Coordination Chemistry of Diiodine and Implications for the Oxidation Capacity of the Synergistic Ag⁺/X₂ (X=Cl, Br, I) System

Abstract

The synergistic Ag+/X2 system (X=Cl, Br, I) is a very strong, but ill‐defined oxidant—more powerful than X2 or Ag+ alone. Intermediates for its action may include [Agm(X2)n]m+ complexes. Here, we report on an unexpectedly variable coordination chemistry of diiodine towards this direction: (A)Ag‐I2‐Ag(A), [Ag2(I2)4]2+(A−)2 and [Ag2(I2)6]2+(A−)2⋅(I2)x≈0.65 form by reaction of Ag(A) (A=Al(ORF)4; RF=C(CF3)3) with diiodine (single crystal/powder XRD, Raman spectra and quantum‐mechanical calculations). The molecular (A)Ag‐I2‐Ag(A) is ideally set up to act as a 2 e− oxidant with stoichiometric formation of 2 AgI and 2 A−. Preliminary reactivity tests proved this (A)Ag‐I2‐Ag(A) starting material to oxidize n‐C5H12, C3H8, CH2Cl2, P4 or S8 at room temperature. A rough estimate of its electron affinity places it amongst very strong oxidizers like MF6 (M=4d metals). This suggests that (A)Ag‐I2‐Ag(A) will serve as an easily in bulk accessible, well‐defined, and very potent oxidant with multiple applications.

Chasing the Mond Cation: Synthesis and Characterization of the Homoleptic Nickel Tetracarbonyl Cation and its Tricarbonyl‐Nitrosyl Analogue

“…[26,29] For the oxidation to the target cation we tested Ag + and NO + salts that may react innocent by formation of TMCCs, [23,26] but also non-innocent by formation of Ag-or NO-complexes. [20,30,31] Thus, the synergistic Ag + /0.5 I 2 system, [32,33] reported to be more suitable for the generation of novel TMCCs, [20] with a high redox potential of about 1.49 V vs. SHE in water was used. [33] Due to the high toxicity and volatility of neutral Ni(CO) 4 , we decided to use elemental nickel powder [34] as the starting material and converted it in CO atmosphere with the selected oxidizers to obtain the target cation [Ni(CO) 4 ]C + .…”

“…[20,30,31] Thus, the synergistic Ag + /0.5 I 2 system, [32,33] reported to be more suitable for the generation of novel TMCCs, [20] with a high redox potential of about 1.49 V vs. SHE in water was used. [33] Due to the high toxicity and volatility of neutral Ni(CO) 4 , we decided to use elemental nickel powder [34] as the starting material and converted it in CO atmosphere with the selected oxidizers to obtain the target cation [Ni(CO) 4 ]C + . Although, it appears that the reaction of the pure silver salt Ag[F{Al(OR F ) 3 } 2 ] with nickel metal in CO atmosphere is able to generate the target cation [Ni(CO) 4 ]C + , only a mixture of compounds that probably also includes the silver complex [Ag{Ni(CO) 4 } 2 ] + was obtained (see the Supporting Information, Section 4).…”

Chasing the Mond Cation: Synthesis and Characterization of the Homoleptic Nickel Tetracarbonyl Cation and its Tricarbonyl‐Nitrosyl Analogue

“…[26,29] For the oxidation to the target cation we tested Ag + and NO + salts that may react innocent by formation of TMCCs, [23,26] but also non-innocent by formation of Ag-or NO-complexes. [20,30,31] Thus, the synergistic Ag + /0.5 I 2 system, [32,33] reported to be more suitable for the generation of novel TMCCs, [20] with a high redox potential of about 1.49 V vs. SHE in water was used. [33] Due to the high toxicity and volatility of neutral Ni(CO) 4 , we decided to use elemental nickel powder [34] as the starting material and converted it in CO atmosphere with the selected oxidizers to obtain the target cation [Ni(CO) 4 ]C + .…”

“…[20,30,31] Thus, the synergistic Ag + /0.5 I 2 system, [32,33] reported to be more suitable for the generation of novel TMCCs, [20] with a high redox potential of about 1.49 V vs. SHE in water was used. [33] Due to the high toxicity and volatility of neutral Ni(CO) 4 , we decided to use elemental nickel powder [34] as the starting material and converted it in CO atmosphere with the selected oxidizers to obtain the target cation [Ni(CO) 4 ]C + . Although, it appears that the reaction of the pure silver salt Ag[F{Al(OR F ) 3 } 2 ] with nickel metal in CO atmosphere is able to generate the target cation [Ni(CO) 4 ]C + , only a mixture of compounds that probably also includes the silver complex [Ag{Ni(CO) 4 } 2 ] + was obtained (see the Supporting Information, Section 4).…”