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Scandium compounds/complexes, coordination

Scandium is still a neglected element. It is the most expensive metal in its period (caused by the fact that its even distribution in the earth means that there are no rich ores) and its chemistry is virtually exclusively that of the +3 oxidation state, so that it is not classed as a transition metal and is often silent to spectroscopy and not amenable to study by many of the usual spectroscopic tools of the coordination chemist. Chemists have often either tended to assume that complexes of Sc are just like those of the tripositive ions of the transition metals or that they resemble lanthanide complexes. Neither of these assumptions is correct—how incorrect we are now realizing. Scandium chemistry is starting to exhibit characteristics all of its own, and possibly the burgeoning use of scandium compounds in organic synthesis may drive a real expansion of scandium chemistry. [Pg.94]

Both scandium and yttrium form borohydride complexes [M(BH4)3(thf) ] with thf coordinated to the metal.53 In each compound two borohydride groups are bound through three hydride bridges and one borohydride is bound through two hydride bridges. The scandium compound is... [Pg.6]

The tetraphenylporphyrin scandium complexes were previously reported and now crystal structures have been determined for the p-toly derivatives (ttp). Both scandium and yttrium form (ttp)MCl complexes150,151 but whereas the scandium compound is five-coordinate the yttrium compound coordinates solvent molecules forming seven or eight-coordinate complexes. Reaction of (ttp)ScCl with water forms an oxide dimer [Sc(ttp)]20,151 whereas for yttrium the cation [Y(ttp)(H20)3]+ has been observed.152 The structure of [Sc(ttp)]20 is shown in Figure 7, the bridging oxygen is disordered over two sites with 50% occupancy of each site. The reaction of... [Pg.13]

Organolithium compounds of structure 275 can been applied as transfer agents for transition metal ions, for example, as shown in equation 54 for scandium(III) with tetrahedral coordination (276). The structure of these complexes, elucidated by XRD crystallography, shows the transition metals forming part of an anionic entity, paired to solvated lithium cations. Further structural information can be obtained from H, and "B NMR spectroscopies. ... [Pg.380]

The classical tridentate ligand terpyridyl (terpy) forms a nine-coordinate complex with scandium nitrate [Sc(terpy)(N03)3].52 This compound with chelating nitrates exhibits a relatively rare high coordination number for scandium. [Pg.12]

The reaction of scandium triflate with Li[C(PMe2)2SiMe3] gives a six-coordinate complex with a trigonal prismatic environment (12). There is an unusual ScP2C four-membered ring in this compound.158... [Pg.14]


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