The structure of K 2Er(NO 3) 5

Abstract

The structure of K 2Er(NO 3) 5 has been determined by X-ray diffraction. It is monoclinic with a = 7.954(4) A ̊ , b = 11.943(4) A ̊ , c = 14.269(7) A ̊ , ß = 102.85(4) A ̊ , Z = 4, D c = 2.79 g cm −3 and D = 2.659(4) g cm −3 . The space group is C 2 h 5− P2 1/ c. Data was gathered on an automated diffractometer using Mo K α radiation. For 2300 independent reflections a least-squares refinement with anisotropic temperature parameters on all atoms and an extinction correction included yielded R F = 0.049. There is bidentate bonding of the nitrate ions to the Er atom resulting in a coordination number of 10 for the Er atom. The K atoms exhibit 7-fold and 9-fold coordination to the oxygen atoms. The nine coordinated K ion shows bidentate bonding to two nitrate groups and monodentate bonding to five other nitrate groups. The second type of K exhibits bidentate coordination to one nitrate group and monodentate coordination to five other nitrate groups. The supplementary bonding results in a distortion of the nitrate ion. The three oxygen atoms that are bonded only to the 9-fold coordinated K atom have an average bond length of 1.20 Å vs the NO bond length of 1.24–1.29 Å for the oxygens bonded to the Er atom, both K atoms or both a K and Er atom.