Triamidoamine-supported zirconium complexes in the catalytic dehydrocoupling of 1,2-bisphosphinobenzene and -ethane

The readily prepared zirconium complex, [κ5-(Me3SiNCH2CH2)2NCH2CH2NSiMe2CH2]Zr (1), is an effective precatalyst in the dehydrocoupling of o-bisphosphinobenzene and 1,2-bisphosphinoethane to the known intercalated products. The phosphanido complex (N3N)Zr[κ2-1,2-PH(PH2)C6H4] (N3N=N(CH2CH2NSiMe3)33−), 2 was prepared independently by reaction of 1 with o-bisphosphinobenzene. Complex 2 was identified as an intermediate zirconium complex in the catalytic dehydrocoupling of o-bisphosphinobenzene. Likewise, previously reported (N3N)Zr(PHCH2CH2PH2) (3) was identified in the catalytic dehydrocoupling of 1,2-bisphosphinoethane. Investigation of the thermal decomposition of 2 and the reactivity of 2 with stoichiometric o-bisphosphinobenzene suggest that the catalysis proceeds via sequential PP bond forming steps. The solid state structure of 2, which features a six-coordinate (N3N)Zr-complex, is reported.

Graphical abstractTraimidoamine-supported zirconium complexes dehydrocoupling bisphosphine substrates, o-bisphosphinobenzene and 1,2-bisphosphinoethane, to intercalated products. An intermediate (N3N)Zr[κ2-1,2-PH(PH2)C6H4] (2) was identifies and independently prepared and structurally characterized. Thermal decomposition of 2 and the stoichiometric reactivity of 2 suggest that the catalysis proceeds via sequential P–P bond forming steps.Figure optionsDownload full-size imageDownload as PowerPoint slide