Novel co-ordination numbers in scandium(III) and yttrium(III) nitrato-comlplexes. X-ray crystal structures of Sc(NO3)3.2N2O4 and Y(NO3)3.2N2O4

Highly Hydrated Cations: Deficiency, Mobility, and Coordination of Water in Crystalline Nonahydrated Scandium(III), Yttrium(III), and Lanthanoid(III) Trifluoromethanesulfonates

“…[36,37] With bidentate ligands, scandium(iii) coordinates eight oxygen atoms in coordination polyhedra described as distorted dodecahedral or irregular bicapped trigonal prisms; [38] this occurs, for example, in the HSc(O 2 C 7 H 5 ) 4 compound with a mean ScÀO bond length of about 2.21 . [39] Ninefold oxygen coordination also requires bidentate ligands, [20,31] even though a ninefold-hydrated [Sc(H 2 O) 9 ] 3 + ion is assumed to exist, based on a previous crystal-structure determination for nonaaquascandium(iii) trifluoromethanesulfonate. [8] In this hydrate, the site symmetry is consistent with a tricapped trigonal prism around the central scandium(iii) ion with six short ScÀO p bond lengths of 2.171(6) , and three ScÀO c distances reported to be 2.47 (2) .…”

“…[18] The mean M III ÀO distance from crystal structures of the trifluoromethanesulfonate salts of the hydrated d 0 ions of Group 3 (2.55, 2.40 and 2.28 for M = La, Y and Sc, respectively) changes substantially for nine coordination in the TTP configuration. [10,19,20] However, in aqueous solution only the largest ion, lanthanum(iii), coordinates nine water molecules; [21] the yttrium(iii) ion coordinates eight, [19] while the hydration number of the relatively small scandium(iii) ion is probably around seven, [1] with the mean MÀO distances being 2.54-2.58, [21] 2.37 [19] and 2.17-2.18 , [22,23] respectively, in asymmetric radial distributions.…”

What is the coordination number of vanadium in vanadyl nitrate, VO(NO3)3? A study of its molecular structure in the gas phase by electron diffraction and ab initio calculations

“…3 In [Sc(NO 3 ) 5 ] 2Ϫ the Sc is 9-coordinate, as one of the nitrate groups is monodentate, whereas in the valence-isoelectronic species [Y(NO 3 ) 5 ] 2Ϫ all the nitrate groups are bidentate. 4 Only monodentate nitrate ligands are found in [Au(NO 3 ) 4 ] Ϫ . 5 These examples show that it is not generally possible to deduce the type of coordination in a nitrato complex just from its stoichiometry.…”

A comparison of the structural chemistry of scandium, yttrium, lanthanum and lutetium: A contribution to the group 3 debate

“…The complex (NO)2[Sc(NO3)5] again has a structure based on a trigonal bipyramid (Figure 12c). There are four bidentate nitrates with one of the equatorial nitrates being monodentate, leading to nine coordination, whereas in the yttrium analogue the five nitrate groups are symmetrically bidentate, giving an overall coordination number of ten [79] similar to that of the lutetium complex. In Rb2[Sc(NO3)5], however, there are three bidentate and two monodentate nitrates, resulting in eight coordinate scandium [80].…”