The heavy pnictogen tricyanides, E(CN) (E=Sb, Bi), were synthesized from EF and Me SiCN in ionic liquids, for example, 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([BMIm][OTf]), which prevents the oligomerization of the molecular E(CN) species by formation of [BMIm][E(CN) (OTf)] salts in solution. Recrystallization of [BMIm][E(CN) (OTf)] from THF led to the isolation and full characterization of the molecular species E(CN) ⋅2 THF.

The reaction of in situ generated E(CN) (E = Sb, Bi) with different amounts of [PhP]CN and [PPN]CN ([PPN] = [PhP-N-PPh]) was studied, affording salts bearing the novel ions [E(CN)], [Bi(CN)], and [Bi(CN)]. 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., [PhP] and [PPN]), the solid-state structures of salts with [E(CN)] 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)·MeCN] acetonitrile adduct ion exhibits a strongly distorted octahedral structure, which is better understood as a [5 + 1] coordination. The intriguing [PhP][Bi(CN)]CN salt consists of separated cations and anions as well as well-separated [Bi(CN)] and CN ions. The structure of the molecular [Bi(CN)] ion can be described as two square-based-pyramidal [Bi(CN)] 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.

The chemistry of arsenic cyanides has been investigated and is found to be completely different to the chemistry of the heavier analogs antimony and bismuth as well as phosphorus. The reaction of As(CN) with cyanide salts resulted in the formation of an unknown cyanido arsazolide heterocycle, which represents a structure isomer of the desired [As(CN) ] . The structure, bonding, and formation of this unusual heterocycle is discussed featuring an arsenic mediated C-C coupling of cyanides. [AsC N ] salts with different counterions such as [PPh ] , [PPN] =[Ph P-N-PPh ] , Ag , and [BMIm] are reported with [BMIm][AsC N ] being a low-temperature ionic liquid (T =-62 °C).

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When [PPN]­SCN (1; PPN = [Ph3P–N–PPh3]) is treated with Me3Si–SCN in methanol, [PPN]­[H­(NCS)2] (2), a hydrogen diisothiocyanate salt bearing the [H­(NCS)2]− anion, was generated, isolated, and fully characterized. Pure heavy E­(NCS)3 [E = Sb (3), Bi (4)] species were obtained from the reaction of EF3 and an excess of Me3Si–SCN, while the tetrahydrofuran (THF) solvates E­(NCS)3·THF were isolated when the product was recrystallized from THF. When 2 equiv of 1 was combined with Me3Si–SCN and SbF3, [PPN]2[Sb­(NCS)5] (5) could be isolated. When 1 was added to BiF3, [PPN]2[Bi­(NCS)3(SCN)2·THF] (6·THF), containing three SCN– ions coordinating via the N atom and two coordinating via the S atom, was isolated after recrystallization from THF. The structures of 1, 2, 3·THF, 4·THF, 5, and 6·THF were determined. 3·THF displayed a typical [3 + 3] coordination mode with a trigonal-pyramidal environment in the first coordination sphere of the Sb3+ ion, and the dianion of 5, [Sb­(NCS)5]2–, featured a classical square-pyramidal molecular geometry around the Sb3+ ion with one additional Menshutkin-type interaction to one aryl ring of the [PPN]+ cation. 4·THF exhibited a distorted pentagonal-bipyramidal structure within a two-dimensional network, while in 6·THF, an octahedrally surrounded Bi3+ ion was observed.