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

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 (t1/2 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; t1/2 >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.