Syntheses, molecular and supramolecular structures, and magnetic properties of a mononuclear MnII and a dicyanamide-bridged one-dimensional CuII compound derived from enolic 4-terpyridone

Syntheses, molecular and supramolecular structures, and magnetic properties of a mononuclear manganese(II) compound [MnII(LH)2](ClO4)2 (1) and a dicyanamide-bridged one-dimensional copper(II) compound [CuII(LH)(μ1,5-dca)]n(NO3)n (2) derived from enolic 4-terpyridone (LH) have been described. The compounds 1 and 2 crystallize in monoclinic P2(1)/nP2(1)/n and triclinic P1¯ space groups, respectively, with the following unit cell parameters – 1: a = 8.8281(4) Å, b = 8.7736(4) Å, c = 39.7838(16) Å, β = 95.719(1)°, and Z = 4; 2: a = 7.5342(3) Å, b = 8.9307(4) Å, c = 15.0189(8) Å, α = 73.0032(15)°, β = 81.3701(16)°, γ = 65.461(2)°, and Z = 2. In 1, the metal center is hexacoordinated by three pyridine nitrogens of each of the two enolic 4-terpyridones. In 2, the metal center is pentacoordinated by three pyridine nitrogens of 4-terpyridone and two nitrogens of two end-to-end (EE; μ1,5-) dicyanamide. The coordination geometries of 1 and 2 are distorted octahedral and distorted square pyramidal, respectively. Eight hydrogen bonds, six of C–H⋯O types and two of O–H⋯O types, link the complex cation [MnII(LH)2]2+ and two perchlorate anions into a three-dimensional network in 1. In the case of 2, seven hydrogen bonds, six of C–H⋯O types and one of O–H⋯O type, link the dicyanamide-bridged one-dimensional chains into a two-dimensional sheet consisting of interlinked one-dimensional double-chains. It may be noted that O–H group of enolic 4-terpyridone participates in hydrogen bonding interactions and in developing extended structures in both 1 and 2. Variable-temperature (2–300 K) magnetic susceptibility measurements of both the compounds have been performed to understand the possibility of spin transition in 1 and exchange interaction in 2. However, the susceptibility data of 1 indicate the existence of high-spin manganese(II) throughout the temperature range. In the case of 2, copper(II) centers are noninteracting which is related to the highly distorted coordination geometry of the metal ion.

Syntheses, molecular and supramolecular structures, and magnetic properties of a mononuclear manganese(II) compound [MnII(LH)2](ClO4)2 and a dicyanamide-bridged one-dimensional copper(II) compound [CuII(LH)(μ1,5-dca)]n(NO3)n derived from enolic 4-terpyridone (LH) have been described.Figure optionsDownload as PowerPoint slide