2,6-Diisopropylphenylimido and Diphenylacetylene Complexes of Tugsten containing the Bidentate Ligands 4,4'-Dimethyl-2,2'-bipyridine and 1,2-Bis(diphenylphosphino)ethane

Article abstract of DOI:10.1039/DT9950001147

Sodium-mercury amalgam reduction of <2> in the presence of 4,4'-dimethyl-2,2'-bipyridine (dmbipy) or 1,2-bis(diphenylphosphino)ethane (dppe) gave the d¹ complexes 1 and 2.A crystal-structure determination of complex 2 shows the three chloro ligands in a mer arrangement and the dppe ligand phosphorus atoms lying trans to one chloro ligand and also the imido ligand.The W-P bond trans to the chloro ligands is normal <2.550(2) Angstroem> whereas the W-P bond trans to the imido ligand is very long <2.765(2) Angstroem>.One phenyl group of dppe rotates to accommodate an isopropyl group of the imido ligand.Sodium-mercury amalgam reduction of <2> in the presence of dmbipy gave which the W-Cl stretches suggest is the mer trichloride.However, an IR spectrum of the product of standing <2> and dmbipy in tetrahydrofuran indicates the fac isomer.A reduction of <2> in the presence of dppe gave for which the mer isomer is preferred.The dppe complexes do not give characterisable complexes on further reduction in the presence of diphenylacetylene, ethylene or CO.Sodium-mercury amalgam reduction of 1 in the presence of diphenylacetylene gave which IR and NMR spectra indicate has an asymmetric structure where the alkyne ligand is a two-electron donor.Reductions of complex 1 under ethylene or CO gave and both of which consist of several isomers.

Full text of DOI:10.1039/DT9950001147

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