Crystal structures of N, N¢-dimethyl-N,N¢-bis(pyridine-2-ylmethyl)propanediaminecopper(II) perchlorate ([Cu(LMe2)]-(ClO4)2) 1 and isothiocyanato-N,N¢-dimethyl-N,N¢-bis(pyridine-2-ylmethyl)propanediaminecopper(II) perchlorate ([Cu(NCS)-(LMe2)]ClO4) 2 have been reported. Each of the N-methyl groups is placed at a trans-and a cis-configuration for [Cu(LMe2)](ClO4)2 and [Cu(NCS)(LMe2)]ClO4, respectively. This would be a reason why a distortion of the complex cation was released to re-bind LMe2 with

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... Cu(II) after the dissociation of LMe2 from [Cu(LMe2)] 2+ ; as a result, the isothiocyanate ion strongly coordinated to [Cu(LMe2)] 2+ . When the two N-methyl groups were replaced at two N-ethyl groups, which might make a large steric hindrance in a peripheral ligand of Cu(II), it is interesting to investigate the configuration of the N-ethyl groups for N, N¢-diethyl-N,N¢-bis(pyridine-2-ylmethyl)propanediaminecopper(II) ([Cu(LEt2)] 2+ ). Its crystal structure and preparation have not yet been reported. Therefore, the [Cu(LEt2)] 2+ complex was prepared, and its crystal structure was determined in this work. N,N¢-Bis(pyridine-2-ylmethyl)propanediamine (LH2) was prepared according to a published preparation method. 2,3 The LH2 of a liquid was purified through an amino silica gel (100 -200 mesh, Fuji Silysia Chem., Aichi, Japan) column by an eluent-mixed ethyl acetate with hexane at a volume ratio of 1:1. The ligand N,N¢-diethyl-N,N¢-bis(pyridine-2-ylmethyl) propanediamine (LEt2) was prepared by refluxing a mixture of LH2 (0.08 mol) with ethyl bromide (0.48 mol, Wako) dissolved X-ray Structure Analysis Online A new complex of an isothiocyanato-N,N¢-diethyl-N,N¢-bis(pyridine-2-ylmethyl)propanediaminecopper(II) perchlorate ([Cu(NCS)(LEt2)]ClO4) was prepared. Its crystal structure was determined by single-crystal X-ray diffractometry. [Cu(NCS)(LEt2)]ClO4·0.5H2O crystallized in a monoclinic system, and was characterized thus: C2/c, with a = 20.8501 (10) , b = 17.2174(9), c = 15.0630(7)Å, b = 119.049(3)˚, Z = 8, V = 4727.2(4)Å 3 . The crystal structure was solved by direct methods and refined by full-matrix least squares on F 2 to final values of R1 = 0.0585. Table 1 Crystal and experimental data Chemical formula: C20H29N5CuClO4.5S Formula weight = 542.54 T = 296 K Crystal system: monoclinic Space group: C2/c a = 20.8501(10)Å b = 17.2174(9)Å b = 119.049(3)c = 15.0630(7)Å V = 4727.2(4)Å 3 Z = 8 Dx = 1.525 g/cm 3 Radiation: Mo Ka (l = 0.71069 Å) m(Mo Ka) = 1.1646 mm -1 F(0 0 0) = 2256 Crystal size = 0.10 ¥ 0.10 ¥ 0.10 mm 3 No. of relections collected = 16857 No. of independent relections = 5215 q range for data collections = 1.8 to 27.5D ata/Restraints/Parameters = 5215/0/316 Goodness-of-t on F 2 = 1.056 R indeces [I > (2s(I)]: R1 = 0.0498 R indeces (all data): R1 = 0.0585, wR2 = 0.1188 (D/s)max = 0.000 (Dr)max = 0.76 eÅ 3 (Dr)min = -0.64 eÅ 3 Measurement: Rigaku RAXIS IV Program systems: CrystalStructure3.8, SHELXL97 Structure determination: SIR2002 CCDC deposition number: 827772 Fig. 1 Chemical diagram of the title compound.