Homoleptic complexes scandium

In 1998, Kempe and coworkers [34] reported the first aminopyridinato rare-earth metal complexes. 4-Methyl-2-[(trimethylsilyl)amino]pyridine(HLl) was utilized in this complex. The reaction of lithiated LI and YCI3 in ether and pyridine led to the ate complex [Y(Ll)4(LiPy)] (Py = pyridine) (1). The complex 1 catalytically mediated a ligand transfer reaction to form [Pd(Ll)2] and [Y(Ll)3(py)] (2) from [Pd(cod)Cl2] (cod = cyclooctadiene). The LI ligand transfer from yttrium to palladium and the regeneration of 1 are significant in the efficient synthesis of the very strained amido palladium complexes (Scheme 2). Lithiated LI underwent a salt metathesis reaction with ScCb, at low temperature in THF, to yield the homoleptic complex [Sc(L1)3] (3) (Scheme 2). 3 is the first reported scandium aminopyridinato complex [35]. 

Synthetic strategies to alkoxide complexes have been covered in full by previous reviews [14]. The silylamide route proved to be an advantageous method of preparation, especially in the case of homoleptic derivatives [15]. The group (IIIA) elements - scandium, yttrium and lanthanum - are considered as lanthanides on the basis of their general chemical similarity to the true lanthanides. 

Studies of the bonding in some transition-metal complexes have identified a similarity between the He(I) photoelectron spectra of three-co-ordinate homoleptic bis(trimethylsilyl) amides of scandium and those of open-shell compounds. The two bands at ionization potential <9 eV were assigned to lone-pair orbitals. Bands corresponding to ionization from the metal 3d orbitals were considered to lie at ionization potentials >9eV or to be masked by the bands resulting from nitrogen lone-pair orbitals (> 8.1 eV). 

Finally some homoleptic alkyne complexes of scandium and some rare earths are known. Tris(phenylethynyl) scandium is formed as a dark brown product after treatment of phenylethyne with butyl lithium at — 78°C in hexane, followed by the addition of scandium trichloride at room temperature. The compound is inflammable in air (Hart and Saran, 1968 Hart et al., 1970). The reaction of the anionic... 

Homoleptic lithium complexes [Li NNE 2]Cl (E = 0, S), containing Juc-coordinating NNE-donor hgands prepared from bis(3,5-dimethylpyrazol-l-yl)methanewith BuLi and alkyl- or aryl-containing isocyanates or isothiocyanates, have been used to synthesize a series of scandium and yttrium complexes. ... 

Otero A, Lara-Sanchez A, Femandez-Baeza J, et al. New achiral and chiral NNE heteroscorpionate ligands. Synthesis of homoleptic lithium complexes as well as halide and alkyl scandium and yttrium complexes. Dalton Trans. 2010 39 930-940. 

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