The compound (±)-cis-α-[Co(dmtrien)(NO2)2]Cl·0.5H2O 1 has been found to crystallize as a kryptoracemate in the space group C2 (Z = 4) with a racemic pair as the asymmetric unit, whereas (±)-cis-α-[Co(dmtrien)(NO2)2]I 2 crystallizes as a simple racemate, as expected (dmtrien = 3,6-dimethyl-3,6-diazaoctane-1,8-diamine). For 1 the two cations in the asymmetric unit had the conformations Î(λδλ), Co(1), and Î(δλδ), Co(2), and those of the chiral, methylated, nitrogens of Co(1) are (S,S) while those of Co(2) are (R,R). Compound 2 crystallizes as a racemate in the space group Pccn (Z = 8); the anions are in a general position but there are two half cations sitting at two-fold axes of the space group. For 1, Co(1) and Co(2) cations form separate spiral strings which extend through the length of the a axis, and these strings are held together by hydrogen bonds to the anions and waters of crystallization. Each string contains, exclusively, cations of single chirality and layers of homochiral strings define the ab plane of the crystals. Each layer is of opposite chirality to the pair of adjacent ones. In 2 the packing is different in that there are strings made exclusively of either Co(1) or Co(2) running along the diagonal of the bc plane, as well as [âCo(1)âCo(2)âCo(1)âCo(2)â]n . . . strings running parallel to the c axis.
化合物 (±)-cis-α-[Co(dmtrien)(
NO2)2]Cl·0.5H2O 1 已被发现在空间群 C2 (Z = 4) 中以
氪外消旋体形式结晶,并具有外消旋对作为不对称单元,而 (±)-cis-α-[Co(dmtrien)( )2]I 2 结晶为简单的外消旋体,如预期的那样 (dmtrien =
3,6-二甲基-3,6-二氮杂
辛烷-1,8-二胺)。对于 1,不对称单元中的两个阳离子具有构象 δ(δδδ)、Co(1) 和δ(δδδ)、Co(2) 以及手性构象Co(1) 的甲基化氮为 (S,S),而 Co(2) 的氮为 (R,R)。化合物 2 在空间群 Pccn (Z = 8) 中作为外消旋体结晶;阴离子处于一般位置,但有两个半阳离子位于空间群的两倍轴上。对于 1,Co(1) 和 Co(2) 阳离子形成独立的螺旋线,延伸穿过 a 轴的长度,并且这些线通过与阴离子和结晶
水的氢键结合在一起。每条线仅包含单一手性的阳离子,并且同手性线的层定义了晶体的 ab 平面。每层都与相邻层具有相反的手性。在 2 中,封装的不同之处在于,有专门由 Co(1) 或 Co(2) 组成的字符串,它们沿 bc 平面的对角线延伸,以及 [−Co(1)−Co(2) )→Co(1)→Co(2)→]n . . .与 c 轴平行的弦。