We study the relationship between Schechter's methods of complex inter
polation and the so called commutator estimates. We obtain new commuta
tor theorems and prove characterizations of the Domain and Range space
s associated with the corresponding quasilogarithmic operator. Our met
hods also provide a new approach to known results, including the highe
r order commutator theorems for the complex method recently obtained b
y R. ROCHBERG.