Weakly Coordinating Anions:  Crystallographic and NQR Studies of Halogen−Metal Bonding in Silver, Thallium, Sodium, and Potassium Halomethanesulfonates

Abstract

35Cl, (79,81)Br, and (127)I NQR (nuclear quadrupole resonance) spectroscopy in conjunction with X-ray crystallography is potentially one of the best ways of characterizing secondary bonding of metal cations such as Ag(+) to halogen donor atoms on the surfaces of very weakly coordinating anions. We have determined the X-ray crystal structure of Ag(O(3)SCH(2)Cl) (a = 13.241(3) A; b = 7.544(2) A; c = 4.925(2) A; orthorhombic; space group Pnma; Z = 4) and compared it with the known structure of Ag(O(3)SCH(2)Br) (Charbonnier, F.; Faure, R.; Loiseleur, H. Acta Crystallogr., Sect. B 1978, 34, 3598-3601). The halogen atom in each is apical (three-coordinate), being weakly coordinated to two silver ions. (127)I NQR studies on Ag(O(3)SCH(2)I) show the expected NQR consequences of three-coordination of iodine: substantially reduced NQR frequencies nu(1) and nu(2) and a fairly small NQR asymmetry parameter eta. The reduction of the halogen NQR frequency of the coordinating halogen atom in Ag(O(3)SCH(2)X) becomes more substantial in the series X = Cl < Br < I, indicating that the coordination to Ag(+) strengthens in this series, as expected from hard-soft acid-base principles. The numbers of electrons donated by the organic iodine atom to Ag(+) have been estimated; these indicate that the bonding to the cation is weak but not insignificant. We have not found any evidence for the bonding of these organohalogen atoms to another soft-acid metal ion, thallium. A scheme for recycling of thallium halide wastes is included.

Coordinating Ability of Anions, Solvents, Amino Acids, and Gases towards Alkaline and Alkaline‐Earth Elements, Transition Metals, and Lanthanides

“…The search for weakly coordinating anions has been av ery active area of research in recent years, [1][2][3][4][5][6][7][8][9][10][11] The most recent attempt led to the design of af amily of anionsb ased on an imidazolyl-phenyl platform,w hose solubilities and coordinating abilitiesm ay be controlled by attachingavariety of substituents. [12] The goal is to have the possibility of using them as counterions with cationic metal complexes,w ithout them interferingw ith the coordination of other Lewis bases present in the reaction media.…”

Construction of a series of inorganic–organic hybrid coordination polymers based on hexamethylenetetramine and sulfonate ligands

“…Sulfonates were a relatively less well investigated class of ligands in comparison with carboxylates and phosphonates because it is a poor ligand that are incapable of forming stable coordination bonds with transition metal ions [8][9][10][11][12][13]. However, silver(I) sulfonates are exception owing to the soft Lewis acidic properties of silver(I) ion and its flexible coordinative tendency to the sulfonate anions [14][15][16][17][18][19][20][21][22][23][24]. Until now, silver sulfonates incorporating secondary ligands have attracted increasing interest.…”

35Cl NQR spectra of group 1 and silver dichloromethanesulfonates

“…Silver (I) monochloromethanesulfonate, Ag + (ClCH 2 SO − 3 ), was a b Fig. 1 a Dichloromethanesulfonate ion (at left); b dichloromethanesulfonyl chloride synthesized earlier and was shown by X-ray crystallography and 35 Cl NQR (nuclear quadrupole resonance) spectroscopy to have Ag-Cl coordination (organochlorine coordination to Ag + produces a relatively large shift of 35 Cl NQR frequencies to lower values) [2]. Silver (I) trichloromethanesulfonate Ag + (Cl 3 CSO − 3 ) [3] was also synthesized; NQR indicated that it did not have such coordination [3].…”

“…Wulfsberg et al [2] prepared monochloromethanesulfonates by the reaction of chloromethanesulfonyl chloride, ClCH 2 SO 2 Cl, with group I metal carbonates in methanol.…”