| Abstract
| - Three new platinum complexes containing 3,3‘-biisoquinoline(i-biq), [Pt(CN)2(i-biq)](1), [PtCl2(i-biq)](2), and[Pt(i-biq)2](PF6)2(3), have been synthesized as orange-red, yellow, andcolorless crystals, respectively. Theircrystal structures and luminescence properties are reported.Crystal data: for 1·0.5H2O,PtO0.5N4C20H13,orthorhombic, Pbcm, a = 13.989(2) Å,b = 18.304(1) Å, c = 6.682(3) Å,V = 1710.9(6) Å3, Z = 4,and final R= 0.039 (Rw = 0.033) for 970 independentreflections; for 2·DMF·H2O,PtCl2O2N3C21H21,triclinic, P1̄, a =11.047(1) Å, b = 12.397(3) Å, c =8.000(2) Å, α = 106.56(1)°, β = 100.15(1)°,γ = 76.15(1)°, V = 1012.8(3)Å3, Z = 2, and final R = 0.058(Rw = 0.077) for 4219 independent reflections;for 3·2DMF,PtP2F12O2N6C42H38,triclinic, P1̄, a = 10.795(2) Å,b = 13.511(2) Å, c = 8.281(1) Å,α = 105.22(1)°, β = 112.17(1)°, γ =85.02(1)°,V = 1079.2(3) Å3, Z = 1,and final R = 0.038 (Rw = 0.042)for 3606 independent reflections. Square-planarcomplexes of 1 are stacked in the crystal to form a columnarstructure with the Pt−Pt distance of 3.34 Å. Thecrystal emits strongly, even at room temperature, and the emissionspectrum is similar to that for the[Pt(CN)2(bpy)] crystal (bpy = 2,2‘-bipyridine), which is due to a3dπ*[dσ*(Pt) →π*(i-biq)] transition. The singlecrystalemission spectrum at 77 K is, however, observed as a superposition ofbroad 3dπ* and sharp3ππ*(i-biq) emissions.The crystal structure of 2 has a completely differentstacking structure from that of 1. The stacking occurson thei-biq ligands, and the Pt atoms are separated more than 6Å. The complex exhibits only a structured emissioncomponent assigned to the 3ππ*(i-biq)transition in the crystal at 77 K, in agreement with the crystalstructurewith no Pt−Pt interaction. In the crystal of 3, the[Pt(i-biq)2]2+ complexesare stacked but offset, being in closecontact between parts of adjacent i-biq ligands. Thereis no Pt−Pt interaction also in this case. Two i-biqligandsin the complex are distorted to adopt the bowed conformation due to thesteric crowding of the α-hydrogens onopposite ligands. Nevertheless, 3 provides almost thesame 3ππ* emission spectrum as 1 and2 in dilute glassysolution at 77 K. The 3ππ* emission spectraobserved in the crystals of these Pt(II) complexes arered-shiftedcompared with those in dilute glassy solution. The fact isattributable to the π−π intermolecular interactionsbetween the ligands in the crystals. The factors controlling thecrystal structures for these complexes are alsodiscussed.
- Three new platinumcomplexes containing a large π-system ligand 3,3‘-biisoquinoline(i-biq),[Pt(CN)2(i-biq)],[PtCl2(i-biq)], and[Pt(i-biq)2](PF6)2,have been synthesized and structurally characterized. Thesignificant differences in the stacking structures among them areascribed to various intermolecular interactions such as metal−metalinteractions and ligand π−π interactions. In connection withthe crystal structure, the characteristic luminescence behavior hasbeen observed.
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