STRUCTURE DETERMINATION OF ADDUCTS OF LEAD(II) IODIDE WITH N-METHYL SUBSTITUTED ETHYLENEDIAMINE AT LOW AND ROOM TEMPERATURES (123, 209 AND 295 K)

Hiroshi Miyamae, Kouichirou Enomoto, Youhei Maruyama and Goro Hihara

Department of Chemistry, Josai University, Saitama 350-0295, Japan (miya@josai.ac.jp)

We have reported that a series of N-methyl substituted ethylenediamines forms 1:1 adducts with lead(II) halides [1]. Among them N,N’-dimethyl- and N,N,N’- trimethyl-ethylendiamine (N,N’-en and N,N,N’-en) with PbI₂ crystallize in tetragonal forming 4₁ spiral with bridging two of iodides. We examined which part contributes mainly volume contraction upon cooling.

X-ray data were taken at three different temperatures, 296, 209 and 123K. The variation in cell volume and axes are gathered in Table 1. The cell parameters do not vary linearly on cooling, especially for N,N,N’-en. However, the contraction could relate to reduction of the nonbonding contacts between the spirals or period of a spiral (Fig. 1). Thus it appears that the ordinal bonds are quite rigid for temperature variation.

References

1 H. Miyamae, Y. Hatanaka, Y. Iijima, G. Hihara, and M. Nagata, AsCA Program Abstracts, 16S 44, 1992.

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Fig. 1. Crystal packings viewed along a for PbI₂- NNN'en (a) and PbI₂-NN'en (b) at 123K.