Phosphorescent Mono and Binuclear 2-Phenylbenzothiazole Platinum Complexes with Pyrazole or Pyrazolate Ligands

Resumen

The use of bidentate cyclometalated C^N ligands allows emission tunability of Pt complexes byvarying the cyclometalated ligand or the nature of the ancillary groups1. By other hand, pyrazole(RpzH)-based complexes are useful in molecular architecture and luminescence. In this sense, bydeprotonation of mononuclear pyrazole Pt complexes, a great variety of luminescent homo andheteropolynuclear pyrazolate complexes [Pt2M2] (M = Ag, Cu)2 and pyrazolate-briged dinuclear PtIIcomplexes have been described3. In this latter, the strength of the metallophilic interactions, whichdepends on the steric hindrance of the pyrazolate substituents, decisively affects to the emissiveproperties. Finally, oxidation processes of pyrazolate-bridged Pt2(II,II) to Pt2(III,III)X2 orPt2(III,III)RX complexes have been recently reported3.In this context, we decided to combine 2-phenylbenzopthiazole (pbt) as cyclometalated ligand andselected RpzH ligands to prepare new stable and efficient photoluminescent Pt compounds. Wepresent here a series of mononuclear bis-pyrazole complexes [Pt(pbt)(RpzH)2]PF6 (RpzH = pz 1,3,5-Me2pzH 2, 3,5-iPr2pzH 3) and their deprotonation to form butterfly-like bis-pyrazolate bridgeddiplatinum complexes {[Pt(pbt)(-Rpz)]2} (4-6). Finally, oxidation of {[Pt(pbt)(-pz)]2} 4 affordedthe symmetrical Pt2(III,III)Cl2 {[Pt(pbt)(-pz)Cl]2} 7. Here we describe their synthesis andcharacterization and a comparative study of the optical properties of mononuclear and binuclear PtIIcomplexes. The Pt2(III,III)Cl2 complex 7 shows an exceptional emission in rigid media