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Anionic cyclometalated platinum(II) tetrazolato complexes as viable photoredox catalysts

Citation

Ranieri, AM and Burt, LK and Stagni, S and Zacchini, S and Skelton, BW and Ogden, MI and Bissember, AC and Massi, M, Anionic cyclometalated platinum(II) tetrazolato complexes as viable photoredox catalysts, Organometallics, 38, (5) pp. 1108-1117. ISSN 0276-7333 (2019) [Refereed Article]

Copyright Statement

Copyright 2019 American Chemical Society

DOI: doi:10.1021/acs.organomet.8b00913

Abstract

Variations in atmosphere oxygen and ocean sulfate concentrations through time are regarded as important controls on the cycles of sediment-hosted and volcanic-hosted ore deposits. However, estimates of atmosphere oxygen in the Proterozoic have been frustrated by the lack of a direct measurement method and conflicting evidence from various proposed geochemical proxies. Studies in the 1970s to 1990s suggested a relatively oxygenated atmosphere (> 3wt% O2) in the Proterozoic. However, since the late 1990s, new proxies and modelling have suggested very much lower levels of oxygen (< 0.02wt% O2). Focusing on redox-sensitive trace elements, here we combine a dataset of over 3000 LA-ICP-MS trace-element analyses on sedimentary pyrite, standardised against Berners Phanerozoic O2 modelling and direct measurement of oxygen concentrations in fluid inclusions in sedimentary halite, to develop the first detailed estimate for atmosphere O2 concentration and secular variation from 2200Ma to the present. The estimates suggest dynamic cycles of atmosphere oxygen that increased in frequency through time. There were possibly three first-order cycles in the Proterozoic varying from 400 to 600 million years in length and a further five first-order cycles in the Phanerozoic from 60 to 120 million years in length. Our estimates of oxygen concentration are at odds with most previous estimates. We suggest, rather than very low atmosphere oxygen in the Proterozoic, the mean concentration was about 7wt%, rising to a mean of about 10wt% in the Phanerozoic, but with significant cyclic variation of up to a maximum concentration of possibly over 30wt%. We observe that the proposed oxygen cycles correlate with biodiversity cycles and to the timing of major stratiform base-metal deposits in sedimentary basins. For example, minima in atmosphere oxygenation correlate with mass extinction events and stratiform ZnPbAg deposits, whereas maxima in oxygenation correlate with major evolutionary events, global periods of evaporite formation and the timing of stratiform copper deposits.

Item Details

Item Type:Refereed Article
Keywords:photoredox catalysis, platinum
Research Division:Chemical Sciences
Research Group:Inorganic Chemistry
Research Field:Transition Metal Chemistry
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Chemical Sciences
UTAS Author:Burt, LK (Mr Liam Burt)
UTAS Author:Bissember, AC (Dr Alex Bissember)
ID Code:131275
Year Published:2019
Web of Science® Times Cited:2
Deposited By:Chemistry
Deposited On:2019-03-12
Last Modified:2019-05-14
Downloads:0

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