Cyanido Antimonate(III) and Bismuthate(III) Anions.
The reaction of in situ generated E(CN)3 (E Sb, Bi) with different amounts of [Ph4P]CN and [PPN]CN [PPN] [Ph3P N PPh3] was studied, affording salts bearing the novel ions [E(CN)5]2 [Bi2(CN)11]5 and [Bi(CN)6]3 The valence lone pair of electrons on the central atom of antimony and bismuth(III) compounds can be either sterically active in an unsymmetric fashion (three shorter bonds x longer bonds) or symmetric (with rather long averaged bonds) In the presence of weakly coordinating cations (e.g. [Ph4P] and [PPN] the solid state structures of salts with [E(CN)5]2 anions contain well separated cations and monomeric anions, which display a sterically active lone pair and a monomeric square based pyramidal (pseudo octahedral) structure. The [Bi(CN)5*MeCN]2 acetonitrile adduct ion exhibits a strongly distorted octahedral structure, which is better understood as a [5 1] coordination. The intriguing [Ph4P]6[Bi2(CN)11]CN salt consists of separated cations and anions as well as well separated [Bi2(CN)11]5 and CN ions. The structure of the molecular [Bi2(CN)11]5 ion can be described as two square based pyramidal [Bi(CN)5]2 fragments connected by a disordered bridging CN ion, thereby leading to a distorted octahedral environment around the two Bi centers. Here the steric effect of the lone pair is much less pronounced but still present.
Inorganic chemistry