Reaction of the Tricyanoborate Dianion [B(CN)₃]^2–with HgCl₂

Abstract

The very reactive [B(CN)] dianion has a strongly nucleophilic boron atom and can be used for the synthesis of tricyanoborates, which otherwise are difficult to access. Herein the reaction of this anion with HgCl is reported. The main product is the anionic mercury complex [Hg(B(CN))]. Heteronuclear NMR spectroscopic experiments shows that the reaction proceeds via the intermediate [ClHgB(CN)]. Even though [Hg(B(CN))] is the main product, it is difficult to obtain it in pure form, because it slowly decomposes in the presence of water and air to [(NC)HgB(CN)]. All three anions were fully characterized by hetereonuclear NMR spectroscopy (B, C, andHg). Single-crystal X-ray diffraction studies of the salts K[ClHgB(CN)], [PhP][Hg(B(CN))], K[(NC)HgB(CN)], and [PhP][(NC)HgB(CN)] revealed linear coordination environments around mercury for all anions. The Hg-B bonds range from 2.219(5) Å in [Hg(B(CN))] to 2.148(11) Å in [ClHgB(CN)], are in accord with the sum of the covalent radii of mercury and boron, and can be described as covalent single bonds. A comparison with related complexes indicates that the [B(CN)] dianion is a stronger ligand than chloride, cyanide, or carbenes. [Hg(B(CN))] hydrolyses in solution only in the presence of oxygen. It is suggested that cis-[Hg(OH)(B(CN))] is formed as a very unstable intermediate, which decomposes very fast to [(NC)HgB(CN)] and other products. The anion cis-[Hg(OH)(B(CN))] would contain mercury in the unusual oxidation state +IV. Quantum-chemical calculations were performed to support this assumption.

Cyanohydridoborate Anions: Synthesis, Salts, and Low‐Viscosity Ionic Liquids

“…Furthermore, alkali metal salts of anion 2 provide an ideal entry via simple deprotonation to the unusual dianion B(CN) 3 2− (Scheme ) . This dianion reacts as a boron‐centered nucleophile and is therefore a versatile synthon for tricyanoborate anions [RB(CN) 3 ] − (e.g., R=alkyl, fluoroaryl, CO 2 H), [B 2 (CN) 6 ] 2− , and metal complexes . Herein, we report on different convenient syntheses of cyanohydridoborates in up to molar scales starting from readily accessible chemicals M [BH 4 ] ( M =Na (Na 5 ), K (K 5 )), BCl 3 , KCN, NaCN, and (CH 3 ) 3 SiCN.…”

“…[25,26] This dianion reacts as ab oron-centeredn ucleophile and is therefore av ersatile synthon for tricyanoborate anions[ RB(CN) 3 ] À (e.g.,R = alkyl, [21] fluoroaryl, [21,27] CO 2 H [25] ), [B 2 (CN) 6 ] 2À , [28] andm etal complexes. [29] Herein, we report on different convenient syntheseso fc yanohydridoborates in up to molar scales startingf rom readily accessible chemicals M[BH 4 ] (M = Na (Na5), K( K 5)), BCl 3 ,K CN,N aCN, and (CH 3 ) 3 SiCN. Furthermore, ad etailedo verview on physicochemical properties (meltingp oint, viscosity,c onductivity,e lectrochemical and thermals tability) of selected cyanohydridoborate-ILs is given.…”

Clustering of H2SO4 with BX3 (X = H, F, Cl, Br, CN, OH) compounds creates strong acids and superacids

“…Because of the wide application of boron compounds, considerable efforts have been devoted to synthesize these compounds and study their physical and chemical properties [13][14][15].…”

Analytic Energy Gradients and Hessians of Exact Two-Component Relativistic Methods: Efficient Implementation and Extensive Applications

“…The basis sets are cc-pVTZ-DK2 − for C, N, F, and Cl and x2c-TZVPPall for Hg. The optimized bond lengths and reaction energies (not corrected by zero-point energies) are collected in Table , to be compared with the previous results, , whereas the optimized Cartesian coordinates and vibrational frequencies are provided in Supporting Information.…”