Some complexes of titanium isopropoxide, titanium ethoxide, aluminum isopropoxide, tantalum isopropoxide, and zirconium isopropoxide with ethylenediamine (en) are described. Two complexes of titanium isopropoxide with ethylenediamine, i.e. Ti(OPri)4,en and Ti2(OPri)8,en, were established by cryoscopic, X-ray powder photograph, and phase rule studies. The structure and stability of these complexes is discussed. Also isolated were Ti2(OEt)8,en; Zr2(OPri)8,en; Ta2(OPri)10,en, and Al2(OPri)6,en. Cryoscopic studies on the aluminum complex suggested that an octameric complex, Al8(OPri)24, (en)4, is present in equilibrium with the dimer. The structural implications of the existence of these complexes are discussed.Phase studies on the binary systems containing titanium tetraisopropoxide and pyridine, diethylamine, or tert-butyl acetate gave no clear indication of complex formation.