I.I. Eliseev, P.V. Gushchin, Yi.-A. Chen, P.-T. Chou, M. Haukka, G.L. Starova, V.Yu. Kukushkin
“Phosphorescent Pt(II) Systems Featuring Both 2,2’-Dipyridylamine and 1,3,5-Triazapentadiene Ligands”
Eur. J. Inorg. Chem. 2014 , 4101-4108
DOI:10.1002/ejic.201402364
The treatment of cis-[Pt(dpa)(RCN)2][SO3CF3]2 {dpa = 2,2′-dipyridylamine, R = Me, Et, CH2Ph, Ph; [2a–d](OTf)2} (OTf = SO3CF3) with 2 equiv. of N,N′-diphenylguanidine [NH=C(NHPh)2] in CH2Cl2 solutions at room temp. for 16 h gives [Pt(dpa){NH=C(R)NC(NHPh)=NPh}][SO3CF3] {[3a,b,d](OTf)} as the addition products and [Pt(dpa){NH=C(R)NHC(R)=NH}][SO3CF3]2 {[4a,b](OTf)2} as the tailoring products. The formulation of complexes [3a,b,d](OTf) and [4a,b](OTf)2 was supported by satisfactory C, H, and N elemental analyses and agreeable high-resolution ESI-MS, IR, and 1H (including 1H–1H COSY experiments) and 13C{1H} NMR data. The structures of all of the platinum species were determined by single-crystal X-ray diffraction. The resultant complexes are nonemissive in solution, mainly because of the interaction between the empty dz2 orbital in a square-planar configuration and solvent molecules. However, in the solid state, complexes [3a,b,d](OTf) exhibit strong phosphorescence with quantum yields (peak wavelength) of 0.23 (490 nm), 0.27 (483 nm), and 0.20 (532 nm), respectively.