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

Abstract

The standard ( p ∘ = 0.1 MPa) molar enthalpies of the crystalline complexes of five N-thenoylthiocarbamic- O-alkylesters, C 4H 3SCONHCSOR, 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 - Δ f H m ∘ ( cr ) / ( kJ · mol - 1 ) Bis( O-ethyl- N-thenoylthiocarbamato)nickel(II) Ni(C 4H 3SCONCSOEt) 2 629.7 ± 7.0 Bis( O- n-propyl- N-thenoylthiocarbamato)nickel(II) Ni(C 4H 3SCONCSO- n-Pr) 2 636.8 ± 6.0 Bis( O- n-butyl- N-thenoylthiocarbamato)nickel(II) Ni(C 4H 3SCONCSO- n-Bu) 2 681.1 ± 6.1 Bis( O- n-pentyl- N-thenoylthiocarbamato)nickel(II) Ni(C 4H 3SCONCSO- n-Pen) 2 750.2 ± 8.5 Bis( O- n-hexyl- N-thenoylthiocarbamato)nickel(II) Ni(C 4H 3SCONCSO- n-Hex) 2 804.8 ± 8.6 The 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)].