Luminescent Heterotrinuclear Complexes with Pt(diimine)(dithiolate) and Metal Diphosphine as Components

Reactions of Pt(diimine)(tdt) (tdt =3,4-toluenedithiolate) with [M2(dppm)2(MeCN)2]2+ (M = CuI or AgI, dppm =
bis(diphenylphosphino)methane) gave heterotrinuclear complexes [PtCu2(tdt)(μ-SH)(dppm)3](ClO4) (1) and [PtCu2(diimine)2(tdt)(dppm)2](ClO4)2 (diimine = 2,2‘-bpyridine (bpy) 2; 4,4‘-dimethyl-2,2‘-bipyridine (dmbpy) 3; phenanthroline
(phen) 4, 5-bromophenanthroline (Brphen) 5) for M = CuI, but [PtAg2(tdt)(μ-SH)(dppm)3](SbF6) (6) and [PtAg2(diimine)(tdt)(dppm)2](SbF6)2 (diimine = bpy 7; dmbpy 8; phen 9; Brphen 10) for M = AgI. While the complexes
[PtAg2(diimine)(tdt)(dppm)2](SbF6)2 (7−10) result from linkage of Pt(diimine)(tdt) and [M2(dppm)2(MeCN)2]2+ by tdt
sulfur donors, formation of [PtCu2(diimine)2(tdt)(dppm)2](ClO4)2 (2−5) is related to rupture of metal−ligand bonds in
the metal components and recombination between the ligands and the metal atoms by self-assembly. The formation
of 1 and 6 is involved not only in dissociation and recombination of the metal components, but also in disruption
of C−S bonds in the dithiolate (tdt). The dithiolate tdt adopts a chelating and bridging coordination mode in anti
conformation for [PtCu2(diimine)2(tdt)(dppm)2](ClO4)2 (2−5), whereas there is the syn conformation for other complexes.
Compounds 1 and 6 represent sparse examples of μ-SH-bridged heterotrinuclear PtIIMI2 complexes, in which PtII−MI centers are bridged by dppm and sulfur donors of tdt, whereas MI−MI (M = Cu for 1; Ag for 6) centers are
linked by dppm and the μ-SH donor. The 31P NMR spectra show typical platinum satellites (JPt-P = 1450−1570
Hz) for 1−6 and Ag−P coupling for PtII−AgI (JAg-P = 350−450 Hz) complexes 6−10. All of the complexes show
intense emission in the solid state and in frozen glasses at 77 K. The complexes [PtAg2(diimine)(tdt)(dppm)2](SbF6)2 (7−10) also afford emission in fluid acetonitrile solutions at room temperature. Solid-state emission lifetimes
at room temperature are in the microsecond range. It is revealed that emission energies of the trinuclear heterometallic
complexes [PtAg2(diimine)(tdt)(dppm)2](SbF6)2 (7−10) exhibit a remarkable blue shift (0.10−0.35 eV) relative to
those of the precursor compounds Pt(diimine)(tdt). The crystal structures of 1, 2, 4, 6, 8, and 9 were determined
by X-ray crystallography.