Protonolysis of Dimethylplatinum(II) Complexes:  Primary Attack at Metal or Ligand

Abstract

The complexes [PtMe 2 (DMEP)], 1, and [PtMe 2 (DMPP)], 2 [DMEP, DMPP ) Me 2 N(CH 2 ) n Nd CH-2-C 5 H 4 N, n ) 2, 3, respectively], contain ligands that chelate to platinum through the imine and pyridyl groups, with the tertiary amine group not coordinated. Methyl iodide reacted with complex 1 to give [PtIMe 3 (DMEP)] but reacted with 2 to give a mixture of [PtIMe 3 (DMPP)] and [PtMe 3 (DMPP)]I, indicating the greater ability of DMPP to act as a fac-tridentate ligand. Complex 2 reacted with MeO 3 SCF 3 to form [PtMe 3 (DMPP)][CF 3 SO 3 ] only. The primary reaction of 1 and 2 with HX (X ) Cl, O 2 CCF 3 , or O 3 SCF 3 ) occurred by protonation of the pendant amine, while with excess acid, a methylplatinum bond trans to imine was cleaved selectively. Two products of protonolysis, namely [PtMe(DMEP)][O 3 SCF 3 ], containing mer-tridentate DMEP, and [PtMe(O 2 CCF 3 )(DMEPH)][O 2 CCF 3 ], with a protonated bidentate DMEP ligand, have been characterized by structure determinations, and the reaction pathways have been deduced by monitoring the reactions by 1 H NMR at varying temperature. In the reaction of 2 with HCl, an intermediate hydridoplatinum(IV) complex [PtHClMe 2 (DMPPH)][Cl] was detected and determined to be stable up to -30 °C, when it decomposed to give methane and [PtClMe(DMPPH)][Cl]. NMR spectrum gave the 195 PtH couplings 3 J(PtH a ) )

Synthesis and in vitro reactivity of cis-dichloro-(pyridin-2-ylcarboxaldimine)platinum(II) complexes with DNA

“…Crystallographic data are given in Table 1 3 and selected bond distances and angles shown in Table 2. The nitrogen-platinum bonds of 1.996(3) Å (pyridine) and 1.985(3) Å (imine) are similar to those reported in other iminopyridine platinum systems (34)(35)(36). Slightly longer Pt-N bond distances are observed in related five-coordinate Pt(II) (37,38) and Pt(IV) complexes (39).…”

Synthesis, crystal structures and cytotoxicities of some transition metal complexes with N-[2-{(pyridin-2-ylmethylidene)amino}ethyl]acetamide

“…3). The nitrogen-platinum bonds of 2.017(5) Å (pyridine) and 1.997(5) Å (imine) are similar to those reported in other iminopyridine platinum systems [10,[22][23][24]. The imine C(6)-N(7) distance is 1.286(8) Å and is in the range of accepted carbon-nitrogen double bonds [25].…”

Combined Low Temperature Rapid Scan and1H NMR Mechanistic Study of the Protonation and Subsequent Benzene Elimination from a (Diimine)platinum(II) Diphenyl Complex Relevant to Arene C−H Activation

“…66,67 Other studies also observed hydridoalkylplatinum(IV) species during low-temperature protonation. [68][69][70][71][72] This lead to the assumption of an oxidative addition mechanism of an alkane to the metal, presumably from a 75 With bulky substituent in the ortho position of the diimine ligand, η 2 -benzene coordination appeared rate limiting while in the absence of ortho substituent, the C-H cleavage became the rate determining step. This was explained by steric destabilisation of both the intermediate π-benzene complex and the transition state by the ortho methyl group.…”