198623-77-7Relevant academic research and scientific papers
Electronic and molecular structure of 2,2′-bipyrimidine-bridged bis(organoplatinum) complexes in various oxidation states. Radical-bridged diplatinum species and the absence of a Pt(III)/Pt(II) mixed-valent intermediate
Klein, Axel,Kaim, Wolfgang,Hornung, Fridmann M.,Fiedler, Jan,Zalis, Stanislav
, p. 269 - 278 (2008/10/08)
Dinuclear organoplatinum compounds RnPt(bpym)PtRn (R = Me = methyl, n = 2, 4; R = Mes = mesityl, n = 2; bpym = 2,2′-bipyrimidine) were prepared and characterized. The neutral compounds and their neighboring oxidation states were studied using cyclic voltammetry, 1H NMR or EPR spectroscopy and UV-Vis spectroelectrochemistry. Oxidation state assignments based on these data could be made for the following compounds: R2PtII(bpym)PtIIR2, [R2PtII(bpym-I)PtIIR2] ?-, [R2PtII(bpym-II)PtIIR 2]2-, [Mes2PtIII(bpym)PtIIIMes2] 2+, Me4PtIV(bpym)PtIVMe4, [Me4PtIV(bpym-I)PtIVMe 4]?-. The two-electron oxidation of MeS2Pt(bpym)PtMes2, i.e. the absence of a stable Pt(III)/Pt(II) mixed-valent state, confirms that the highest-lying occupied metal orbitals (dz2) do not communicate via the π system of the bridging ligand. A crystal structure analysis of photoreactive Me4PtIV(bpym)PtIVMe4 was obtained: space group Pbca, a := 12.830(2) A?, b = 11.502(2) A?, c = 12.877(2) A?, V = 1900.3(5) A?3, Z=4. The structural refinement revealed elongated axial Pt-methyl bonds of about 2.13 A?. The structural features could be well reproduced by a DFT calculation of H4PtIV(bpym)PtIVH4 which also confirmed the σ character of the HOMO. Of the ligand-reduced systems, the Pt(II) species exhibits a higher degree of g anisotropy than the Pt(IV) species. Low-lying excited states of the species generated were assigned through information from vibrational structuring, solvatochromic behavior and from (spectro)electrochemical results.
