Thermochemistry On The Complexes Of Hydrated Lanthanide Chloride With Sodium Diethyldithiocarbamate And 1,10-phenanthroline

Thirteen ternary lanthanide complexes have been synthesized with sodium diethyldithiocarbamate(NaEt2dtc), 1,10-phenanthroline (o-phen) and hydrated lanth--anides chloride in absolute ethanol, and their thermochemical characteristics were discussed in this paper.All complexes were identified as the general formula of Ln(Et2Dtc)3(phen)( Ln = La, Pr, Nd, Sm~Lu; Et2Dtc = N, N-diethyldithiocarbamate; phen = 1,10-phenan--throline) by chemical and elemental analyses.IR spectrum of the complexes showed that the Ln3+ is coordinated with six sulfur atoms of three NaEt2dtc and two nitrogen atoms of o-phen. It was assumed that the coordination number of Ln3+ is eight, and the co-ordination geometry approximates to a distorted dodecahedron. As for UV spectrum of the complexes, energy transfer between o-phen and Ln3+ is the primary process. FS spectrum, as a comparison, the complexes Sm (Et2dtc)3(phen) and Eu (Et2dtc)3(phen) have higher efficiency of intramolecular energy transfer and stronger fluorescence characters, which may be used as optical materials.The constant-volume combustion energies, △cU, for the ternary solid complexes were determined by RBCII-type precise rotating-bomb calorimeter at 298.15 K. The standard molar enthalpies of combustion, △cH_m~θ , and standard molar enthalpies offormation, △f H_m~θ , were calculated for these complexes, respectively. The results areas follow:Unit:kJ mol~-1△cU : -17455.98 ±7.98 (La); -17840.67 ± 10.38 (Pr); -18674.22 ± 8.33 (Nd);-17406.90 ± 9.69 (Sm); -17410.63 ± 8.95 (Eu); -18673.71 ± 8.15 (Gd); -17646.95 ± 8.64 (Tb); -16730.21 ± 9.25 (Dy); -18213.19 ±8.18 (Ho); -18436.62 ± 9.11 (Er); -18161.61 ±8.46 (Tm); -17954.08 ± 8.11 (Yb);-17898.22 ± 8.59 (Lu) ACH￡: -17475.19±7.98 (La); -17859.88 ± 10.38 (Pr); -18693.43 ± 8.33 (Nd);-17426.11 ± 9.69 (Sm); -17429.84 ± 8.95 (Eu); -18692.92 ± 8.15 (Gd);-17666.16 ± 8.64 (Tb); -16749.42 ± 9.25 (Dy); -18232.40 ± 8.18 (Ho);-18455.83 ± 9.11 (Er); -18180.82 ± 8.46 (Tm); -17973.29 ± 8.11 (Yb); -17917.43 ± 8.59 (Lu)Aj//^: -1257.78 ±8.84 (La); -888.22 ± 11.55 (Pr); -47.03 ± 9.17 (Nd);-1317.99 ± 10.45 (Sm); -1238.06 ± 9.75 (Eu); -51.28 ± 9.17 (Gd); -1084.04 ± 9.49 (Tb); -2019.68 ±10.19 (Dy); -544.46 ± 9.33 (Ho); -329.48 ± 9.91 (Er); -599.91 ± 9.73 (Tm); -770.36 ± 9.02 (Yb);-859.95 ± 10.12 (Lu)The standard molar enthalpies of combustion and standard molar enthalpies of formation for the complexes were plotted against the atomic numbers of the elements in the lanthanide series, the curves shows the "tripartite effect" of rare earth, On the basis of the curves, the corresponding standard enthalpies of combustion of Ce(Et2dtc)3(phen) and Pm(Et2dtc)3(phen) could be estimated as being -17590 and -18120 kJ-mol"1, the standard enthalpies of formation are as being -1100 and -1650 kJ-mol"1, respectively.The enthalpies of liquid-phase reaction, Ar//^ (L), were determined by a microcalorimeter at 298.15 K, and the enthalpies of the solid-phase reaction, AtH6m (S), were calculated on the basis of a thermochemical cycle. The results are as follow: ArHBm(L)md ATHBm(S), Units: kJ-mol"1-97.858 ± 0.073 and 70.428 ± 0.348 (La); -18.042 ± 0.072 and 137.565 ± 0.320 (Pr); -2.036 ± 0.043 and 149.069 ± 0.314 (Nd); -20.706 ± 0.079 and 138.102 ± 0.483 (Sm); -13.481 ± 0.031 and 152.317 ± 0.542 (Eu); -27.121 ± 0.064 andl29.813 ± 0.519 (Gd); -21.819 ± 0.055 andl28.476 ± 0.675 (Tb); -14.716 ± 0.060 and 144.016 ± 0.264 (Dy); -20.695 ± 0.207 and 117.504 ± 0.619 (Ho); -18.363 ± 0.173 and 115.156 ± 0.695 (Er); -17.847 ± 0.103 and 112.109 ± 0.613 (Tm); -24.838 ±0.114 and 08.015 ± 0.479 (Yb);-32.821 ± 0.147 and 104.160 ± 0.168 (Lu)The values of Ari7? (L) |P ArH^ (S) for the complexes were plotted against theatomic numbers of the elements in the lanthanide series, the curves also presents the "tripartite effect" of rare earth ions.