Cyanides and Isocyanides of Zinc, Cadmium and Mercury: Matrix Infrared Spectra and Electronic Structure Calculations for the Linear MNC, NCMCN, CNMNC, NCMMCN, and CNMMNC Molecules

Abstract

Cadmium atoms from laser ablation react with cyanogen, NC=CN, in excess argon during co‐deposition at 4 K, and even more on UV irradiation of the cold samples. Final annealing to 35 K increases bands at 2187.3 and 2089.2 cm−1 at the expense of weaker bands at 2194.6 and 2092.2 cm−1 through addition of another cadmium atom. Reaction products were identified by comparison with B3LYP and CCSD(T) computed frequencies and energies, through frequency differences between Zn and Cd products, and by cyanogen isotopic substitution. The CN radical, ZnNC, and CdNC were observed on sample deposition. Hg arc ultraviolet (UV) irradiation activates the insertion of Cd and Zn to form the NCCdCN, CNCdNC, NCZnCN and CNZnNC molecules. Next annealing increased the dimetal products NCCdCdCN, CNCdCdNC, NCZnZnCN, and CNZnZnNC at the expense of their single metal analogs. Laser ablated mercury amalgam also produced NCHgCN, NCHg−HgCN, CNHgNC and CNHg−HgNC. The Group12 metals form both cyanide and isocyanide products, and the argon matrix also traps the higher energy but much more intensely absorbing isocyanides. In the isocyanide case bond polarity results in very intense infrared absorptions. Group 12 metals produce shorter M−M bonds in the dimetal cyanides NCM−MCN and isocyanides CNM−MNC than in the M−M itself, and their computed M−M bond lengths compare favorably with those measured for dimetal complexes stabilized by large ring containing molecular ligands.

Cyanides, Isocyanides, and Hydrides of Zn, Cd and Hg from Metal Atom and HCN Reactions: Matrix Infrared Spectra and Electronic Structure Calculations

“…[ 9 , 17 ] Infrared (IR) spectra were recorded at 0.5 cm −1 resolution on a FTIR vacuum spectrometer (Bruker Vertex 70v) equipped with a transfer optic and Mid‐IR MCT detector (4000–450 cm −1 ). Matrix samples were annealed at different temperatures and cooled back to 5 K, and selected samples were irradiated in the ultraviolet (UV) by a medium pressure mercury arc street lamp (175 W):[ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ] Observed and calculated vibrational frequencies are reported here in cm −1 units.…”

“…The ZnNC isomer could also be produced by UV irradiation of Zn atoms and (CN) 2 co‐deposited in solid argon [18] . The N−C stretch for the analogous CdNC molecule was observed at 2069.7 cm −1 in experiments reacting Cd and (CN) 2 , [20] and the analogous higher energy HgNC molecule is produced here from HCN and Hg ablated from a dental amalgam target [9] . This novel use of a dental amalgam ablation target adds more to the known chemistry for mercury.…”

“…For investigation of novel cyanide and isocyanide molecules with infrared (IR) spectroscopy, we have produced by laser ablation Group 2, 3, 4, 7, 8 and 13 metal atoms as well as the Ce, Nd, Th, and U atoms. We have observed their reactions with cyanogen and U with hydrogen cyanide, and Zn with oxygen and hydrogen mixtures [1–20] …”

“…We have observed their reactions with cyanogen and U with hydrogen cyanide, and Zn with oxygen and hydrogen mixtures. [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ]…”

“…Here follows the complementary investigation of Zn, Cd and Hg atom reactions with HCN, which are more productive than the reactions with NCCN studied earlier. [ 18 , 20 ] Additional information was obtained with the H 13 CN reagent and the resulting isotopic shifts and isotopic frequency ratios became useful diagnostics. Our goal using the matrix isolation technique was to produce the zinc, cadmium, and mercury cyanides MCN and isocyanides MNC in these metal atom reactions with HCN, and to measure their argon matrix infrared spectra.…”