Study on the interaction between [Pt(μ‐Cl)(isopropyl eugenoxyacetate‐1H)]₂ and 1,3‐diisopropylbenzimidazolium bromide

Abstract

The interaction between the dinuclear chelate ring complex [Pt(μ-Cl)( i PrEug)]2 (1) ( i PrEug: deprotonated isopropyl eugenoxyacetate) and 1,3-diisopropylbenzimidazolium bromide ( i Pr2-bimy·HBr) has been studied for the first time. The result shows that the chloride bridges in 1 are easily cleaved by the i Pr2-bimy in the present of base to form a mixture (Phh) of two complexes [PtBr( i PrEug)( i Pr2-bimy)] (2) and [PtCl( i PrEug)( i Pr2-bimy)] (3), and the molar ratio of 2:3 in Phh depends on the used base Ag2O or Na2CO3/NaOOCCH3/NaHCO3/NaOH. The reaction of Phh with NaBr afforded complex 2 with high yield. The structure of 2 was determined by weight method, ESI-MS, IR, 1 H NMR, 13 C NMR, HSQC spectroscopies and single-crystal X-ray diffraction. The NMR and XRD studies also reveal that the introdution of i Pr2bimy leads to a weakening of the Pt-(C9=C10) bond and strengthening of the Pt-C5 bond in 2.

The interaction between [Pt(µ-Cl)(Safrole-1H)]2 and 1,3-diisopropylbenzimidazolium bromide in the presence of Ag2O

“…1), the reaction did not give the expected complex containing i Pr 2 -bimy but the precursor 1 despite the unambiguous reaction phenomenon. The similar result has been observed in the case of using [Pt(µ-Cl)( i PrEug)] 2 instead of complex 1 [10]. These findings affirm that complexes of general formula [PtX(arylolefin)(NHC)] could not be synthesized by the reaction between dimer complex [Pt(µ-Cl)(arylolefin)] 2 and NHC•HX without base.…”

“…It is worthy to note that, when replacing complex 1 in the experiments N o . 5 by its analogue, [Pt(µ-Cl)( i PrEug)] 2 , it also gave the similar result [10]. In the experiments N o .…”

“…As shown in Scheme 1, firstly, the Pt 1 -Cl 1 or Pt 2 -Cl 2 bond weaker than Pt 1 -Cl 2 or Pt 2 -Cl 1 bond in complex 1 [10] are easily cleaved by i Pr 2 -bimy•HBr to form ionic complex ( i Pr 2bimy•H) + [Pt(Br)(Cl)(Saf)] -(P tg ), which is stable in the solution but converts to the starting complex 1 when the solvent is evaporated. Then the cation ( i Pr 2 -bimy•H) + is deprotonated to give NHC, i.e.…”

“…Complex [Pt(µ-Cl)(Saf)] 2 (1) [12] and i Pr 2 -bimy•HBr [10] were synthesized as previously reported.…”

“…Among synthetic methods of Pt(II)-NHC complexes, the procedure starting from simple Pt(II) compounds and azolium salts in the presencet of common bases such as Ag 2 O is the most used [4,9]. Recently, our study on the reaction of [Pt(µ-Cl)( i PrEug)] 2 ( i PrEug: deprotonated isopropyleugenoxyacetate) with 1,3-diisopropylbenzimidazolium bromide ( i Pr 2 -bimy•HBr) with the molar ratio of 1 : 2 using different bases including Ag 2 O, Na 2 CO 3 , CH 3 COONa, NaHCO 3 , NaOH afforded the mixture of [PtCl( i PrEug)( i Pr 2 -bimy)] and [PtBr( i PrEug)( i Pr 2 -bimy)] [10]. In continuation of this research direction, we herein describe in detail the reaction of [Pt(µ-Cl)(Saf)] 2 (1, Saf: deprotonated safrole) and i Pr 2 -bimy•HBr in the presence of Ag 2 O to investigate factors controlling the reaction direction, which could orient for synthesis of complexes of type [PtX(arylolefin)(NHC)].…”