Synthesis and coordination properties of new σ(2),λ(3)-P/N switchable chelators based on [1,2,3]-diazaphosphole
Abstrakt
Novel hybrid ligands based on [1,2,3]-diazaphosphole (dap) were prepared and their coordination behaviour toward selected transition metals has been studied. The syntheses and spectroscopic properties of polydentate bis(5-t-butyl-[1,2,3]-diazaphosphol-2-yl)-dimethylsilane (Bdaps(H,tBu)) and bis(4-methyl-5-ethyl-[1,2,3]-diazaphosphol-2-yl)-dimethylsilane (Bdaps(Me,Et)) are reported.
In zerovalent compounds of the type [M(CO)(4)(κ(2)-P,P'-Bdaps(R1,R2))] (R1 = Me, R2 = Et, M = Cr, Mo and W; R1 = H, R2 = t-Bu, M = W) and [Ni(κ(2)-P,P'-Bdaps(H,tBu))(2)] the ligand serves as a P,P'-donor, giving rigid six-membered chelate rings. Bdaps(Me,Et) is also capable of behaving as an N,N'-chelator as confirmed by isolation of high-spin chelate complex [CoBr2(κ(2)-N,N'-Bdaps(Me,Et))].
The reaction of parent 2H-4-methyl-5-ethyl-[1,2,3]-diazaphosphole with NiBr(2).DME yielded paramagnetic compound [NiBr2(κ-N-dap)(2)], where the dap heterocycle bonds with the nickel(ii) centre via a 1-nitrogen donor atom in a distorted tetrahedral environment. All the studied complexes showing different coordination modes of the new ligands were fully characterized, including single-crystal X-ray diffraction analysis.