2 Homometallic Alkoxides

284 Alkoxo and Aryloxo Derivatives of Metals
Figure 4.39 Structure of [Mo2⊲ -
OPr i ⊳3⊲OPr i ⊳2⊲N2CPh2⊳⊲py⊳] (Hatoms
omitted).
Figure 4.40 Mo2⊲ -C2H2⊳⊲ -
O⊳2O4N2 core structure of [Mo2⊲ -
C2H2⊳⊲ -OPr i ⊳2⊲OPr i ⊳4⊲py⊳2].
of excess acetylene produced [Mo2⊲ -C4H4⊳⊲ -OCH2Bu t ⊳(OCH 2Bu t ⊳5(py)] in which
one Mo is part of a molybdacyclopentadiene moiety and is further bonded to a bridging
Bu t CH2O, two terminal Bu t CH2O ligands and a pyridine whilst the other Mo is bonded
to a bridging Bu t CH2O ligands and -bonds to the metallocycle.
Further research on the carbonylation of Mo2⊲OR⊳6 in the presence of Lewis bases
L gave the dimer [Mo2⊲ -CO⊳⊲ -OPr i ⊳2⊲OPr i ⊳4⊲py⊳2] which has the confacial bioctahedral
structure with -CO and two -OPr i bridges. 234 The pyridine ligands are
trans to the carbonyl ligand. The structure of the mixed ligand (Mo Mo) dimer