Structurally diverse dinuclear Cu(I) complexes and 1D helical Cu(I) coordination polymers bridged by 2,2′:6′,4″-terpyridine

The reactions of [Cu(MeCN)4]PF6 or [Cu(C2H4)n]ClO4 with 2,2′:6′,4″-terpyridine (2,2′:6′,4″-terpy) in MeOH under C2H4 afforded dinuclear Cu(I) complexes [Cu2(2,2′:6′,4″-terpy)2](PF6)2 (1) and [Cu2(2,2′:6′,4″-terpy)2(ClO4)2] (2), respectively. In complex 1, the Cu(I) atom is coordinated by one N atom in the terminal site of 2,2′:6′,4″-terpy and two N atoms in the chelate site of another 2,2′:6′,4″-terpy in the distorted trigonal-planar geometry. In complex 2, the Cu(I) atom is coordinated by one N atom in the terminal site of 2,2′:6′,4″-terpy, two N atoms in the chelate site of another 2,2′:6′,4″-terpy and one O atom of ClO4− anion in the distorted trigonal–pyramidal geometry. In both of complexes 1 and 2, two Cu(I) atoms are bridged by two 2,2′:6′,4″-terpy in the head-to-tail fashion to form dinuclear Cu(I) complexes with a rectangular [Cu2(2,2′:6′,4″-terpy)2]2+ framework. In contrast, the reaction of [Cu(MeCN)4]PF6 with 2,2′:6′,4″-terpy in MeOH/CHCl3 under C2H4 afforded 1D Cu(I) coordination polymer {[Cu2(2,2′:6′,4″-terpy)2(C2H4)](PF6)2•CHCl3•MeOH}n (3). One Cu(I) atom is coordinated by four N toms in the chelate sites of two 2,2′:6′,4″-terpy in the head-to-head fashion to form a distorted tetrahedral geometry. The other Cu(I) atom is coordinated by two N toms in the terminal sites of two 2,2′:6′,4″-terpy in the tail-to-tail fashion and the CC bond of C2H4 to form a trigonal-planar structure. These Cu(I) atoms are in turns bridged by 2,2′:6′,4″-terpy in the two kinds of head-to-head and tail-to-tail fashions to form a unique 1D helical chain structure. When the complex 2 was dissolved in MeCN and the resultant red-brown solution was diffused with diethyl ether, Cu(I) coordination polymer {[Cu2(2,2′:6′,4″-terpy)2(MeCN)2](ClO4)2}n (4) was collected. The Cu(I) atom is coordinated by two N atoms in the chelate site of 2,2′:6′,4″-terpy, one N atom in the terminal site of another 2,2′:6′,4″-terpy and one N atom of MeCN in the distorted tetrahedral geometry. The Cu(I) atoms are in turns bridged by 2,2′:6′,4″-terpy in the head-to-tail fashion to form a unique 1D helical chain structure.