[Ru(bpy) 2 (bqdiBr 2 )](PF 6 ) 2 bearing a 3,6-dibromo-1,2-benzoquinone diimine ligand (bqdiBr 2 = Br-C 6 H 2 (NH) 2 -Br): Synthesis and its cross coupling reactions with organostannanes and organoboronic acids

[Ru(bpy) 2 (bqdiBr 2 )](PF 6 ) 2 ([ 1 ](PF 6 ) 2 , bpy = 2,2′-bipyridyl, bqdiBr 2 = 3,6-dibromo-1,2-benzoquinone diimine) was synthesized by the reaction of 3,6-dibromo-1,2-phenylenediamine with [RuCl 2 (bpy) 2 ] in air, and the reactivity of [ 1 ](PF 6 ) 2 in Pd-catalyzed cross-coupling reactions with metalated thiophene and benzene was investigated. The structure of [ 1 ](PF 6 ) 2 was determined using X-ray crystallography. The Migita–Kosugi–Stille cross-coupling of [ 1 ](PF 6 ) 2 with 2 equiv of Th-SnBu 3 (Th = 2-thienyl; Bu = butyl) afforded a 3,6-di(2-thienyl)-1,2-benzoquinone diimine (Th-C 6 H 2 (NH) 2 -Th)-coordinated Ru(II) complex [ 2 ](PF 6 ) 2 . Similarly, the Suzuki–Miyaura cross-coupling of [ 1 ](PF 6 ) 2 with 2 equiv of CH 3 OC 6 H 4 -B(OH) 2 - p proceeded smoothly to afford a p -CH 3 OC 6 H 4 -C 6 H 2 (NH) 2 -C 6 H 4 OCH 3 - p -coodinated Ru(II) complex, [ 3 ](PF 6 ) 2 . The optical and electrochemical properties of these complexes were evaluated based on the presence of the extended π-conjugated diimine ligand in the diimine moiety. The Stille cross-coupling of [ 1 ](PF 6 ) 2 with 1 equiv of Me 3 Sn-C 4 H 2 S-SnMe 3 (C 4 H 2 S: thiophene-2,5-diyl) afforded a π-conjugated polymer consisting of the [Ru(bpy) 2 (bqdi)] 2+ units.