New Types of CO-Releasing Molecules (CO-RMs), Based on Iron Dithiocarbamate Complexes and [Fe(CO)₃I(S₂COEt)]

Abstract

New CO-releasing molecules, [Fe(CO)3X(S2CNR2)] and [Fe(CO)3I(S2COEt)], are reported. [Fe(CO)3X(S2CNR2)] releases the first two carbonyls rapidly to myoglobin (t 1/2 < 1 min) and the third carbonyl more slowly. In the case of [Fe(CO)3I(S2COEt)], only 0.4 mol of CO are lost. [Fe(CO)3Br(S2CNEt2)] has low toxicity. CO loss is much slower from [Fe(CO)2(S2CNR2)2] (R2 = Me2, Et2, (CH2CH2)2O, (CH2CH2)2, (CH2CH2OH)2; t 1/2 >24 h) and is not observed from [Fe(CO)2(S2COEt)2]. The mechanism of CO loss was investigated using Gaussian 09 calculations for [Fe(CO)3Br(S2CNMe2)] and [Fe(CO)2(S2CNMe2)2]. The X-ray structures of [Fe(CO)3Br(S2CNMe2)] and [Fe(CO)3I(S2CNEt2)]2I2 were determined.

Carbon monoxide – physiology, detection and controlled release

“…This remaining metal fragment can either degrade to the metal ions and free coligands as observed for example for [(OC) 2 Fe(H 2 NCH 2 CH 2 PPh 2 ] 2+ (CORM-P1) 165 or attract another ligand to recomplete the coordination sphere as discussed for the dithiocarbamate (dtc) complexes [(OC) 4 Mn(dtc)] 166 and [(OC) 3 Fe(Br)(dtc)] binding HPO 4 2− , H 2 PO 4 − , halide or water at the free coordination site. 167 Further degradation steps may proceed via oxidative pathways. Thus, manganese(I)-based mononuclear CORMs were oxidized during step-wise CO release, finally yielding a dinuclear manganese(III) complex with a central Mn-O-Mn unit.…”

The chemistry, biology and design of photochemical CO releasing molecules and the efforts to detect CO for biological applications

“…Several general approaches to controlled CO release are being investigated. A number of compounds release CO thermally in solution [25][26][27]. Researchers in Germany have explored enzyme triggered CO release, making using of iron carbonyls, coordinated by an enol ligand, that thermally decomposed to release CO [28][29][30][31].…”

Live-Fibroblast IR Imaging of a Cytoprotective PhotoCORM Activated with Visible Light

“…To date the majority of CORMs are transition metal (TM) carbonyl complexes which under different stimuli are able to deliver CO to diseased or inflamed tissues in order to initiate and promote therapeutic effects at the site of disease. CO release in these molecules may be triggered by different strategies which include simple CO dissociation [4][5][6] , redox or ligand exchange mediated processes [7][8][9][10][11][12] , enzymatic triggering 13,14 or the use of electromagnetic radiation. [15][16][17] In general, at present, CORMs are not designed to target a specific receptor or intracellular target and their potential utility is credited to their fundamental ability to liberate CO.…”