Solvent-controlled synthesis and reversible dynamic structural conversions of a series of iron(II) coordination complexes.

In this work, a versatile multi-dentate 1,2-bis(pyridin-4-ylmethylene)hydrazine (L) ligand has been employed to construct three novel iron(II) coordination complexes, [Fe(L) 2 (NCS) 2 (H 2 O) 2 ]·2H 2 O ( 1 ), [Fe(L)(NCS) 2 (H 2 O) 2 ] ( 2 ) and {[Fe(L) 2 (NCS) 2 ]·2CH 3 OH} n ( 3 ) (NH 4 NCS = ammonium thiocyanate), which can be isolated under similar synthetic conditions, only different molar ratio of metal/ligand or different solvent systems are used. 1 is a mono-nuclear iron(II) coordination complex, and 2 is a one-dimensional (1D) iron(II) coordination complex, while 3 is a 2D micro-porous iron(II) framework with the channel dimensionality of 13.936(3) Å × 13.936(3) Å. PXRD patterns also confirm the purity of the bulky samples of 1 – 3 . For 1 – 3 , it represents the first example of solvent-induced drastic reversible dynamic conformation between different dimensional iron(II) coordination complexes 1 (0D), 2 (1D) and 3 (2D) (for 1 : water; for 2 : benzene; for 3 : methanol/acetone/acetonitrile), which are unambiguously confirmed by PXRD characterizations. Variable-temperature magnetic susceptibility data of 2 – 3 have been recorded in the 2–300 K temperature range, indicating weak antiferromagnetic interactions. [ABSTRACT FROM AUTHOR]