Thermochemical studies of five crystalline bis(O-alkyl-N-thenoylthiocarbamato)nickel(II) complexes

The standard (p∘ = 0.1 MPa) molar enthalpies of the crystalline complexes of five N-thenoylthiocarbamic-O-alkylesters, C4H3SCONHCSOR, R = Et, n-Pr, n-Bu, n-Pen, n-Hex, with Ni(II), were determined, at T = 298.15 K, by high precision solution-reaction calorimetry.Nickel(II) complex-ΔfHm∘(cr)/(kJ·mol-1)Bis(O-ethyl-N-thenoylthiocarbamato)nickel(II) Ni(C4H3SCONCSOEt)2629.7 ± 7.0Bis(O-n-propyl-N-thenoylthiocarbamato)nickel(II) Ni(C4H3SCONCSO-n-Pr)2636.8 ± 6.0Bis(O-n-butyl-N-thenoylthiocarbamato)nickel(II) Ni(C4H3SCONCSO-n-Bu)2681.1 ± 6.1Bis(O-n-pentyl-N-thenoylthiocarbamato)nickel(II) Ni(C4H3SCONCSO-n-Pen)2750.2 ± 8.5Bis(O-n-hexyl-N-thenoylthiocarbamato)nickel(II) Ni(C4H3SCONCSO-n-Hex)2804.8 ± 8.6The results are analyzed in terms of structural contribution to the standard molar enthalpies of formation. The metal-ligand exchange enthalpies in the crystalline phase show that the increase of the ester-alkyl chain length does not significantly affect the difference between the metal to ligand and the hydrogen to ligand binding enthalpies, [D(M-L) − D(H-L)].