The reaction between the magnesium β-diketonate complex Mg(tmhd) 2 (H 2 O) 2 and 1equiv. of N,N,N′,N′-tetramethylethylenediamine (tmeda=Me 2 NCH 2 CH 2 NMe 2 ) in hexane at room temperature yielded Mg(tmhd) 2 (tmeda). The standard enthalpy of sublimation (83.2±2.3kJmol −1 ) and entropy of sublimation (263±6.3Jmol −1 K −1 ) of Mg(tmhd) 2 (tmeda) were obtained from the temperature dependence vapour pressure, determined by adopting a horizontal dual arm single furnace thermogravimetric analyser as a transpiration apparatus. From the observed melting point depression DTA, the standard enthalpy of fusion (58.3±5.2kJmol −1 ) was evaluated, using the ideal eutectic behaviour of Mg(tmhd) 2 (tmeda) as a solvent with bis(2,4-pentanedionato)magnesium(II), Mg(acac) 2 as a non-volatile solute.