2 Homometallic Alkoxides

260 Alkoxo and Aryloxo Derivatives of Metals
Figure 4.28 Structure of
[Ce⊲OBu t ⊳2⊲NO3⊳2⊲Bu t OH⊳2]
(H atoms omitted).
Figure 4.29 Structure of [Ce2f -
OC2H4N⊲Me⊳C2H4NMe2g2⊲OPr i ⊳6]
(H atoms omitted).
(av. 2.322 ˚A vs 2.041 ˚A) and more acute Ce � OC angles (av. 140 Ž vs 173.5 Ž ). Although
[Ce(OBu t ⊳2⊲OCBu t 3 ⊳2] was unstable the Ce(III) compound [Ce2⊲ -OBu t ⊳2⊲OCBu t 3 ⊳4]
was isolated and characterized. 123 The molecule has the familiar pseudo-tetrahedral
bridged structure with the less bulky tert-butoxo ligands taking the bridging
positions (data in Table 4.7). The use of the aminoalcohol Me2NC2H4N(Me)C 2H4OH
gave rise to the centrosymmetric dimer [Ce2f -OC2H4N(Me)C 2H4NMe2g2⊲OPr i ⊳6]
in which all the isopropoxo ligands occupy terminal positions and the
tridentate functionalized alkoxo group acted as a bridging chelating ligand
giving seven-coordinated Ce(IV) (Fig. 4.29). 124 The novel eight-coordinated Ce(IV)