Transmetalation of a dimeric homotrinuclear zinc(II) complex [(3-MeOsalamo)2Zn3] with Lu3+ and La3+ afforded heterometallic dinuclear [(3-MeOsalamo)ZnLu]3+ and trinuclear [(3-MeOsalamo)2Zn2La]3+ complexes, respectively, whose structures were determined by X-ray crystallography. The transmetalation process was investigated by 1H NMR titrations.