The volatile trimethylplatinum(IV) complexes: Effect of β-diketonate substituents on thermal properties

Abstract

The series of trimethylplatinum(IV) complexes with a general formula (CH3)3Pt(L)Py: [L− = β-diketonate ligand: (1) tBuC(O)CHC(O)C(OCH3)(CH3)2) – L1, (2) CF3C(O)CHC(O)CC(CH3)2 (OCH3)) – L2, (3) CF3C(O)CHC(O)C4H3S – ttfa, (4) CF3C(O)CHC(O)tBu – ptac, Py –pyridine] were synthesized with high yields using novel synthesis technique based on the interaction of (CH3)3PtI with an appropriate PbL2. A number of methods including elemental analysis, IR and NMR spectroscopy, were used to identify the purity of complexes. Both 1 and 3 crystals are monoclinic, P21/n, Z = 4. The crystallographic parameters are: a = 9.3199(11)Å, b = 16.1798(19)Å, c = 14.1544(13)Å, β = 90.090(4)°, V = 2134.4(4)Å3 for 1; a = 10.5676(3)Å, b = 17.1804(5)Å, c = 12.0353(4)Å, β = 90.7430(10)°, V = 2184.89(11)Å3 for 3, respectively. The temperature dependences of saturated vapor pressure of the complexes were measured using Knudsen method giving logP = 17.3–6908/T, ΔT = 326–353 K and logP = 17.7–6793/T, ΔT = 303–333 K, for 1 and 4, respectively. The effect of substituents combination in L on thermal stability of (CH3)3Pt(L)Py vapors was studied using mass spectrometry. The energies of PtN(Py) bonds of (CH3)3Pt(L)Py calculated using DFT approach were in the ranges of 78.97–92.73 and 73.32–83.09 kJ/mol depending on Py rings orientation.