Efficient solid-state microwave-promoted complexation of a mixed dioxa-diaza macrocycle with an alkali salt. Synthesis of a sodium ethyl 4-benzeneazophosphonate complex

The first example of microwave-promoted solid-state synthesis of an alkali complex derived from a heteromacrocyclic compound has been described. The 15-membered mixed dioxa-diaza macrocycle 5,6,14,15-dibenzo-1,4-dioxa-8,12-diazacyclopentadeca-5,14-diene (L) by reaction with sodium ethyl [4-α-(benzeneazoanilino)-N-benzyl]phosphonate (NaEP · 1.5H2O) yielded the sodium complex [Na(L)(μ-EP) · H2O]2, as a diphosphonate-bridged dinuclear species. The new complex was identified and characterized on the basis of elemental and thermal (TG and DTA) analyses as well as by IR, 1H and 13C nuclear magnetic resonance, and ESI and LDI mass spectroscopic studies. The results obtained by the reaction carried out under focused microwave conditions are compared with those obtained by conventional thermal reactions, both in the solid-state and in solution.

Graphical abstractThe simple work-up, eco-friendly microwave-promoted solid-state synthesis of an alkali complex derived from a mixed 15-membered dioxa-diaza macrocycle (L) and sodium monoethyl [4-α-(benzeneazoanilino)-N-benzyl]phosphonate (NaEP) has been described and compared with the syntheses carried out under conventional heating in the solid state and solution. The prepared diphosphonate bridged dinuclear complex, [Na(L)(μ-EP) · H2O]2, has been studied by IR, 1H and 13C NMR, and MS spectroscopy.Figure optionsDownload full-size imageDownload as PowerPoint slide