Dimeric Pd(II) and Pt(II) chloride organometallics with 2-phenylpyridine and their solvolysis in dimethylsulfoxide

• [M(2-phenylpyridine*)Cl]2 (M = Pd, Pt) remain dimeric in DMF.
• [Pd(2-phenylpyridine*)Cl]2 and [Pt(2-phenylpyridine*)Cl]2 are differently cleavaged in DMSO.
• [Pd(2-phenylpyridine*)(DMSO)2]+[Pd(2-phenylpyridine*)Cl2]− ionic pair appears in DMSO.

Pd(II) and Pt(II) chloride organometallics with the deprotonated, N(1), C(2′)-chelating form of 2-phenylpyridine (2ppy*), i.e. [Pd(2ppy*)(μ-Cl)]2 (1) and [Pt(2ppy*)(μ-Cl)]2 (2), were studied by 1H, 13C, 15N, and 195Pt NMR in DMF-d7 and by 15N CP/MAS in the solid state. Both dimers immediately decompose in DMSO-d6, however, the products of this process are entirely different for 1 and 2. The cleavage of 1 is unusual among all described [M(2ppy*)(μ-X)]2 dimeric compounds as it yields, most likely, the [Pd(2ppy*)(DMSO-d6)2]+ [Pd(2ppy*)Cl2]− ionic pair, whereas 2 is known to undergo a more classical conversion into trans(S,N)-[Pt(2ppy*)(DMSO-d6)Cl]. The conclusions formulated for the above ionic pair were supported by quantum-chemical NMR calculations, calibrated specifically for this class of compounds (geometry optimization tested on molecular cluster, calibration of exact-exchange admixture in the PBE0 functional). The proposed computational approach is shown to be valid and suitable also for similar systems.

[Pd(2-phenylpyridine*)(μ-Cl)]2 undergoes in DMSO unusual solvolysis to the [Pd(2ppy*)(DMSO)2]+ [Pd(2ppy*)Cl2]− ionic pair.Figure optionsDownload as PowerPoint slide