Preparation and reactions of methylpalladium(II) and -platinum(II) azido complexes the crystal structure of trans-PdMe(N3)(PMe3)2 and trans-PdMe[CN4(C6H11)](PMe3)2

Article abstract of DOI:10.1016/S0022-328X(96)06908-2

PdMe(OCOCF₃)(tmeda) (tmeda = N,N,N′,N′-tetramethylethylenediamine) reacts with NaN₃ to give PdMe(N₃)(tmeda) (1). The tmeda ligand in complex 1 is easily replaced by addition of phosphine or amine ligands such as PMe₃, bis(diphenylphosphino)methane (dppm), 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp) and 2,2′-bipyridine (bpy) to give the corresponding palladium(II) azido complexes with the phosphine or amine ligand, PdMe(N₃)L₂ (2: L = PMe₃; 3: L₂ = dppm; 4: L₂ = dppe; 5: L = dppp; 6: L₂ = bpy). The platinum(II) azido complex, trans-PtMe(N₃)(PMe₃)₂ (8), is obtained from ligand exchange of PtMe(N₃)(COD) (7) by PMe₃. The methylpalladium(II) and -platinum(II) azido complexes are isolated in high yields and are thermally stable in the solid state as well as in solution. X-ray diffraction analysis of 2 shows the structure which has a distorted square planar coordination around the Pd center with a Pd-N(azido group) bond distance of 2.132(9) A. Reactions of 2 and of 8 with an equal amount of tert-butyl, cyclohexyl, and 2,6-dimethylphenyl isocyanides cause 1,3-dipolar addition of the isocyanides to the azido ligand to give the complexes, trans-MMe[CN₄(R)](PMe₃)₂ (M = Pd, R = C(CH₃)₃ (9), C₆H₁₁, (10), C₆H₃-Me₂ (11); M = Pt, R = C(CH₃)₃ (12)) with a five-membered heterocyclic ring (C-coordinated tetrazolato group). The molecular structure of 10 determined by X-ray diffraction study displays a slightly distorted square planar coordination around the Pd center with a five-membered heterocyclic ring. Bond parameters indicate localization of π-electron density in the C-N bond and a delocalization of the negative charge over the other three nitrogen atoms. Reactions of complex 2 with protonating agents such as benzenthiol and phenylacetylene are also described.