2 Homometallic Alkoxides

214 Alkoxo and Aryloxo Derivatives of Metals
Specific conductivity (× 10 7 ohm −1 cm −1 )
320
240
160
80
0
III
II
I
IV
0.4 0.8 1.2 1.6 2.0 2.4
Molar ratio
M(OPri )
M′(OPri ) 4
Figure 3.3 Titration between
M 0 ⊲OPr i ⊳4 and M⊲OPr i ⊳. Curve I: (Ž)
NaOPr i M/4.77 vs Zr⊲OPr i ⊳4.Pr i OH
M/80.49; Curve II: (�) KOPr i M/9.97
vs Zr⊲OPr i ⊳4.Pr i OH M/43.011; Curve
III: (ž) NaOPr i M/9.94 vs Ti⊲OPr i ⊳4
M/37.7; Curve IV: (ð) KOPr i M/9.94
vs Ti⊲OPr i ⊳4 M/37.7.
RO
RO
RO
M
R
O
R
O
R
O
OR
M OR
OR
Figure 3.4 Schematic
representation of a
nona-alkoxodimetallate(IV)
ligand.
manner 188 that suits their preferred coordination states is remarkable. The possibilities
of the alkoxometallate(IV) ligands to function as simpler fM⊲OR⊳5g and fM⊲OR⊳6g 2
also enhance their versatility in a remarkable manner, as revealed by their X-ray
crystal structural studies at an ever-increasing pace since 1984; 217 these have in
general confirmed the conclusions about their plausible structures on the basis of
simpler colligative, spectroscopic, and other physico-chemical studies. A number of
representative examples of these types of tetra-alkoxometallate(IV) (including a few
heterotermetallic) derivatives are listed in Table 3.4. and an attempt is made in the
following paragraphs to rationalize their structural features (see also Chapter 4).