Selective Enzymatic Oxidation of Silanes to Silanols

Compared to the biological world's rich chemistry for functionalizing carbon, enzymatic transformations of the heavier homologue silicon are rare. We report that a wild‐type cytochrome P450 monooxygenase (P450_(BM3) from Bacillus megaterium, CYP102A1) has promiscuous activity for oxidation of hydrosilanes to give silanols. Directed evolution was applied to enhance this non‐native activity and create a highly efficient catalyst for selective silane oxidation under mild conditions with oxygen as the terminal oxidant. The evolved enzyme leaves C−H bonds present in the silane substrates untouched, and this biotransformation does not lead to disiloxane formation, a common problem in silanol syntheses. Computational studies reveal that catalysis proceeds through hydrogen atom abstraction followed by radical rebound, as observed in the native C−H hydroxylation mechanism of the P450 enzyme. This enzymatic silane oxidation extends nature's impressive catalytic repertoire

Tin(IV) chalcogenide complexes:single source precursors for SnS, SnSe and SnTe nanoparticle synthesis

A family of tin(IV) bis(hexamethylsilylamide) complexes 2–9 have been synthesized by reaction of [Sn{N(SiMe3)2}2] (1) with the diphenyl dichalcogenanes Ph2E2 (E = S, Se, Te), the radical species TEMPO, or the group 16 elements to form the complexes [(PhE)2Sn{N(SiMe3)2}2] (2–4) and [(TEMPO)2Sn{N(SiMe3)2}2] (5), and [{(Me3Si)2N}2Sn(µ2-E)]2 (6–9) (E = S, 2 & 6; E = Se 3 & 7; E = Te, 4 & 9, E = O2, 9). The isolated tin complexes were characterized by elemental analysis, NMR spectroscopy, and the molecular structures of the complexes were determined by single crystal X-ray diffraction. Thermogravimetric analysis showed complexes 2–4 and 6–8 all to have residual masses close to those expected for the formation of the corresponding “SnE” systems. Complexes 2–4 and 6–8 were also assessed for their utility in the formation of nanoparticles. The materials obtained were characterized by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray analysis (EDX). Analysis showed formation of SnSe and SnTe from complexes 3–4 and 6–7, respectively