Preparation and Characterization of Antimony and Arsenic Tricyanide and Their 2,2′‐Bipyridine Adducts

Abstract

The arsenic(III) and antimony(III) cyanides M(CN)3 (M=As, Sb) have been prepared in quantitative yields from the corresponding trifluorides through fluoride-cyanide exchange with Me3 SiCN in acetonitrile. When the reaction was carried out in the presence of one equivalent of 2,2'-bipyridine, the adducts [M(CN)3 ⋅(2,2'-bipy)] were obtained. The crystal structures of As(CN)3 , [As(CN)3 ⋅(2,2'-bipy)] and [Sb(CN)3 ⋅(2,2'-bipy)] were determined and are surprisingly different. As(CN)3 possesses a polymeric three-dimensional structure, [As(CN)3 ⋅(2,2'-bipy)] exhibits a two-dimensional sheet structure, and [Sb(CN)3 ⋅(2,2'-bipy)] has a chain structure, and none of the structures resembles those found for the corresponding arsenic and antimony triazides.

Preparation and Characterization of Group 13 Cyanides

“…In accordance with our previous reported synthesis of arsenic and antimony cyanides from the corresponding metal fluorides by fluoride–cyanide exchange with Me 3 SiCN, we attempted the synthesis of gallium, indium, and thallium tricyanide from the metal fluorides by fluoride–cyanide exchange with Me 3 SiCN in acetonitrile. However, only the unconverted starting materials could be recovered.…”

“…The preparation of cyanometallates commonly involves the reaction of simple metal salts such as chlorides or bromides with ionic cyanide salts such as KCN or [ n Bu 4 N]CN in aqueous solution . Recently, we reported the synthesis of the arsenic and antimony cyanides M(CN) 3 and their 2,2′‐bipyridine (bipy) adducts [(bipy)M(CN) 3 ] (M=As, Sb) by the reaction of the corresponding metal fluorides with trimethylsilyl cyanide . We have now extended this method to the synthesis of Group 13 cyanides.…”

On the Importance of σ–Hole Interactions in Crystal Structures

“…The three PnBs are symmetrically equivalent in the Sb(N 3 ) 3 compound and thus exhibit a worse directionality than the As(N 3 ) 3 compound (see Table 4 for distances and angles). In parallel to As(N 3 ) 3 , tricyano-arsenic(III) also undergoes three simultaneous PnBs, with three adjacent molecules in the crystal structure (USEPUF [100], see Figure 8a In the case of USEQAM [100] structure, the tricyano-antimony(III) is co-crystallized with 2,2 -bipyridine (Figure 9) and exhibits two very short PnBs between the N atoms of bipyridine and Sb (2.724 and 2.560 Å). The third PnB is significantly longer, and it involves the N atom of the cyano group of the adjacent molecule.…”

Arsenic‐Mediated C−C Coupling of Cyanides Leading to Cyanido Arsazolide [AsC4N4]−

“…[AsC 4 N 4 ] À salts with different counterions such as [PPh 4 ] + , [PPN] + = [Ph 3 P-N-PPh 3 ] + ,A g + ,a nd [BMIm] + are reported with [BMIm][AsC 4 N 4 ]b eing al ow-temperature ionic liquid (T m = À62 8C).Whereast he isolation and full characterization of all heavy pnictogen tricyanides, E(CN) 3 (E = PÀBi), [1][2][3][4][5][6][7][8] were reported,t ernary cyanidopnictate anionsh ave been known so far only for phosphorus, [9][10][11][12] antimony, [13] andb ismuth [13] but not for arsenic (Schemes 1a nd 2). The reactiono fA s(CN) 3 with cyanide salts resulted in the formation of an unknown cyanido arsazolide heterocycle, which represents as tructure isomer of the desired [As(CN) 4 ] À .T he structure, bonding, and formation of this unusual heterocycle is discussed featuring an arsenic mediated CÀCc oupling of cyanides.…”

“…Whereast he isolation and full characterization of all heavy pnictogen tricyanides, E(CN) 3 (E = PÀBi), [1][2][3][4][5][6][7][8] were reported,t ernary cyanidopnictate anionsh ave been known so far only for phosphorus, [9][10][11][12] antimony, [13] andb ismuth [13] but not for arsenic (Schemes 1a nd 2). Herein, we communicatet he unusual CÀ Cc oupling of cyanides mediated by arsenic upon the attempt-ed synthesis of cyanidoa rsenates of the type [As(CN) 3 + n ] nÀ (n = 1, 2, 3), yielding an unprecedented cyanidoa rsazolideh eterocycle (Scheme 3, Figure1right).…”