Lithioalkynyl Iron(II) or Ruthenium(II) Complexes as Precursors of Novel Alkynyl and Vinylidene Derivatives: Heterobimetallic Complexes containing a Bridging Ethynediyl System

Article abstract of DOI:10.1039/DT9950001901

Deprotonation of ethynyl complexes 5-C5H5)(dppm)> 1a (dppm = Ph2PCH2PPh2) and 5-C9H7)L2> with LiBu-t at -78 deg C gave the lithiated complexes 5-C5H5)(dppm)> 2a and 5-C9H7)L2> 2b-2d, respectively.These species have been used in situ as precursors of novel alkynyl and vinylidene complexes by reactions with electrophiles.Treatment of complexes 2a-2d with MeOSO2CF3 at -78 deg C gave vinylidene complexes 5-C5H5)(dppm)> 3a and 5-C9H7)L2> .Iodoalkynyl complexes 5-C9H7)L2> (L2 = 2PPh3 4b or dppe 4c) have been obtained by reaction of (py = pyridine) with 2b and 2c, respectively.Reaction of 2a-2d with SnPh3Cl yielded the ethynediyl bridging bimetallic complexes <(η⁵-C5H5)(dppm)Fe-CC-SnPh3> 5a and <(η⁵-C9H7)L2Ru-CC-SnPh3> .Similar heterobimetallic complexes <(η⁵-C5H5)(dppm)Fe-CC-Au(PPh3)> 6a and <(η⁵-C9H7)L2Ru-CC-Au(PPh3)> 6b-6d have been obtained by treatment of ethynyl complexes 1a-1d with and Tl(acac) (acac = acetylacetonate) in dichloromethane.Complexes 6a and 6b can alternatively be obtained by reaction of 5a and 5b with in the presence of .The crystal structure of 5a has been determined by X-ray diffraction methods.It shows a typical three-legged piano-stool geometry.The iron atom is bonded to the cyclopentadienyl ring, the two phosphorus atoms of a chelating dppm ligand, with a narrow bite angle <74.90(5) deg> and the terminal carbon of the triphenyltin acetylide group.The ethynyl bridge is bound to the iron and tin forming an CC-Sn angle of 162.8(4) deg and an almost linear Fe-CC arrangement <178.0(3) deg>.

Full text of DOI:10.1039/DT9950001901

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