N atoms, which captures at its core an oxide guest that lies on an inversion centre [principal dimensions: Na-O = 2.2405 (11) A, Na-N = 2.445 (3) and 2.572 (3) A, Mg-O = 1.8673 (9) A, and Mg-N = 2.032 (2) and 2.063 (2) A].
通过使用空间位阻较大的1,3,5-均三甲苯作为溶剂来阻断另一条芳基金属化途径，合成了冠醚反式家族中一个“缺失”的成员，即μ(4)-氧代-四(μ-2,2,6,6-四甲基哌啶基)二镁(II)二钠(I)，[Na₂Mg₂O(C₉H₁₈N)₄]。[Na₂Mg₂O(NR₂)₄]（NR₂为2,2,6,6-四甲基哌啶基）形成了一个阳离子平面八元环，其中金属和氮原子交替排列，其核心捕获了一个位于对称中心的氧化物客体[主要尺寸：Na-O = 2.2405 (11) Å，Na-N = 2.445 (3) 和2.572 (3) Å，Mg-O = 1.8673 (9) Å，以及Mg-N = 2.032 (2) 和2.063 (2) Å]。
