2 Homometallic Alkoxides

140 Alkoxo and Aryloxo Derivatives of Metals
Ln⊲OBu t ⊳3 C 4LiBu t C 2TMEDA pentane
! [Li⊲tmeda⊳2][LnBu t 4 ] C 3LiOBut965,966
⊲2.304⊳
where Ln D Er, Lu.
Ln⊲OBu t ⊳3 C 3AlMe3 ! [Lnf -OBu t ⊳⊲ -Me⊳AlMe2g3] ⊲2.305⊳
where Ln D Y, Pr, Nd. 966a
Out of the above, the lutetium derivative [Li⊲tmeda⊳2][LuBut 4 ] has been characterized
X-ray crystallographically.
The following two reactions represent an efficient synthetic route to organometallic
compounds of highly oxidizing Ce(IV).
Ce⊲OPr i ⊳4 C 3
2Mg⊲C5H5⊳2 Ce⊲OPr i ⊳4 C 3Me3SnC5H5
! ⊲C5H5⊳3Ce⊲OPr i ⊳ C 3
2 Mg⊲OPri ⊳2 967
! ⊲C5H5⊳3Ce⊲OPr i ⊳ C 3Me3SnOPr i968
⊲2.306⊳
⊲2.307⊳
A number of interesting organometallic compounds of cerium have also been reported
as arising from the reactions of Ce⊲OPr i ⊳4.Pr i OH or Ce⊲OPr i ⊳4 with cyclooctatetraene
⊲C8H8⊳ in the presence of AlEt3. The composition of the final product depends 967 on the
reaction conditions (Eqs 2.308–2.310):
CAlEt3/3C8H8
toluene,140 Ž C
! Ce2⊲C8H8⊳3 C 10AlEt2⊲OPr i ⊳ C 2C2H6
(2.308)
C8AlEt3/2C8H8
Ce⊲OPr i ⊳4Pr i OH ! 2⊲C8H8⊳Ce⊲ -OPr i ⊳2AlEt2 (2.309)
toluene,100 Ž C
C10AlEt3⊲excess⊳/4C8H8
⊲solvent⊳
110 Ž C
! 2Ce⊲C8H8⊳2 C 10AlEt2⊲OPri⊳ C 2C2H6 C 8[Et] (2.310)
where 8[Et] D eight ethyl radicals.
Methyllithium reacts with U⊲OCHBu t 2 ⊳4 in hexane to afford heterobimetallic lithium
uranium methyl alkoxide, 229 the structure of which is based upon two-coordinate
lithium and five-coordinate uranium with the geometry of uranium being near that
of a square pyramid with the methyl group occupying the apical site:
U⊲OCHBu t 2 ⊳4 C LiMe hexane
! ⊲Bu t 2 CHO⊳2MeU⊲ -OCHBu t 2 ⊳2Li ⊲2.311⊳
The type of reactions illustrated in Eqs (2.302)–(2.305), (2.309), and (2.311) assume
special significance for their role in the development of novel organoheterometallic
alkoxide chemistry (Chapter 3, Section 2.1.5.1).
The interactions of early 3d transition metal alkoxides with lithium alkyls, Grignard
reagents, or dimethylzinc yield interesting homo- and heteroleptic alkyls as shown in