Old dog, new tricks: 2,2′-biphenol as a bridging and book-end ligand in discrete and extended Co(ii) architectures

Abstract

We report the first Co(II) based discrete and extended network materials comprising the 2,2′-biphenol ligand. We first present the synthesis and magnetic characterisation of the Co(II) dinuclear complexes [Co(II)₂(L)₂(py)₄]·2EtOH (1) and [Co(II)₂(L)₂(4-pic)₄].2LH₂ (2), both of which exhibit antiferromagnetic exchange between their Co(II) centres. The introduction of the co-ligand 2-hydroxypyridine (2-hpH) leads to the production of planar octametallic complex [Co(II)₈(OMe)₂(L)₄(LH)₂(2-hp)₄(MeCN)₄]·MeCN (3). Magnetic susceptibility and magnetisation measurements on 3 indicate dominant ferromagnetic exchange between the Co(II) centres. We also describe the first Co(II)/2,2′-biphenol extended networks in the shape of the 1D coordination polymer {[Co(II)(LH)(4,4-tmdp)₂(NO₃)](LH₂)}_n (4) (where 4,4′-tmdp = 4,4′-trimethylenedipyridine) and the 2D brickwall network [Co(II)(LH)(trans-bpe)_1.5(NO₃)] (5) (where trans-bpe = trans-1,2-bis(4-pyridyl)ethylene), comprising T-shaped nodes.