Abstract
We have prepared Cm[Au(CN)2]3 · 3H2O and Cm[Ag(CN)2]3 · 3H2O as a part of our continuing
investigations into the chemistry of the
5f-elements’ dicyanometallates. Single crystals of Cm[Au(CN)2]3 · 3H2O were obtained from the
reaction of CmCl3 and KAu(CN)2 under
mild hydrothermal conditions. Due to similarities in size, the related praseodymium compounds were
also synthesized and characterized
for comparison with the actinide systems. The compounds crystallize in the hexagonal space group
P63/mcm, where the curium and the transition metals interconnect through cyanide bridging.
Crystallographic data (Mo Ka, l ¼ 0.71073 A˚ ): Cm[Au(CN)2]3 · 3H2O (1), a ¼ 6.6614(5) A˚ , c ¼
18.3135(13) A˚ , V ¼ 703.77(9), Z ¼ 2; Pr[Au(CN)2]3 · 3H2O (3), a ¼ 6.6662(8) A˚ , c ¼ 18.497(3)
A˚ , V ¼ 711.83(17), Z ¼ 2; Pr[Ag(CN)2]3 · 3H2O (4), a ¼ 6.7186(8) A˚ , c ¼ 18.678(2) A˚ , V ¼
730.18(14), Z ¼ 2. The Cm3+ and/or Pr3+ ions are coordinated to six N-bound CN- groups resulting
in a trigonal prismatic arrangement. Three oxygen atoms of coordinated water molecules tricap the
trigonal prismatic arrangement providing a coordination number of nine for the f-elements. The
curium ions in both compounds exhibit a strong red emission corresponding to the 6D7/2-8S7/2
transition. This transition is observed at 16,780 cm-1, with shoulders at 17,080 and 16,840 cm-1
for the Ag complex, while the emission is red shifted by -100 cm-1 in the corresponding gold
complex. The Pr systems also provide well-resolved emissions upon f–f excitation.