Unstable complexes of sandwich compounds and small molecules. 5. Complex formation of carbon dioxide molecules with organometallic compounds of transition elements at low temperatures

Metal-free synthesis of fully alternating polycarbonates from carbon dioxide (CO2) and epoxides is highly desired but a huge challenge. Here, we disclose the combination of tertiary amines with trialkyl boranes for completely alternating copolymerization of CO2 with epoxides. Triethylamine (TEA) pairing with triethyl borane (TEB), the simplest catalyst for the copolymerization of CO2 and propylene oxide (PO), afforded fully alternating poly(propylene carbonate) (PPC) with a turnover frequency (TOF) of 54 h-1 at 60 oC. Remarkably, diamine such as, N,N,N',N'-tetraethylethylenediamine (TEED) and triamine such as N,N,N',N'',N''-pentamethyldiethylene triamine (PMDETA) pairing with TEB exhibited improved the copolymer selectivity of up to 99%. Supplementally, the effect of trialkylborane structure on the copolymerization were also investigated. Moreover, PPCs prepared from these tertiary amines/ trialkyl boranes Lewis pairs showed the head-to-tail diad content of around 80%. The number-average molecular weight of PPC was up to 56.0 kg/mol with narrow distribution (Đ =1.16) and could be easily adjusted by simply varying the feeding ratios. The 1H NMR spectra and MALDI-TOF-MS spectra suggest that both tertiary amine-activating CO2 and TEB-masked end anions cooperatively promote the fully alternating CO2/epoxide copolymerization. This work provides an organocatalytic platform for well-defined CO2/epoxide copolymers using simple small molecules with high atomic utilization.<br>

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Inorganic metallocenes: The structures and aromaticity of sandwich compounds of the transition elements with inorganic rings

Coordination Chemistry Reviews ◽

10.1016/j.ccr.2011.04.011 ◽

2011 ◽

Vol 255 (23-24) ◽

pp. 2746-2763 ◽

Cited By ~ 30

Author(s):

Edward Maslowsky

Keyword(s):

Transition Elements ◽

Sandwich Compounds ◽

Inorganic Rings

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Reactions and structures of organometallic compounds of the transition elements

Principles of Organometallic Chemistry ◽

10.1007/978-94-010-9681-2_7 ◽

1968 ◽

pp. 183-214

Author(s):

G. E. Coates ◽

M. L. H. Green ◽

P. Powell ◽

K. Wade

Keyword(s):

Organometallic Compounds ◽

Transition Elements

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Computational UV Spectra for Amorphous Solids of Small Molecules

Physical Chemistry Chemical Physics ◽

10.1039/d1cp03255k ◽

2021 ◽

Author(s):

Austin Michael Wallace ◽

Ryan C. Fortenberry

Keyword(s):

Carbon Dioxide ◽

Interstellar Medium ◽

Small Molecules ◽

Gas Phase ◽

Amorphous Solids ◽

Uv Spectra ◽

Ammonia Water ◽

Gas Phase Molecules ◽

High Level

Ices in the interstellar medium largely exist as amorphous solids composed of small molecules including ammonia, water, and carbon dioxide. Describing gas-phase molecules can be readily accomplished with current high-level...

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