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Synthesis and Crystal Structure of Sr2AlH7:  A New Structural Type of Alkaline Earth Aluminum Hydride

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journal contribution
posted on 19.11.2002, 00:00 by Qing-An Zhang, Yumiko Nakamura, Ken-ich Oikawa, Takashi Kamiyama, Etsuo Akiba
The title hydride and its deuteride were successfully synthesized. The heavy atom structure and hydrogen positions were determined respectively by X-ray powder diffraction and time-of-flight neutron powder diffraction. They crystallize with a new monoclinic structure in space group I2 (No. 5); cell parameters:  a = 12.575(1) Å, b = 9.799(1) Å, c = 7.9911(8) Å, β = 100.270(4)° (hydride), a = 12.552(1) Å, b = 9.7826(8) Å, c = 7.9816(7) Å, β = 100.286(4)° (deuteride), Z = 8. Sr2AlH7 is the first example that consists of isolated [AlH6] units and infinite one-dimensional twisted chains of edge-sharing [HSr4] tetrahedra along the crystallographic c axis.