The coordination complex [Ni(en)3]2+(NO3-)2 (en = 1,2-diaminoethane) undergoes a sharp reversible displacive phase transition at -109 K, changing space group from P6322 above the transition temperature to P6522 below. The phase change is accompanied by a tripling of the c axis on cooling, resulting in an easy detection of the transition in images from area-detector diffractometers. The transition has been followed using a Nonius KappaCCD and a Bruker SMART APEX CCD. Data sets were collected over the temperature range 100-113 K and integrated using the low-temperature orientation matrix. Reflections with ≠ 3n show a smooth and rapid decrease in intensity to zero on warming from 106.5 to 111 K. The results are reproducible to within ±2 K in two laboratories and suggest that this compound may be useful as a liquid-nitrogen cryo-calibrant for diffraction instruments equipped with area detectors.
Reversible displacive phase transition in [Ni(en) 3] 2+(NO 3 -) 2: A potential temperature calibrant for area-detector diffractometers / L. J. Farrugia, P. Macchi, A. Sironi. - In: JOURNAL OF APPLIED CRYSTALLOGRAPHY. - ISSN 0021-8898. - 36:1(2003), pp. 141-145.
Reversible displacive phase transition in [Ni(en) 3] 2+(NO 3 -) 2: A potential temperature calibrant for area-detector diffractometers
A. SironiUltimo
2003
Abstract
The coordination complex [Ni(en)3]2+(NO3-)2 (en = 1,2-diaminoethane) undergoes a sharp reversible displacive phase transition at -109 K, changing space group from P6322 above the transition temperature to P6522 below. The phase change is accompanied by a tripling of the c axis on cooling, resulting in an easy detection of the transition in images from area-detector diffractometers. The transition has been followed using a Nonius KappaCCD and a Bruker SMART APEX CCD. Data sets were collected over the temperature range 100-113 K and integrated using the low-temperature orientation matrix. Reflections with ≠ 3n show a smooth and rapid decrease in intensity to zero on warming from 106.5 to 111 K. The results are reproducible to within ±2 K in two laboratories and suggest that this compound may be useful as a liquid-nitrogen cryo-calibrant for diffraction instruments equipped with area detectors.Pubblicazioni consigliate
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