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

New CO-releasing molecules, [Fe(CO)(3)X-(S2CNR2)] and [Fe(CO)(3)I(S2COEt)], are reported. [Fe-(CO)(3)X(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)(3)I(S2COEt)], only 0.4 mol of CO are lost. [Fe(CO)(3)Br(S2CNEt2)] has low toxicity. CO loss is much slower from [Fe(CO)(2)(S2CNR2)(2)] (R-2 = Me-2, Et-2, (CH2CH2)(2)O, (CH2C2H2)(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)(3)Br(S2CNMe2)] and [Fe(CO)(2)(S2CNMe2)(2)]. The X-ray structures of [Fe(CO)(3)Br(S2CNMe2)] and [Fe(CO)(3)I-(S2CNEt2)](2)I-2 were determined.