DPP dyes as ligands in transition-metal complexes.
The DPP dyes (=diketopyrrolopyrrole) 1 are deprotonated to give the corresponding dianions 2. These are treated with two moles of the transition-metal complexes [L(n)MX]=[(Ph(3)P)(2)MX] (M=Cu, Ag; X=Cl, NO(3)), [(Ph(3)P)AuCl], [(Et(3)P)AuCl], [(tBuNC)AuCl], [(Ph(3)P)(2)PdCl(2)], and [(Ph(3)P)(2)PtCl(2)] to give the novel bismetalated DPP dyes [L(n)MN[C(3)R(1)(O)](2)NML(n)] (4-10). In comparison with the starting materials, these compounds show better solubilities, high fluorescence quantum yields (Phi > or = 80 %), and bathochromic absorptions. The compounds 4 c, 5 a, 6 b, 6 c, 6 e, 7 c, and 8 c were characterized by X-ray crystallography. The copper and silver atoms in 4 c and 5 a are trigonal planar and are surrounded by the P atoms of the phosphane ligands and the N atom of the DPP dianion 2. Both metals are somewhat forced out-of-plane, and the P(2)M plane and the phenyl planes of R1 are twisted by > or = 70 degrees and < or = 25 degrees, respectively, towards the chromophore plane. The gold atoms in 6-8 are linearly coordinated to one N and one P (6 b, c, e, 7 c) or one C atom (8 c), respectively. The gold atoms are only slightly pressed out-of-plane, and the P substituents are staggered so that there is enough space for the planarization of R(1) into the plane of the chromophore. Compound 8 c shows intermolecular d(10)-d(10) interactions between Au(I) centers of different molecules, and these interactions lead to infinite chains of parallel orientated molecules in a gauche conformation of neighbors (torsion angle=150 degrees) in the crystal.