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We report on the synthesis and characterisation of the alkali metal 5, 5'‐bistetrazolate (BT2–) salts Li2BT (1), Na2BT (2), K2BT (3), Rb2BT (4) and Cs2BT (5) as well as the mono ammonium (9) and the mono (10) and bis(1‐ethyl‐3‐methylimidazolium) (11) salts of 5, 5'‐bistetrazole. The crystal structures of the hydrates of the alkali metal salts (1h–4h) and hydrate free (9) to (11) are presented. Additionally we present structures of the monocaesium 5, 5'‐bistetrazolate (6) and alternative modifications of the known salts barium (7h) and diammonium (8) 5, 5'‐bistetrazolate. Among the presented compounds are the first reversibly melting 5, 5'‐bistetrazolate salts (10, 11) and also the first ionic liquid on the basis of 5, 5'‐bistetrazole (11). All substances were investigated by NMR and IR spectroscopy, elemental analysis and combined TGA/DSC measurements. Corresponding to our main motive, the evaluation of the coordination behaviour of 5, 5'‐bistetrazole, we give a short summary of the metal 5, 5'‐bistetrazole salts structurally characterised so far.

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Cyclopentadienylidene phosphoranes of the general formula Cpx-PR2-CH3 (1a–d) and anionic derivatives thereof have been investigated as ligands in the coordination sphere of zirconium (R = NMe2, tBu, Ph; Cpx = C5H4, C5Me4, C5H2(CMe2)2CH2). The ligand set includes a full series of neutral and mono-, di-, and trianionic phosphonium ylides, which are formed by successive deprotonation of the PCH3 group. The degree of deprotonation can be controlled by choice of the ylides 1a–d and the zirconium precursor. The resulting zirconium complexes have been analyzed by NMR spectroscopy, elemental analyses, and single-crystal X-ray diffraction analyses. Our findings include the first fully characterized zirconium complex bearing a neutral cyclopentadienylidene phosphorane ligand, [Zr(H3C-P(NMe2)2-C5Me4)(CH2SiMe3)Cl3] (3a). New constrained-geometry complexes with chelating Cpx-phosphonio-alkyl ([Zr(CH2-PtBu2-C5H4)R′3]: 4b, R′ = Bn; 4b′, R′ = CH2SiMe3)) and Cpx-phosphonio-alkylidene ligands ([Zr(CH-PR2-Cpx)(CH2SiMe3)2]: 5a, R = NMe2, Cpx = C5Me4; 5c, R = Ph, Cpx = C5H2(CMe2)2CH2; 5d, R = Ph, Cpx = C5Me4) have been isolated and characterized. [Zr(C-PR2-C5Me4)Bn]2 (6a, R = NMe2) is a rare example of a compound featuring a bridging trianionic phosphonium ylide (phosphonio-alkylidyne) ligand.