Reactions of diphosphinohydrazines R-NH-N-(PPh2)(2) (R = tBu (1), Ph2P (3)) with some metalation reagents (Co[N(SiMe3)(2)](2), LiN(SiMe3)(2), La[N(SiMe3)(2)](3), nBuLi, Me Li) were performed. Compound 1 was synthesized by the reaction of Ph2PCl with tert-butylhydrazine hydrochloride in 83% yield. This compound reveals temperaturedependent P-31 NMR spectra due to hindered rotation about the P-N bonds. Complicated redox reaction of 1 with Co[N-(SiMe3)(2)](2) proceeds with cleavage of the P-N and N-N bonds to form a binuclear cobalt complex [Co{HN(PPh2)(2)-kappa P-2,P'}(2)(mu-PPh2)](2) (2) demonstrating a short Co...Co distance of 2.3857(5) angstrom, which implies a formal double bond between the Co atoms. Strong nucleophiles (nBuLi, Me Li) cause, fragmentation of the molecules 1 and 3, while reactions of 3 with lithium and lanthanum silylamides give products of the NNP -> NPN rearrangement [Li{Ph2P(NPPh2)(2)-kappa N-2,N'}(THF)(2)) (4) and [La{Ph2P(NPPh2)(2)-x(2)N,N'}{N(SiMe3)(2)}(2)] (5), respectively. These complexes represent the first examples of a kappa N-2,N' bonding mode for the triphosphazenide ligand [(Ph2PN)(2)PPh2](-). DFT calculations showed large energy gain (52.1 kcal/mol) of the [NNP](-) to [NPN](-) anion rearrangement.