The syntheses and structural details of tetraisopropoxyaluminates and tetra-
tert
-butoxyaluminates of nickel(II), copper-(I), and copper(II) are reported. Within the nickel series, either Ni[Al(O
i
Pr)
4
]
2
∙2HO
i
Pr, with nickel(II) in a distorted octahedral oxygen environment, or Ni[Al(O
i
Pr)
4
]
2
∙py, with nickel(II) in a square-pyramidal O
4
N coordination sphere, or Ni[(
i
PrO)(
t
BuO)
3
Al]
2
, with Ni(II) in a quasi-tetrahedral oxygen coordination, has been obtained. Another isolated complex is Ni[(
i
PrO)
3
AlOAl(O
i
Pr)
3
]∙3py (with nickel(II) being sixfold-coordinated), which may also be described as a NiO species trapped by two Al(O
i
Pr)
3
Lewis acid-base systems stabilized at nickel by three pyridine donors. Copper(l) compounds have been isolated in three forms: [(
i
PrO)
4
Al]Cu∙2py, [(
t
BuO)
4
Al]Cu∙2py, and Cu
2
[(
t
BuO)
4
Al]
2
, In all of these compounds, the aluminate moiety behaves as a bidentate unit, creating a tetrahedrally distorted N
2
O
2
copper environment in the pyridine adducts. In the base-free copper(I) tert-butoxyaluminate, a dicopper dumbbell [Cu-Cu 2.687(1) Å] is present with two oxygen contacts on each of the copper atoms. Copper(II) alkoxyaluminates have been characterized either as Cu[(
t
BuO)
4
Al]
2
, {Cu(
i
PrO)[(
i
PrO)
4
Al]}
2
, and Cu[(
t
BuO)
3
(
i
PrO)Al]
2
(copper being tetracoordinated by oxygen) or as [(
i
PrO)
4
Al]
2
Cu∙py (pentacoordinated copper similar to the nickel derivative). Finally, a copper(II) hydroxyaluminate has been isolated, displaying pentacoordinate copper (O
4
N coordination sphere) by dimerization, with the formula {[(
t
BuO)
4
Al]Cu(OH)∙py}
2
. The formation of all of these isolated products is not always straightforward because some of these compounds in solution are subject to decomposition or are involved in equilibria. Besides NMR [copper(I) compounds], UV absorptions and magnetic moments are used to characterize the compounds.