NH-functionalized tungsten complexes of 2-(dimethylphosphino)imidazole

Ligand substitution in W(CO)4(NO)(ClAlCl3) with 2-(dimethylphosphino)imidazole (dmpi) bearing an acidic NH functionality afforded W(Cl)(CO)(NO)(bdmpi)(dmpi) (1) (bdmpi = 1,2-bis(dimethyl-phosphino)imidazole), while the reaction of dmpi with W(Cl)(NO)(P(OMe)3)4 led to the isolation of W(Cl)(NO)(dmpi)4 (2) together with W(Cl)(NO)(bdmpi)(dmpi)2 (3). Attempts to replace the chloride by a hydride ligand in 1–3 applying various hydride reagents did not lead to stable products. The soluble compound W(Cl)(NO)(dmpe)(dmpi)2 (5) was prepared by an alternative route from W(Cl)(NO)[P(OMe)3)]4 via the intermediacy of W(Cl)(NO)(P(OMe)3)2(dmpe) (4). The protection of the NH function in 5 was approached applying BuLi and subsequently Me3SiCl to afford [W(Cl)(NO)(dmpe)(tmsdmpi)2] (tmsdmpi = 1-trimethylsilyl-2-dimethylphosphino-imidazole) (6) which could not be isolated in pure form. The reaction of 5 with NaHBEt3 led to the formation of a deprotonated and nitrogen-coordinated salt Na[W(NO)(dmpe)(dmpi)(tebdmpi)] (7) (tebdmpi = 2-dimethylphosphino-3-triethylboro-imidazole). Compound 7 crystallized from CH3CN to establish a one-dimensional chain structure in the solid state. The structures of compounds 1–5 and 7 were studied by single-crystal X-ray diffraction.

Graphical abstractA new type of NH-functionalized ligand 2-(dimethylphosphino)imidazole (dmpi) was prepared and probed to synthetically access tungsten complexes.Figure optionsDownload full-size imageDownload as PowerPoint slide