Nine compounds containing high-nuclearity [Cu(n)X(2n+2)]2- (n = 4, 5 or 7; X = Cl or Br) quasi-planar oligomers.

The structures of seven A(2)Cu(4)X(10) compounds containing quasi-planar oligomers are reported: bis(1,2,4-trimethylpyridinium) hexa-μ-chlorido-tetrachloridotetracuprate(II), (C(8)H(12)N)(2)[Cu(4)Cl(10)], (I), and the hexa-μ-bromido-tetrabromidotetracuprate(II) salts of 1,2,4-trimethylpyridinium, (C(8)H(12)N)(2)[Cu(4)Br(10)], (II), 3,4-dimethylpyridinium, (C(7)H(10)N)(2)[Cu(4)Br(10)], (III), 2,3-dimethylpyridinium, (C(7)H(10)N)(2)[Cu(4)Br(10)], (IV), 1-methylpyridinium, (C(6)H(8)N)(2)[Cu(4)Br(10)], (V), trimethylphenylammonium, (C(9)H(14)N)(2)[Cu(4)Br(10)], (VI), and 2,4-dimethylpyridinium, (C(7)H(10)N)(2)[Cu(4)Br(10)], (VII). The first four are isomorphous and contain stacks of tetracopper oligomers aggregated through semicoordinate Cu···X bond formation in a 4(5/2,1/2) stacking pattern. The 1-methylpyridinium salt also contains oligomers stacked in a 4(5/2,1/2) pattern, but is isomorphous with the known chloride analog instead.