Synthesis, structural characterisation and photophysics of anionic cyclometalated bis(alkynyl)(benzo[h]quinolinate)platinate(ii) species
Abstract
The alkynylation of [Pt(bzq)(μ-Cl)]2
(bzqH = CR in
CR)2]−
(R =
tBu 1, SiMe32, Ph 3, Tol 4, C6H4CF3-4 5, C5H4N-2 6, C6H4–C
CPh 7) which have been isolated as tetrabutylammoniun salts. The molecular X-ray structures of 3 and 6 reveal the presence of discrete anions with bond lengths and angles similar to those of related cyclometalated Pt compounds and no evidence of π–π or Pt–Pt stacking interactions. The influence of the R substituent on the photophysics of the complexes has been examined by
CPh)2]−, the emissions are proposed to arise from mixed [π C
CR/Pt d/π
(bzq)
→
π* bzq] transitions. In contrast, complex 7 which contains the extended p-phenylethynylphenylacetylide
CC6H4–C
CPh, displays a structured emission both at 298 K and in glassy CH2Cl2 solutions. In this case the lack of a significant rigidochromism and DFT theoretical calculations support the involvement of a low-lying, metal perturbed acetylenic 3ππ*
(C
CC6H4–C
CPh) excited state.