6533b862fe1ef96bd12c7580

RESEARCH PRODUCT

Cation and Anion Coordination Chemistry of Palladium(II) with Polyazacycloalkanes. Thermodynamic and Structural Studies

subject

description

The interaction of PdCI2 4 - with the macrocyclic ligands of the series [3k]aneNk has been studied both in solution and in the solid state. [18]aneN6 and [21]aneN7 form both mono- and binuclear Pd2+ complexes, whose stability constants have been determined in 0.5 mol dm-3 NaCI at 298.15 K. [21]aneN7 also forms, in solution, a trinuclear species in which an amino group deprotonates to bridge two Pd2+ ions, as observed in the solid state. The crystal structure of the complexes [Pd2([18]aneN6)Cl2][CIO4]2 and [Pd3[21]aneN7)CI3][CIO4]2 ⋅ H2O have been solved by single crystal X-ray analysis. C12H30N6CI4O8Pd2: monoclinic, space group C2/m, a = 10.876(2), b = 18.117(2), c = 7.043(2) A, s = 113.78(2)°, V= 1270(12) A3, Z = 2, Dcalc= 1.92gcm-3, μ = 16.94cm-1. R = 0.063, Rw = 0.059. C14H36N7CI5O9Pd3: orthorhombic, space group Pcab, a = 13.125(7), b = 13.213(3), c = 33.570(5) A, V=5822(3)A3, Z=8, Dcalc =2.15gcm-30, μ=21.20cm-1. R=0.074, Rw=0.061. In very acidic solutions the polyammonium cations (Hk[3k]aneNk)k+ interact with PdCI2 4 - forming second sphere coordinated species. These reactions have been followed by a microcalorimetric technique in 2 mol dm-3 HCI solutions. The slowness of the reactions of (H10[30]aneN10)10+ with PdCI2 4 - has been interpreted in terms of inclusion of the anion into the receptor’s cavity as shown by the crystal structure of [(PdCI4)(H10[30]aneN10)][PdCI4]2CI4: triclinic, space group PĪ, a = 7.760(3), b = 11.448(4), c = 13.399(11) A, α = 96.31(8)°, β = 104.50(6)°, γ = 92.30(3)°, Z = 1. R = 0.046 and Rw = 0.039.