A Unique Example of Structural Diversity Tuned by Apparently Innocent o-, m-, and p-Nitro Substituents of Benzoate in Their Complexes of Mn(II) with 4,4鈥?Bipyridine: 1D Ladder, 2D
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- 作者：Paramita Kar ; Rituparna Biswas ; Yumi Ida ; Takayuki Ishida ; Ashutosh Ghosh
- 刊名：Crystal Growth & Design
- 出版年：2011
- 出版时间：December 7, 2011
- 年：2011
- 卷：11
- 期：12
- 页码：5305-5315
- 全文大小：1177K
- 年卷期：v.11,no.12(December 7, 2011)
- ISSN：1528-7505
文摘
Four new Mn(II) coordination polymers [Mn(4,4鈥?bpy)(C6H5COO)2]n (1), [Mn(4,4鈥?bpy)(o-(NO2)C6H4COO)2]n (2), [Mn(4,4鈥?bpy)(m-(NO2)C6H4COO)2]n (3), and [Mn(4,4鈥?bpy)(p-(NO2)C6H4COO)2]n (4) (where 4,4鈥?bpy = 4,4鈥?bipyridine) have been synthesized by self-assembly of the primary ligands, benzoate and the o-, m-, and p-isomers of nitrobenzoates, respectively, together with 4,4鈥?bpy as the secondary spacer. All four complexes were characterized by elemental analyses, IR spectroscopy, single-crystal X-ray diffraction analyses, and variable-temperature magnetic measurements. The structural analyses reveal that complexes 1 and 3 are constructed by linear fused chains through double syn-syn (for 1) or syn-anti (for 3) carboxylate-bridged Mn(II), which are further linked to one another by trans coordinated 4,4鈥?bpy bridges, giving rise to a rectangular grid-like two-dimensional (2D) net. Complex 2 features one-dimensional (1D) molecular ladder formed by both syn-syn and syn-anti carboxylate-bridged dimeric Mn(II) units which are joined alternately by 4,4鈥?bpy. Complex 4 is formed by fused zigzag chains of double syn-syn carboxylate-bridged Mn(II) that are connected by cis oriented 4,4鈥?bpy to generate an unprecedented three-dimensional (3D) framework. The dimensionality of the complexes thus varies from 1D to 2D to 3D on changing the position of the nitro group from o- to m- to p- in the benzoate, showing explicitly the tuning ability of this apparently innocent substituent on the topology of the coordination polymer. Variable-temperature (1.8鈥?00 K) magnetic susceptibility measurements showed the presence of antiferromagnetic coupling in all four complexes that have been fitted with an infinite classical-spin chain model derived by Fisher for 1, 3, and 4 (J = 鈭?.779(2), 鈭?.855(2), and 鈭?.536(2) cm鈥?, respectively) and van Vleck equation for 2 (J = 鈭?.354(2) cm鈥?).