New main-group ferrocenyldithiocarbamates and conversion to ferrocene oxazolidine-2-thione and -2-one

Three new main group ferrocenyldithiocarbamate complexes,  viz. , {Pb[(FcCH 2 )(CH 2 CH 2 OH)(NCS 2 )] 2 }·(FcCH 2 -3-oxazolidine-2-thione)·(H 2 O) (1), {Sb[(FcCH 2 )(CH 2 CH 2 OH)(NCS 2 )] 3 } (2) and {Bi[(FcCH 2 )(CH 2 CH 2 OH)(NCS 2 )] 3 } (3), (Fc = ferrocenyl) have been synthesized and characterized by elemental analyses and IR,  1 H and  13 C NMR spectroscopy as well as X-ray crystallography. The X-ray analysis of 1 indicates distorted trigonal bipyramidal geometry around Pb( II ) and a cyclised product, 3-ferrocenylmethyl-oxazolidine-2-thione (4), co-crystallizes with 1. The geometry around Sb( III ) in 2 is pseudo-octahedral, while 3 forms a dimer, displaying distorted square antiprism geometry around the Bi( III ) center. Several attempts to synthesize the pure cyclised product 3-ferrocenylmethyl-oxazolidine-2-thione (4) using Pb( II ) salts failed but 4 was fortuitously obtained in an attempt to synthesize the Cu( I ) cluster by the comproportionation of {Cu[(FcCH 2 )(CH 2 CH 2 OH)(NCS 2 )] 2 } using copper powder. Interestingly, varying the reaction time yielded another completely desulfurized cyclised product 3-ferrocenylmethyl-oxazolidine-2-one (5). Both 4 and 5 have been characterized using spectroscopic techniques and X-ray crystallography, and the possible mechanism for the conversion of {Cu[(FcCH 2 )(CH 2 CH 2 OH)(NCS 2 )] 2 } to 3-ferrocenylmethyl-oxazolidine-2-thione (4) has been explained with the help of periodic UV-Vis and ESI-MS experiments. This investigation will pave a new pathway for the synthesis of similar cyclised products using similar safe and sustainable reaction conditions.