X-ray crystal structure determination, as well as IR and NMR spectroscopy of four novel triphenylarsinesubstituted
tetracarbonyl tungsten(0) Fischer carbene complexes of general formula [(CO)4(AsPh3)
WC(OEt)(Ar)], with Ar ¼ 2-thienyl (1), 2-furyl (2), 2-(N-methyl)pyrrolyl (3), 2,20
-bithienyl (4), revealed a
cis-configuration for the substituted AsPh3 group relative to the carbene ligand for all four novel complexes.
All X-ray structures showed that the WeC bond trans AsPh3 < WeC bond trans carbene < WeC
bond trans CO. DFT calculations on all possible conformations of each complex due to the different
possible positions of the ligands and carbene substituents to each other, correlated with the experimental