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Despite the title of the publication, Fletcher et al. both present an IR spectrum of diiron nonacarbonyl in a matrix of ($\ce{Ar}$ + 10% $\ce{CO}$, recorded at $\pu{15 K}$) in the $\nu(\ce{C-O})$ region of about $2080 \dots \pu{1820 cm^-1}$ (left to right hand side) as below:
(composite of two illustrations by Fletcher et al.)
Given the data recorded, the ...
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It basically comes down to molecular symmetry and since Buttonwood provided an answer just seconds ago, I'll leave the following as visualisations for it.
An optimisation of $\ce{Fe2(CO)9}$ at the DF-B97D3/def2-SVP level of theory results in a D3h symmetric molecule.
This in term results in degenerate vibrations (E') for the bridging $\ce{CO}$ at $\pu{1922 ...
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The answer is a definitive affirmative yes.
You don't need to reach out for proteins, organic dyes are known to suffer from solvatochromism in function of the polarity of the solvent they are dissolved. It either may be a bathochromic shift (or, red shift) of the UV-Vis absorption recorded, or a hypsochromic shift (or blue shift). In large proteins, you ...
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From my answer:
The IUPAC goldbook states that:
"pyro" is used as a prefix designating compounds formed by heating a compound, usually with the elimination of water, carbon dioxide, or other simple molecule, e.g. pyroglutamic acid from glutamic acid.
Since Pyroboric acid is made by heating boric acid, it is prefixed as pyro. You can also call it ...
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The short answer is that we'd like to do the first, but solving the multi-electron Schrodinger equation is impossible, so we use variations of your second option (ie considering many separate one-electron wavefunctions) to get something that matches experimental data as closely as possible, even though we don't ever get an explicit form of the true multi-...
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