¹⁹⁵Pt and ¹H NMR study of the products of hydrolysis of Pt(L)X₂, where L is an ethylenediamine derivative, and the crystal structure of [Pt(N,N‐dimethylethylenediamine) (μ‐OH)]₂ (NO₃)₂

Abstract

The hydrolysis reactions of complexes of the type Pt(L)X, where L is ethylenediamine (en), N, Ndimethylethylenediamine (N,N-Me,en), N,N-dimethylethylenediamine (N,N'-MeZen) and N,N,N',N'tetramethylethylenediamine (Me,en) were studied. The halo ligands were removed by precipitation with AgNO, and the pH of the resulting filtrate, which was about 2, was adjusted to 5.8 (pD = 6.2). The study of the products formed was carried out by multinuclear NMR spectroscopy. The 195Pt NMR spectra showed the presence of several hydrolysed products, especially with en. The hydroxo-bridged dimer can be synthesized in a pure state with all the ligands except en. The results on the latter ligand contradict the published results on the synthesis of the en hydroxo-bridged dimer whose biological properties were studied. When Pt(L)I, is used as starting material a small quantity of chloro species was always observed, indicating that the reactant contained a small quantity of Pt(L)ICI. The crystal structure of the [ Pt(N,N-Me,en)(p-OH)] ,(NO,), dimer was determined. The compound belongs to the R 1 / c space group, with a = 8.262(5), b = 10.960(8), c = 11.405(8), fl = 121.07(5)", Z = 2 and penle = 2.720 mg m-3. The results showed that this is the trans isomer with an inversion centre between the two Pt atoms. There is a considerable strain inside the four-membered ring, as shown by the reduced internal angles 0-Pt-0' = 79.1(6)" and Pt--O-Pt' = 101.q6)".

Bowl-Shaped and Highly Inert Bis(μ-hydroxo)platinum(II) Dimer

“…The σ-donor strength of nitrogen ligands is much lower, and consequently the known (“N 2 ”)Pt II (“O 2 ”)Pt II (“N 2 ”) structures are planar or nearly so. The deviation from planarity is smaller than 15° in [{Pt(NH 3 ) 2 (μ-OH)} 2 ] 2+ , [{Pt(N,N-Me 2 en)(μ-OH)} 2 ] 2+ , [{Pt(phen)(μ-OH)} 2 ] 2+ , [{Pt(bipy)(μ-OH)} 2 ] 2+ , [{Pt(NO 2 ) 2 (μ-OH) 2 } 2 ] 2- , and [{Pt(N,N‘-disubstituted diimine)(μ-OH)} 2 ] 2+ …”

On the interrelationship of μ-OH bridged dimers, trimers, and tetramers of (en)PtII and their Ag+ adducts

“…With this finding in mind, we compared 195 Pt NMR chemical shifts of a series of l-OH Pt dimers (Table 4). [25][26][27][28] It is obvious that despite the identical donor atoms (N), the 195 Pt NMR resonances are spread out over a 400 ppm 25 The chemical shift of the Pt 2 Ag compound 1, obtained in the presence of excess AgNO 3 in D 2 O, was −1462 ppm. This lowfield shift of ca.…”