The standard (pdegrees = 0.1 MPa) molar enthalpies of formation of the crystalline complexes of Ni(II) with three N-benzoylthiocarbamic-O-alkylesters, PhCONHCSOR, R = Et, n-Bu, n-Hex were determined, at T = 298.15 K, by high precision solution and reaction calorimetry. Complex -Delta(f)H(m)degrees(cr)/(kJ (.) mol(-1)) Ni(PhCONCSOEt)(2) 619.2 +/- 6.1 Ni(PhCONCSO-n-Bu)(2) 707.4 +/- 6.2 Ni(PhCONCSO-n-Hex)(2) 802.6 +/- 8.3 From the obtained results, the metal-ligand exchange enthalpies in the crystalline phase were derived, indicating that the increase of the ester-alkyl chain length in these compounds do not significantly affect the difference between the metal-to-ligand-binding enthalpy and the hydrogen-binding enthalpy, {D(M-L) - D(H-L)}. (C) 2004 Elsevier Ltd. All rights reserved.