Synthesis and structure of novel triphenylarsine-substituted tungsten(0) Fischer carbene complexes

• Structure of cis triphenylarsine-substituted tungsten(0) Fischer-type carbenes.
• W–C bond trans AsPh3 < W–C bond trans carbene < W–C bond trans CO.
• Trans-influence for tetracarbonyl W(0)-carbenes: CO > PPh3 > AsPh3.

X-ray crystal structure determination, as well as IR and NMR spectroscopy of four novel triphenylarsine-substituted tetracarbonyl tungsten(0) Fischer carbene complexes of general formula [(CO)4(AsPh3)WC(OEt)(Ar)], with Ar = 2-thienyl (1), 2-furyl (2), 2-(N-methyl)pyrrolyl (3), 2,2′-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 W–C bond trans AsPh3 < W–C bond trans carbene < W–C 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 results.

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