σ or π? Bonding interactions in a series of rhenium metallotetrylenes

Salt metathesis reactions between a low-valent rhenium(I) complex, Na[Re(eta(5)-Cp)(BDI)] (BDI = N,N'-bis (2,6-diisopropylphenyl)-3,5-dimethyl-beta-diketiminate), and a series of amidinate-supported tetrylenes of the form ECI[PhC((NBu)-Bu-t)(2)]) (E = Si, Ge, Sn) led to rhenium metallotetrylenes Re(E[PhC((NBu)-Bu-t)(2)])(eta(5)-Cp)(BDI) (E = Si (1a), Ge (2), Sn (4)) with varying extents of Re-E multiple bonding. Whereas the rhenium-stannylene 4 adopts a sigma-metallotetrylene arrangement featuring a Re E single bond, the rhenium-silylene (1a) and -germylene (2) both engage in pi-interactions to form short Re-E multiple bonds. Temperature was found to play a crucial role in reactions between Na(Re(eta(5)-Cp)(BDI)] and SiCl[PhC((NBu)-Bu-t)(2)], as manipulation of reaction conditions led to isolation of an unusual rhenium-silane, (BDI)Re(mu-eta(5).eta(1)-C5H4)(SiH[PhC((NBu)-Bu-t)(2)]) (1b) and a dinitrogen bridged rhenium-silylene, (eta(5)-Cp)(BDI)Re(mu-N-2)Si(PhC((NBu)-Bu-t)(2)] (1c), in addition to la. Finally, the reaction of Na(Re(eta(5)-Cp)(BDI)] with GeCl2 center dot dioxane led to a rare mu(2)-tetrelido complex, mu(2)-Ge(Re(eta(5)-Cp)(BDI)](2) (3). Bonding interactions within these complexes are discussed through the lens of various spectroscopic, structural, and computational investigations.

Automated summary

Salt metathesis reactions between a low-valent rhenium(I) complex and a series of amidinate-supported tetrylenes led to the formation of rhenium metallotetrylenes with varying extents of Re-E multiple bonding. Temperature played a crucial role in the reactions, leading to isolation of unusual products under different conditions, reflecting the complexity of these metal complexes. Bonding interactions within these complexes were discussed through various spectroscopic, structural, and computational investigations.