Diverse Post-Metathesis Reactivities of Mixed Amido-Isothiocyanato Molybdenum Complexes

Attempts to prepare mixed isothiocyanato–bis(imido)
MoVI complexes led to the discovery of post-metathesis
rearrangements
toward three distinct products (1–3), which feature the NCS-derived chelators [N(NMe2)CS]2– (L1 in dinuclear 1 and 2) and [N(SiMe3)(NMe2)CS]− (L2 in
mononuclear 3). Notably, the preparation of bidentate
ligand L1 and its coordination
chemistry are unprecedented. Together with computational studies,
it is proposed that the putative “mono-substituted”
intermediate [Mo(NtBu)2(NMe2)(NCS)] serves as the common starting point for the observed
molecular transformations. Construction of the [Mo(NtBu)2(NCS)2] core was ultimately possible
in the presence of additional stabilizing donors (THF or PMe3), which yielded the complexes [Mo(NtBu)2(NCS)2(THF)2] (4) and [Mo(NtBu)2(NCS)2(PMe3)2] (5).