STRUCTURES OF HEXACHLORONIOBATE(V) SALTS OF THE 1-METHYLIMIDAZOLE 1-METHYLIMIDAZOLIUM AND 2-METHYLIMIDAZOLIUM CATIONS

Both salts contain approximately octahedral [NbCl6]- anions with Nb-Cl bond lengths ranging from 2.326 (2) to 2.378 (2) angstrom. The 1-methylimidazole salt (I) contains the proton-bridged 1-methylimidazole/1-methylimidazolium cation, whereas the fully N-protonated 2-methylimidazolium ion is present in the 2-methylimidazole compound (II). Cohesion in the crystals is achieved by dipolar interactions between Cl atoms of [NbCl6]- and imidazole C-H groups for (I) and (II), as well as N-H ... Cl hydrogen bonds for (II).