Entering group, leaving group, and cis effects of alicyclic primary amines in substitution reactions of platinum(II) complexes containing sulfur-bonded dimethyl sulfoxide

Abstract

Series of complexes of the types czs-[Pt(am)2 (DMSO)Cl]Cl, m-[PtCl2(am)(DMSO)], and [Pt((am')(DMSO))((am)Cl)]Cl, where am is an alicyclic primary amine, CnH2n.[NH2 ( = 3-8), am' is cyclopropylamine, and DMSO is dimethyl sulfoxide bonded through the sulfur, have been prepared and characterized. The kinetics of the forward and reverse steps of the process, c/s-[PtCl2(DMSO)(am)] + am Í m-[Pt(am)2(DMSO)Cl] + + Cl" (and also the analogous reaction with cyclopropylamine as entering group), have been studied in methanol at 30.0°at constant ionic strength and the equilibrium constants have been determined. The normal two-term rate law is observed but the first-order (nucleophile-independent) path is of little importance. In addition to the expected dependence of rate on the basicity of the leaving group, a very strong cis effect is observed where the least basic amine produces the most reactive substrate. This cis effect is as dependent on basicity as the leaving group effect. It is concluded that the very strong trans effect of S-bonded dimethyl sulfoxide is due to transition-state stabilization that results from the -acceptor properties of the sulfur in this ligand.

The Crystal Structure of cis-Dichlorobis(dimethylsulfoxide)platinum(II)

“…Although the infrared spectrum indicates a cis configuration, the chemical behavior is more in keeping with a trans configuration (ref. 5, a note added in proof, confirmed the assignment of a cis configuration since the authors had just synthesized the trans isomer). There is general agreement that in the platinum-(11) complexes with one or two dimethylsulfoxide molecules, the ligands are bonded to platinum through sulfur.…”

Synthesis and characterization of poly(amidoamine)-platinum(II) complexes. Detailed speciation by Matrix-Assisted Laser Desorption Ionization Mass Spectrometry

“…In MALDI spectra of 3 and 4 we observed peaks (M + H + ) and (M + Na + ) relative to the starter ligand G 0 (not reported in table, for assignments see Fig. 1 [12]. This second step is very fast in the reactions with chelating ligands of variable complexity [60,61].…”

“…Sulfur bonded DMSO exhibits a fairly large trans effect in square-planar platinum (II) complexes [9][10][11], exploited in inorganic syntheses [12], and a weak trans influence [13]. Interestingly, while compounds containing a single DMSO are quite inert [14], the presence of a second molecule increases the lability for the nucleophilic substitution [15][16][17].…”

“…Interestingly, while compounds containing a single DMSO are quite inert [14], the presence of a second molecule increases the lability for the nucleophilic substitution [15][16][17]. Thus, sulfoxides spanning a mutual cis position display a relevant self-labilization effect, such as in the complex cis-[Pt(DMSO) 2 Cl 2 ] (1) [12]. Organometallic complexes of the same type cis-[Pt(DMSO) 2 (R) 2 ] (R = CH 3 , aryl group) [18] are much more labile, representing the first example of a dissociative pathway for the nucleophilic substitution process in square planar platinum (II) complexes [19,20].…”

trans-Tétrachlorobis(diméthylsulfure)platine(IV)

“…Plusieurs compos6s de coordination du Pt ~x ont &6 obtenus /l partir du cis-dichlorobis(dim&hylsulfoxyde)platine(II). C'est le cas, par exemple, de [Pt { (C H3)280 }4] (C104)2 (Price, Williamson, Schramm & Wayland, 1972), des cis-et trans-[Pt {(CH3)2SO }(picoline-2)C12] (Melanson & Rochon, 1977, 1978b (Braddock, Romeo & Tobe, 1974). Par analogie, on peut envisager la prbparation de compos6s du Pt Iv en utilisant comme r~actif [PtC14{(CH3)2S}2].…”