Slippage of #eta#~3-allenyl/propargyl to an #eta#~3-allenyl/propargyl to an #eta#~1 structure and tautomerization of #eta#~1-propargyl to #eta#~1-allenyl in ligand addition and substitution reactions of platinum(II) complexes

摘要

Reactions of [(PPh_3)_2Pt(#eta#~3-CH_2CCPh]OTf with each of Me_3, CO and Br~- result in the addition of these species to the metal and a change in hapticity of the #eta#~3-CH_2CCPh to #eta#~1-CH_2C ident to CPh or #eta#~1-C(Ph)=C=CH_2. Thus, PMe_3 affords [PMe_3)_3Pt(#eta#~1-C(Ph)=C=CH_2)]~+. CO gives both [trans-(PPh_3)_2Pt(CO)(#eta#~1-CH_2C ident to CPh)]~+ and [trans-(PPh_3)_2Pt(CO)(#ETA#~1-C(Ph)=c=ch_2)]~+, and LiBr yields cis-(PPh_3)_2PtBr(#eta#-CH_2C ident to CPh) each lead to tautomerization of #eta#~1-CH_2C ident to CPh to #eta#~1-C(Ph)=C=CH_2, with trans-(PPh_3)_2PtBr(#eta#~1-CH_2C ident to CPh) affording [(PMe_3)_3Pt(#eta#~1-C(Ph)=C=CH_2)]~+ at ambient temperature and the slower reacting cis isomer givign [trans-(PPh_3)(PMe_3)_2Pt(#eta#~1-C(Ph)=c=ch_2)]~+ AT 54 deg C. A ll new complexes were characterized by combination of elemental analysis, FAB mas spectrometry and IR and NMR (~1H, ~13C{~1H} and ~31P{~1H}) spectroscopy. The structure of [(PMe_3)_3Pt(#eta#~1-C(Ph)=c=ch+2)]BPh_4 centre dot 0.5 MeOH was determined by single-crystal X-ray diffraction analysis.