Anion coordination directed synthesis patterns for [Ni4] aggregates: structural changes for thiocyanate coordination and ligand arm hydrolysis. (18th September 2018)

• Record Type: Journal Article
• Authors: Das, Manisha; Herchel, Radovan; Trávníček, Zdeněk; Bertolasi, Valerio; Ray, Debashis
• Is Part Of: New journal of chemistry. Volume 42:Number 20(2018)
• Page Start: 16717
• Page End: 16728
• Publication Date: 2018-09-18
• Subjects: Chemistry -- Periodicals; Chimie -- Périodiques; 540
• DOI: 10.1039/c8nj03269f
• Languages: English
• ISSNs: 1144-0546

Abstract

Abstract : Competitive bridging modes of HO − and NCS − were explored for four Ni II -based coordination aggregates in cubane and dicubane topology. Abstract : The coordination reactivity of ligand H5 L1 (2, 6-bis-{(1, 3-dihydroxy-2-methylpropan-2-ylimino)methyl}-4-methylphenol) toward nickel(ii ) ions in the presence of two different anions resulted in cubane and fused dicubane types of tetranuclear coordination aggregates. In the first case, utilization of two carboxylate (R = Me and Et in RCO2 − ) anions led to cubane type Ni4 O4 aggregates [Ni4 (H4 L1)2 (μ3 -OH)2 (μ1, 3 -O2 CCH3 )2 ](NO3 )(CH3 COO)·3H2 O (1 ) and [Ni4 (H4 L1)2 (μ3 -OH)2 (μ1, 3 -O2 CC2 H5 )2 ](NO3 )(C2 H5 COO)·CH3 CN·1.5H2 O (2 ). Whereas the use of thiocyanate anions triggered single imine arm hydrolysis of H5 L1 and gave partial dicubane type Ni4 N2 O4 aggregates [Ni4 (H2 L2)2 (HAMP)2 (μ1, 1 -NCS)2 ](NO3 )2 (3a ) and [Ni4 (H2 L2)2 (HAMP)2 (μ1, 1 -NCS)2 ]Cl2 ·CH3 OH·H2 O (3b ) (H2 L2 = 3-{(1, 3-dihydroxy-2-methylpropan-2-ylimino)methyl}-2-hydroxy-5-methylbenzaldehyde). Liberated 2-amino-2-methyl-1, 3-propanediol from imine arm hydrolysis was successfully trapped in3a and3b for the growth and stabilization of different molecular architectures. Mass spectral evidence established that two types of dinuclear fragments Ni2 (H4 L1) and Ni2 (H2 L2), from the originally used and partially hydrolyzed ligand anions have been self-assembled for two types of Ni II based coordination aggregates. Two sets of complexes were characterized by elemental analysis, FT-IR and optical spectroscopy, variable temperature magnetic measurements, and single crystal X-ray analysis. The magnetic behavior examined through the temperature interval of 1.9–300 K with experimental and theoretical corroboration support the exchange pathways within the two types of [Ni4 ] coordination aggregates.