A new synthetic procedure developed recently in our laboratories has made possible the synthesis of variety of new complexes of CuCN with diamines. Synthesis was effected by adding the ligand to a solution of CuCN in aqueous sodium thiosulfate. This procedure also provides an alternative pathway to a novel diamine complex reported by us previously, (CuCN)(3)(HMTA)(2) (1) (where HMTA. = hexamethylenetetramine). The other diamine ligands used were 1,4-diazabicyclo[2.2.2]octane (dabco), 1,4-dimethylpiperazine (dmpip), piperazine (pip), 1,4-butanediamine (butda), N,N,N',N'-tetramethylethylenediamine (tetmen), and N-phenylpiperazine (phpip). Complex 2, Cu-2(CN)(3)(dabco-K), crystallizes in the hexagonal space group P6(3) with unit cell dimensions a =8.174(3) Angstrom, c = 8.083(4) Angstrom, and Z = 2. Complex 3, (CuCN)(2)(dmpip), crystallizes in the monoclinic space group C2/m with unit cell dimensions a = 8.812(3) Angstrom, b = 9.631(2) Angstrom, c = 7.266(3) Angstrom, beta = 113.40(1)degrees, and Z = 2. Complex 4, (CuCN)(2)(pip), crystallizes in the monoclinic space group C2/c with unit cell dimensions a = 9.439(3) Angstrom A, b = 10.561(2) Angstrom, c = 8.870(3) Angstrom, beta = 98.32(3)degrees, and Z = 4. Complex 5, Cu-2(CN)(3)(pip-H), crystallizes in the monoclinic space group C2/c with unit cell dimensions a = 20.573(9) Angstrom, b = 8.354(2) Angstrom, c = 15.989(6) Angstrom, beta = 133.70(3)degrees, and Z = 8. Complex 6, (CuCN)2(butda), crystallizes in the monoclinic space group P2(1)/c with unit cell dimensions a = 10.456(2) Angstrom, b = 5.550(1) Angstrom, c = 8.669(3) Angstrom, beta = 106.80(2)degrees, and Z = 2. Complex 7, (CuCN)(2)(tetmen), crystallizes in the orthorhombic space group Cmc2(1) with unit cell dimensions a = 11.889(4) Angstrom, b = 33.380(8) Angstrom, c = 9.012(3) Angstrom, and Z = 12. Complex 8, (CuCN)(phpip), crystallizes in the monoclinic space group P2(1)/c with unit cell dimensions a = 17.8819(3) Angstrom, b = 6.9190(1) Angstrom, c = 8.6972(1) Angstrom, beta = 96.720(1)degrees, and Z = 4.