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(S 2 CNR 2 )] and [Fe(CO) 3 I(S 2 COEt)], are reported. [Fe(CO) 3 X(S 2 CNR 2 )] 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(S 2 COEt)], only 0.4 mol of CO are lost. [Fe(CO) 3 Br(S 2 CNEt 2 )] has low toxicity. CO loss is much slower from [Fe(CO) 2 (S 2 CNR 2 ) 2 ] (R 2 = Me 2, Et 2, (CH 2 CH 2 ) 2 O, (CH 2 CH 2 ) 2, (CH 2 CH 2 OH) 2; t 1/2 >24 h) and is not observed from [Fe(CO) 2 (S 2 COEt) 2 ]. The mechanism of CO loss was investigated using Gaussian 09 calculations for [Fe(CO) 3 Br(S 2 CNMe 2 )] and [Fe(CO) 2 (S 2 CNMe 2 ) 2 ]. The X-ray structures of [Fe(CO) 3 Br(S 2 CNMe 2 )] and [Fe(CO) 3 I(S 2 CNEt 2 )] 2 I 2 were determined.