GROUP 1B ORGANOMETALLIC CHEMISTRY. PART 25. CRYSTAL AND MOLECULAR STRUCTURE OF 1,2,3;1,4,5;2,3,6;4,5,6-TETRAKIS-μ3-2-DIMETHYLAMINOPHENYL-2,5;3,4-BIS-μ2-# 4-TOLYLETHYNYL-OCTAHEDRO-HEXACOPPER(I)