Hydrothermal synthesis and thermochemistry of metalloborophosphate of Na2[CuB3P2O11(OH)]·0.67H2O

The pure hydrated metalloborophosphate sample, Na2[CuB3P2O11(OH)]·0.67H2O, has been synthesized and characterized by XRD, FT-IR, DTA-TG techniques, and chemical analysis. The molar enthalpies of solution of Na2[CuB3P2O11(OH)]·0.67H2O(s) in 1 mol · dm−3 HCl (aq), of Cu(OH)2 (s) in (HCl + H3BO3) (aq), and of NaH2PO4·2H2O (s) in (HCl + H3BO3 + Cu(OH)2) (aq) were measured, respectively. With the incorporation of the previously determined enthalpy of solution of H3BO3 (s) in 1 mol · dm−3 HCl (aq), together with the use of the standard molar enthalpies of formation for NaH2PO4·2H2O (s), Cu(OH)2 (s), H3BO3 (s), and H2O (l), the standard molar enthalpy of formation of −(4988.4 ± 2.5) kJ · mol−1 for Na2[CuB3P2O11(OH)]·0.67H2O at T = 298.15 K was obtained on the basis of the appropriate thermochemical cycle.

Research highlights▶ Na2[CuB3P2O11(OH)]·0.67H2O sample has been synthesized and characterized. ▶ The enthalpy of solution of title compound were measured. ▶ The enthalpies of solution of Cu(OH)2(s) and NaH2PO4·2H2O (s) were measured. ▶ ΔfHmo of –(4988.4 ± 2.5) kJ mol–1 for title compound was obtained.