Crystal-to-Crystal Transformation from K2[Co(C2O4)2(H2O)2]·4H2O to K2[Co(μ-C2O4)(C2O4)

Bin Zhang,Yan Zhang,Zheming Wang,Daoben Zhu,Guangcai Chang

doi:10.3390/magnetochemistry7060077

Abstract

Crystal-to-crystal transformation is a path to obtain crystals with different crystal structures and physical properties. K2[Co(C2O4)2(H2O)2]·4H2O (1) is obtained from K2C2O4·2H2O, CoCl2·6H2O in H2O with a yield of 60%. It is crystallized in the triclinic with space group P1 and cell parameters: a = 7.684(1) Å, b = 9.011(1) Å, c = 10.874(1) Å, α = 72.151(2)°, β = 70.278(2)°, γ = 80.430(2)°, V = 670.0(1) Å3, Z = 2 at 100 K. 1 is composed of K+, mononuclear anion [Co(C2O4)2(H2O)22−] and H2O. Co2+ is coordinated by two bidentated oxalate anion and two H2O in an octahedron environment. There is a hydrogen bond between mononuclear anion [Co(C2O4)2(H2O)22−] and H2O. K2[Co(μ-C2O4)(C2O4)] (2) is obtained from 1 by dehydration. The cell parameters of 2 are a = 8.460(5) Å, b = 6.906 (4) Å, c = 14.657(8) Å, β = 93.11(1)°, V = 855.0(8) Å3 at 100 K, with space group in P2/c. It is composed of K+ and zigzag [Co(μ-C2O4)(C2O42−]n chain. Co2+ is coordinated by two bisbendentate oxalate and one bidentated oxalate anion in trigonal-prism. 1 is an antiferromagnetic molecular crystal. The antiferromagnetic ordering at 8.2 K is observed in 2.

Highlights

The change of the weak interaction of guest molecules, coordination geometry distortion, and coordination number in coordination compounds can effectively modulate the physical properties as magnetism, absorption, and chirality, so the dynamic molecular crystals have received great attention for their potential applications in molecular devices, as molecular sensors and switches become a powerful method for obtaining a specific compound with the yield of 100% by crystal-to-crystal transformation in crystal engineering [1,2,3,4,5,6,7]
The crystal-to-crystal transformations were observed between different dimensional coordination units as zero-dimensional (0D), one-dimensional chain (1D), two-dimensional (2D) layer, and three-dimensional (3D) coordination frameworks [8,9,10]
We are interested in dynamic crystals of MX2 –(1,4-dioxane)–H2 O system, and 0D to 2D, 1D

Summary

Introduction

The change of the weak interaction of guest molecules, coordination geometry distortion, and coordination number in coordination compounds can effectively modulate the physical properties as magnetism, absorption, and chirality, so the dynamic molecular crystals have received great attention for their potential applications in molecular devices, as molecular sensors and switches become a powerful method for obtaining a specific compound with the yield of 100% by crystal-to-crystal transformation in crystal engineering [1,2,3,4,5,6,7]. The research on oxalate-based dynamic crystal is limited. We present a crystal-to-crystal transformation from 0D mononuclear compound K2 [Co(C2 O4 ) (H2 O)2 ]·4H2 O (1) into a reported. Magnetochemistry 2021, 7, 77 changes in crystal color, cell parameters, space group, coordination environment, crystal structure, and magnetic property

Experiment and Discussion

O: O14-H12

K cm reached

2: On χ versus

Conclusions