| Abstract: | Reaction of the Grignard reagent with polydentate nitrogen‐donor ligands yields new species with rare magnesium coordination and possible catalytic activity. In the first of the title compounds, poly[[μ4‐dihydrobis(pyrazol‐1‐yl)borato‐κ2N,N′]potassium(I)], [K(C6H8BN4)]n, (I), polymeric chains form a two‐dimensional network in the [100] plane. Each potassium ion is coordinated by four N atoms of pyrazolyl ligands, while weak (μ‐BH)...K+ interactions additionally stabilize the structure. The K and B atoms both lie on a mirror plane. In three new structures obtained by disproportionation of the Grignard reagent, each Mg atom is bound to a κ2N,N′‐type ligand, forming the basal plane, and tetrahydrofuran molecules occupy the axial positions. Di‐μ‐chlorido‐bis[dihydridobis(pyrazol‐1‐yl)borato]tris(tetrahydrofuran)dimagnesium(II), [Mg2(C6H8BN4)2Cl2(C4H8O)3], (II), adopts a dimeric structure with μ‐Cl—Mg interactions. One of the Mg atoms has an octahedral coordination, while the other has a distorted square‐pyramidal environment. However, in the bis‐chelate compounds bis[dihydridobis(pyrazol‐1‐yl)borato‐κ2N,N′](tetrahydrofuran‐κO)magnesium(II), [Mg(C6H8BN4)2(C4H8O)], (III), and bis[dihydridobis(pyrazol‐1‐yl)borato‐κ2N,N′]bis(tetrahydrofuran‐κO)magnesium(II), [Mg(C6H8BN4)2(C4H8O)2], (IV), the Mg atoms have square‐pyramidal and octahedral environments, respectively. The Mg atom in (IV) lies on an inversion centre. |
