2 Homometallic Alkoxides

Heterometallic Alkoxides 209
Table 3.2
3d metals
Properties of tetraalkoxoaluminates and allied derivatives of a few later
97
MW
Compound Nature
Volatility
(
found eff Dq
ŽC/mm) (Calc.) (B.M./K) (cm 1 )
Cr[Al(OPri )4]3 Green viscous 190/0.6 838 3.90/100 1527
liquid
(842) 3.92/297
Mn[Al(OPri )4]2 Brown viscous 145/0.6 607 5.95/88
–
liquid
(582) 5.90/297
Fe[Al(OPri )4]3 Brown viscous 130/0.8 1003 5.06/89
–
liquid
(846) 5.39/296
Fe[Al(OPri )4]2 Brown 125/0.8 605 4.53/87
–
semi-solid
(582) 5.06/297
Co[Al(OPri )4]2 Purple liquid 140/0.6 629 4.62/92 873
(586) 4.39/297
Ni[Al(OPri )4]2 Pink liquid 120/0.6 570
(585)
3.29/90
3.39/294
823 (film)
895 (PriOH) 912 (py)
Cu[Al(OPri )4]2 Greenish-blue 135/0.6 604 1.22/87 1380
liquid
(593) 1.64/297
Cr[Al(OPri )3(OMe)]3 Light-green
solid
215/0.8 – 3.84/300 1572
Cr[Al(OPri )2(OMe)2]3 Green solid 255/0.8Ł Cr[Al(OEt)4]3 Green solid 235/0.8
– 3.86/300 1582
Ł Cr[Al(OCH2CF3)4]3 Brown viscous
liquid
120/0.8
– 3.86/300 1577
Ł 1353
(1321)
3.86/300 1520
Cr[Al(OPri )3(acac))]3 Green pasty 140/0.8 967 3.82/300 1675
solid
(962)
Cr[Al(OPri )2(acac)2]3 Green solid 180/0.8Ł 1233 3.83/300 1692
(1082) –
–
Fe[Al(OPri )2(OAmt )2]3 Brown solid 270/0.6Ł 976
(1014)
– –
Ni[Al(OPri )(OBut )3]2 Purple solid 140/0.6Ł 691 3.14/88 736
(670) 3.47/300
Ni[Al(OPri )2(acac)2]2 Brown pinkish 240/0.6
solid
Ł 708 3.28/300 769
(745)
Cu[Al(OCH2CF3)4]4 Blue semi-solid 115/0.5 – 1.72/300 1602
Cu[Al(OPri )(OBut )3]2 Green solid 150/0.5Ł – 1.74/300 1230 (benzene)
1490 (Nujol)
Ł Indicates sublimation.
1 See Section 2 for details of routes listed.
An interesting trend in the ligating behaviour of fAl⊲OR⊳4g can be illustrated by
nickel derivatives. 42 The generally bidentate nature of fAl⊲OR⊳4g , ligands, should be
reflected in the tetrahedral or square planar nature of nickel in NifAl⊲OPr i ⊳4g2.However,
its spectral and magneto-chemical properties appear to reveal a tendency for the nickel
atom to achieve octahedral geometry, possibly by adopting a structure of the type
Nif⊲ -OPr i ⊳3Al⊲OPr i ⊳g2 in which fAl⊲OPr i ⊳4g behaves as a tridentate ligand. Its electronic
spectra (Fig. 3.1) show 2 and 3 bands characteristic of octahedral geometry at
about 13 000 and 24 000 cm 1 . In addition, the appearance of a doublet in the region
17 000–19 000 cm 1 indicates the presence of some tetrahedral species also in equilibrium
with the octahedral one; the octahedral form becomes predominant in isopropyl