Reaction of TiCl2(Me(2)Calix) with 2 equiv of LiNHNRR' afforded the corresponding terminal hydrazido(2-) complexes Ti(NNRR')(Me(2)Calix) (R = Ph, R' = Ph (1) or Me; R = R' = Me (3)) which were all structurally characterized. The X-ray structure of Ph2NNH2 is reported for comparison. Compound 1 was, also prepared from Na-2[Me(2)Calix] and Ti(NNPh2)Cl-2(py)(3). Reaction of ZrCl2(Me(2)Calix) with 2 equiv of LiNHNR2 afforded only the bis(hydrazido(1-)) complexes Zr(NHNR2)(2)(Me(2)Calix) (R = Ph or Me). Treatment of Ti(NNMe2)(Me(2)Calix) (3) with Mel gave the zwitterionic hydrazidium species Ti(NNMe3)(MeCalix) (6) via a net isomerization reaction which was found to be catalytic in Mel. The corresponding reaction of 3 with CD(3)l gave Ti(NNMe2CD3)(MeCalix) (6-d(3)) with concomitant elimination of Mel. Reaction of 3 with 1 equiv of MeOTf gave [Ti(NNMe3)(Me(2)Calix)][OTf] (7-OTf) which in turn reacted with (BU4NI)-B-n to form 6 and Mel. Addition of PhCHO to 3 gave the mu-oxo dimer [Ti(mu-O)(Me(2)Calix)](2) and benzaldehyde-dimethylhydrazone, Reaction of either 3 or 6 with (BuNCO)-Bu-t gave the zwitterionic species Ti{(BuNC)-Bu-t(NNMe3)O}(MeCalix) (10) which has been crystallographically characterized. Compound 10 is the formal product of insertion of an isocyanate into the Ti=N-alpha bond of a titanium hydrazide or hydrazidium species (Me(2)Calix or MeCalix = dianion or trianion of the di- or monomethyl ether of p-tert-butyl calix[4]arene, respectively).