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)A, b = 16.1798(19)A, c = 14.1544(13)A, β = 90.090(4)°, V = 2134.4(4)A3 for 1; a = 10.5676(3)A, b = 17.1804(5)A, c = 12.0353(4)A, β = 90.7430(10)°, V = 2184.89(11)A3 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 Pt N(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.