Fine-tuning the effects of auxiliary ligands on two trigonal-bipyramid cobalt(ii) complexes exhibiting field-induced slow magnetic relaxation. (23rd April 2018)

• Record Type: Journal Article
• Authors: Hou, Xiangyang; Wang, Xiao; Liu, Xiangyu; Wang, Jijiang; Tang, Long; Ju, Ping
• Is Part Of: New journal of chemistry. Volume 42:Number 11(2018)
• Page Start: 8583
• Page End: 8590
• Publication Date: 2018-04-23
• Subjects: Chemistry -- Periodicals; Chimie -- Périodiques; 540
• DOI: 10.1039/c8nj01201f
• Languages: English
• ISSNs: 1144-0546

Abstract

Abstract : Two trigonal-bipyramid cobalt(ii ) complexes exhibit field-induced slow magnetic relaxation effects due to their auxiliary ligands. Abstract : Two penta-coordinate Co 2+ complexes, namely [Co(PDA)(H2 O)2 ] (1 ) and [Co(PDA)(1, 2-BIYB)0.5 (H2 O)]·(H2 O) (2 ), (H2 PDA = pyridine-3, 5-dicarboxylate, 1, 2-BIYB = 1, 2-bis(imidazol-1-ylmethyl) benzene), which have similar ligand fields except for their local symmetries due to the different coordination atoms of Co 2+, were synthesized, structurally analyzed, and magnetically investigated. Complexes1 and2 possess 3D supramolecular structures in which the 2D structures are further cross-linked by hydrogen bonds. Complex1 can be observed to transform into2 in the presence of 1, 2-BIYB coligand, and1 and2 have distortion trigonal bipyramid geometries when the space group of Co 2+ ion changes from C 2/ c in1 to P 2(1)/ c in2 . Meanwhile, the average equatorial Co–O/N bond distances of CP1 (2.1655 Å) are clearly larger than its axial Co–O bond distances (2.0704 Å); for CP2, the average equatorial Co–O/N bond distances (2.0814 Å) are slightly shorter than the axial Co–O/N bond distances (2.0896 Å), which leads to different axial compression and distortion of the trigonal bipyramid metal environment. Fine-tuning of the structures arising from the auxiliary ligands has a definite impact on the magnetic properties of compounds1 and2 . Both compounds share easy-plane magnetic anisotropies of their central Co 2+ ions ( D = 16 cm −1 for1 and D = 59 cm −1 for2 ) and different slow magnetic relaxations of magnetization with applied magnetic fields of 1500 Oe and 3000 Oe, respectively.