First examples of metal cyclohexylphosphonates: Influence of the choice of cynthetic route on the product

Abstract

The first divalent metal cyclohexylphosphonate derivative, [Co(O₃PCy).H₂O]_n (1) has been synthesized using four different synthetic methodologies in the presence of added amines. The new phosphonates have been characterized with the aid of analytical, thermoanalytical, spectroscopic, and powder XRD studies. The nature and particle size of the product formed is highly dependent on the method employed (viz. (a) room temperature synthesis, (b) hydrothermal synthesis, (c) microwave assisted synthesis, and (d) a biphasic reaction) as revealed by SEM and TEM studies. While in most cases the metal phosphonates were isolated as insoluble crystalline powders directly from the reaction mixture, the use of 3,5-dimethylpyrazole (DMP) as co-ligand leads to the isolation of soluble compound [{Co(H₂O)₄(DMP)₂}{CyPO₃H}₂]_n (2) as single crystals. The X-ray diffraction studies on 2 reveal a hydrogen-bonded polymeric structure for this compound. Crystal data: C₂₂H₄₈CoN₄O₁₀P₂, monoclinic, P2₁/c, a = 12.147(2), b = 11.607(2), c = 11.872(2) Å , β = 104.00(3)°, V = 1624.2(5) Å3, Z = 2, R1(all data) = 0.050, wR2 (all data) = 0.145.