956972-12-6Relevant articles and documents
Time-Resolved Ultraviolet-Infrared Experiments Suggest Fe-Cu Dinuclear Arene Borylation Catalyst Can Be Photoactivated
Davis, Jacob T.,Martinez, Erin E.,Clark, Kyle J.,Kwon, Doo-Hyun,Talley, Michael R.,Michaelis, David J.,Ess, Daniel H.,Asplund, Matthew C.
, p. 1859 - 1865 (2021)
Heterodinuclear complexes with a direct metal-metal bond offer the possibility of unique mechanisms and intermediates. The Cp(CO)2Fe-Cu(IPr) (IPr = N,N-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) heterodinuclear complex 1 was reported to photochemically catalyze arene borylation. To examine possible initial steps of photoinitiated catalysis, we synthesized a triethylsilyl-substituted Fe-Cu catalyst derivative 5 that provided cyclohexane solubility to conduct time-resolved UV-IR studies. Time-resolved vibrational spectroscopic measurements suggest that photolysis of 5 stimulates CO dissociation without Fe-Cu metal-metal bond cleavage. UV-IR measurements of 5 with added pinacolborane (HBPin) showed a very similar set of IR bleaches and a new monocarbonyl IR absorbance, and HBPin appears to stabilize the monocarbonyl species. This suggests that arene borylation catalysis may begin with a photochemical step rather than a relatively endothermic thermal-induced cleavage of the Fe-Cu bond, and therefore a new possible catalytic cycle is proposed.
Insight into the Decomposition Mechanism of Donor-Acceptor Complexes of EH2(E = Ge and Sn) and Access to Germanium Thin Films from Solution
Brown, Alex,Dai, Guoliang,Ferguson, Michael J.,Mcdonald, Robert,Rivard, Eric,Sinclair, Jocelyn
supporting information, (2020/08/12)
Electron-donating N-heterocyclic carbenes (Lewis bases, LB) and electron-accepting Lewis acids (LA) have been used in tandem to yield donor-acceptor complexes of inorganic tetrelenes LB·EH2·LA (E = Si, Ge, and Sn). Herein, we introduce the new germanium (II) dihydride adducts ImMe2·GeH2·BH3 (ImMe2 = (HCNMe)2C:) and ImiPr2Me2·GeH2·BH3 (ImiPr2Me2 = (MeCNiPr)2C:), with the former complex containing nearly 40 wt % germanium. The thermal release of bulk germanium from ImMe2·GeH2·BH3 (and its deuterated isotopologue ImMe2·GeD2·BD3) was examined in solution, and a combined kinetic and computational investigation was undertaken to probe the mechanism by which Ge is liberated. Moreover, the thermolysis of ImMe2·GeH2·BH3 in solution cleanly affords conformal nanodimensional layers of germanium as thin films of variable thicknesses (20-70 nm) on silicon wafers. We also conducted a computational investigation into potential decomposition pathways for the germanium(II)- and tin(II)-dihydride complexes NHC·EH2·BH3 (NHC = [(HCNR)2C:]; R = 2,6-iPr2C6H3 (Dipp), Me, and H; and E = Ge and Sn). Overall, this study introduces a mild and convenient solution-only protocol for the deposition of thin films of Ge, a widely used semiconductor in materials research and industry.
Donor-acceptor complexation and dehydrogenation chemistry of aminoboranes
Malcolm, Adam C.,Sabourin, Kyle J.,McDonald, Robert,Ferguson, Michael J.,Rivard, Eric
, p. 12905 - 12916 (2013/02/22)
A series of formal donor-acceptor adducts of aminoborane (H 2BNH2) and its N-substituted analogues (H 2BNRR′) were prepared: LB-H2BNRR′2- BH3 (LB = DMAP, IPr, IPrCH2 and PCy3; R and R′ = H, Me or tBu; IPr = [(HCNDipp)2C:] and Dipp = 2,6-iPr 2C6H3). To potentially access complexes of molecular boron nitride, LB-BN-LA (LA = Lewis acid), preliminary dehydrogenation chemistry involving the parent aminoborane adducts LB-H2BNH 2-BH3 was investigated using [Rh(COD)Cl]2, CuBr, and NiBr2 as dehydrogenation catalysts. In place of isolating the intended dehydrogenated BN donor-acceptor complexes, the formation of borazine was noted as a major product. Attempts to prepare the fluoroarylborane-capped aminoborane complexes, LB-H2BNH 2-B(C6F5)3, are also described.
