This report deals with the chemistry of V-C functionalitiesanchored to a quasi-planarO
4 matrix represented here by the[
p-Bu
t-calix[4]-(OMe)
2(O)
2]
2-macrocycle. The startingmaterial[
p-Bu
t-calix[4]-(OMe)
2(O)
2V-Cl],
2, has been converted into the correspondingalkyl
and aryl derivatives[
p-Bu
t-calix[4]-(OMe)
2(O)
2V-R](R = Me,
3; R = CH
2Ph,
4; R=
p-MeC
6H
4,
5) byconventional procedures. The structure of
5 reveals theself-assembling ofthe monomeric unit into a columnar arrangement with the
p-tolyl substituent functioningas a guest moiety in a neighboring unit. Complexes
3-
5 undergo migratory insertionreactions with CO
and Bu
tNC to the corresponding
2-acyls[
p-Bu
t-calix[4]-(OMe)
2(O)
2V(
2-COR)] (R = Me,
6; R = CH
2Ph,
7)
and
2-iminoacyls[
p-Bu
t-calix[4]-(OMe)
2(O)
2V{
2-C(NBu
t)R}] (R = Me,
8; R =CH
2Ph,
9; R =
p-MeC
6H
4,
10), thereaction with CO beingstrongly dependent on the R substituent. The structural model forthe hexacoordinateintermediate leading to the inserted product is exemplified by thed
2 high-spin[
p-Bu
t-calix[4]-(OMe)
2(O)
2V(Cl)(CNBu
t],
11,
and proves the presence of four available orbitals atthemetal for driving the reactivity in the[
p-Bu
t-calix[4]-(OMe)
2(O)
2V]fragment. The bondingmode of the organic functionalities at the metal
and the conversion ofthe alkyl substituentinto the
2-acyl have been inspected by extendedHückel calculations. The oxidativedemethylation of
3 and 5 by a controlled amountof iodine opened an interesting syntheticroute to the corresponding vanadium(IV) organometallic derivatives[
p-Bu
t-calix[4]-(OMe)(O)
3V-X] (X = Cl,
12; X =
p-MeC
6H
4,
13). Astructural report on
2,
5,
and 9 isincluded.