Linking Tribridged Dicopper Complexes with Neutral Dipyridyl Compounds to Coordination Oligomers and Polymers

Abstract

The stable tribridged dicopper(I) carboxylate complexes [Cu2(μ‐dppm)2(μ‐O2CR)]BF4 (RCO2 − = formate (OFc−), m1; acetate (OAc−), m2; benzoate (OBAc−), m3; o‐toluate (O2TAc−), m4; p‐toluate (O4TAc−), m5; 4‐phenylbutyrate (O4PBAc−), m6; 2‐nitrobenzoate (O2NBAc−), m7), abbreviated as MM, and neutral dipyridyl compounds (NN; NN = 4,4′‐bipyridine (bpy), 1,2‐bis(4‐pyridyl)ethane (bpa), trans‐1,2‐bis(4‐pyridyl)ethylene (bpe), 4,4′‐trimethylenedipyridine (tmp)) can form dynamic equilibria in CH2Cl2. From the equilibrium mixtures containing MM and NN with MM/NN = 1:1, nine 2:1 oligomers ([(m1)2(μ‐bpy)](BF4)2 (o1a(BF4)2), [(m3)2(μ‐bpe)](BF4)2 (o3c(BF4)2), [(m3)2(μ‐tmp)](BF4)2 (o3d(BF4)2), [(m4)2(μ‐bpe)](BF4)2 (o4c(BF4)2), [(m5)2(μ‐bpy)](BF4)2 (o5a(BF4)2), [(m5)2(μ‐tmp)](BF4)2 (o5d(BF4)2), [(m6)2(μ‐bpa)](BF4)2 (o6b(BF4)2), [(m7)2(μ‐bpy)](BF4)2 (o7a(BF4)2), [(m7)2(μ‐bpa)](BF4)2 (o7b(BF4)2)), one 2:3 oligomer ([{(m2)(bpy)}2(μ‐bpy)](BF4)2 (o2a(BF4)2)), and five 1:1 polymers ([(m2)(μ‐bpe)] n (BF4 ) n (p2c(BF4 ) n ), [(m2)(μ‐tmp)] n (BF4 ) n (p2d(BF4 ) n ), [(m3)(μ‐bpy)] n (BF4 ) n (p3a(BF4 ) n ), [(m3)(μ‐tmp)] n (BF4 ) n (p3d(BF4 ) n ), [(m7)(μ‐tmp)] n (BF4 ) n (p7d(BF4 ) n )) were obtained as single crystals, and their structures were determined by X‐ray crystallography. Both experimental and theoretical results support the presence of two oligomeric species, [{Cu2(μ‐dppm)2(μ‐O2CR)}2(μ‐NN)]2+ and [{Cu2(μ‐dppm)2(μ‐O2CR)(NN)}2(μ‐NN)]2+), in dynamic equilibrium. The oligomers (such as o3d(BF4)2) can serve as seeds to induce the formation of soluble coordination polymers as crystals (such as p3d(BF4)n).