The water-soluble four- and five-coordinate diazido-platinum(II) complexes cis-[Pt(N₃)₂(PTA)₂] (1) (PTA = 1,3,5-triaza-7-phosphaadamantane), cis-[Pt(N₃)₂(Me-PTA)₂]I₂ (2) (Me-PTA = N-methyl-1,3,5-triaza-7-phosphaadamantane cation) and [Pt(N₃)₂(PTA)₃] (3) were obtained by reactions of cis-[Pt(N₃)₂(PPh₃)₂] with PTA or [Me-PTA]I in dichloromethane. [2 + 3] cycloadditions of 1 with organonitriles NCR gave the bis(tetrazolato) complexes trans-[Pt(N₄CR)₂(PTA)₂] (R = Ph (4), 4-ClC₆H₄ (5) or 3-NC₅H₄ (6)), the reactions being greatly accelerated by microwave irradiation. 5-R-1H-Tetrazoles N₄CR (R = Ph, 4-ClC₆H₄ and 3-NC₅H₄) were easily liberated from the tetrazolato complexes 4–6 and isolated in high yields, in a single-pot process, upon reaction with aqueous diluted HCl, with concomitant formation of the water soluble cis-[Pt(Cl)₂(PTA-H)₂] complex 7. Alternatively, in a less convenient method, the tetrazoles could be liberated on reaction of 4–6 with propionitrile which also leads to the dicyano trans-[Pt(CN)₂(PTA)₂] complex 8. The compounds were characterized by IR, ¹H, ¹³C and ³¹P{¹H} NMR spectroscopies, FAB⁺ -MS or ESI-MS, elemental analyses and (for 1 and 4) also by X-ray diffraction.

[2 + 3] Cycloaddition reactions of the diazidoplatinum(II) complexes cis-[Pt(N₃)₂(PPh₃)₂] 1 and cis-[Pt(N₃)₂(2,2′-bipy)] 4 with organonitriles NCR 2 give the bis(tetrazolato) complexes trans-[Pt(N₄CR)₂(PPh₃)₂] 3 [R = Me (3a), Et (3b), Pr (3c), Ph (3d), 4-ClC₆H₄ (3e)] and cis-[Pt(N₄CR)₂(2,2′-bipy)] 5 [R = Me (5a), Et (5b), Pr (5c), Ph (5d)]. The reaction of cis-[Pt(N₃)₂(PPh₃)₂] 1 with propionitrile also affords, apart from 3b, the unexpected mixed cyano-tetrazolato complex trans-[Pt(CN)(5-ethyltetrazolato)(PPh₃)₂] 3b′ which is derived from the reaction of the bis(tetrazolato) 3b with propionitrile, with concomitant formation of 5-ethyl-1H-tetrazole, via a suggested unusual oxidative addition of the nitrile to Pt^II. All these reactions are greatly accelerated by microwave irradiation and this method also shows a higher selectivity in the case of the reaction of propionitrile with 1, leading only to the formation of 3b. All the complexes obtained were characterized by IR, ¹H, ¹³C and ³¹P{¹H} (for complexes 3) NMR spectroscopies, FAB-MS and elemental analyses. Complexes 3b′, 3d, 3e and 5d were also characterized by X-ray structural analyses.

The coordinated EtCN in the anionic platinum(II) [Ph₃PCH₂Ph][PtCl₃(EtCN)], the neutral platinum(II) [PtCl₂(EtCN)₂] or the neutral platinum(IV) [PtCl₄(EtCN)₂] complexes undergo [2 + 3] cycloadditions with cyclic non-aromatic nitrones and these reactions are greatly accelerated by microwave irradiation, to give, with a high stereoselectivity, complexes with bicyclic fused oxadiazolines as a racemic mixture in 60–90% yields, while acyclic nitrones are much less reactive and give a mixture of two diastereoisomers in the ratio 1 ∶ 1. The new bicyclic oxadiazoline ligands can be liberated by reaction with a diphosphine. However, with a cyclic aromatic nitrone no cycloaddition is observed and only the product of the nitrile substitution is obtained. All compounds were characterised by elemental analyses, IR, ¹H, ¹³C and ¹⁹⁵Pt NMR spectroscopies.