Two salts containing bis(maleonitriledithiolate)nickel(III)/copper(II) anion and substituted benzyltriphenylphosphinium: Syntheses, crystal structures and magnetic properties

摘要

Syntheses, crystal structures and magnetic properties of two salts, [FBzTPP][Ni(mnt)_2](1) and [FBzTPP]_2[Cu(mnt) _2](2) ([FBzTPP]~+ = 1-(4′-fluorobenzyl) triphenylphosphinium, mnt~(2-) = maleonitriledithiolate), are investigated. In 1, the anions and cations stack into well-segregated columns, and the Ni(III) ions form a 1D alternating chain in a [Ni(mnt)_2] ~- column through intermolecular Ni?S and π?π interactions with the Ni?Ni distances of 3.939, 4.057 and 4.101, and the C-H?N hydrogen bonds are found between the [Ni(mnt)_2] ~- anion and the neighboring [FBzTPP]~+ cation. The [Cu(mnt)_2]~(2-) anions in 2 do not form a column and no weak interactions exist between the anions duo to isolation of the [FBzTPP] ~+ cations, while C-H?F and C-H?S hydrogen bonds were found in 2. Magnetic susceptibility measurements in the temperature range 2-300 K show that 1 exhibits a spin-gap transition around 46 K, and antiferromagnetic interaction (θ = -49.0 K) in the high-temperature phase (HT) and spin gap (Δ/k_b = 88.2 K) in the low-temperature phase (LT), while 2 shows a very weak antiferromagnetic coupling behavior with θ = -1.33 × 10~(-2) K.