Questions tagged [carbonyl-complexes]

Complexes or (coordination) compounds involving carbon monoxide as a ligand. For compounds of the carbonyl group use carbonyl-compounds instead.

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CO-vibration in metal carbonyl

I'm struggling to understand the trend of $\ce{CO}$-vibration in isoelectronic metal carbonyls. $$ \begin{array}{lr|lr} \hline \text{Compound} & ν/\pu{cm-1} & \text{Compound} & ν/\pu{cm-1}...
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1answer
626 views

What is the oxidation state of Mn in HMn(CO)5?

What is the oxidation state of $\ce{Mn}$ in $\ce{HMn(CO)5}$? If $\ce{H}$ has an oxidation state of $+1$, then $\ce{Mn}$ should have oxidation state of $-1$, which I'm not sure is possible. On the ...
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Why are palladium and platinum carbonyls unstable at room temperature?

By palladium and platinum carbonyls, I mean the mononuclear, homoleptic, charge-neutral, binary carbonyl complexes of the form $\ce{M(CO)_n}$ and not any heteroleptic complexes like $\ce{Pd(CO)(PPh3)3}...
6
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1answer
256 views

Why does the 31P{1H} NMR spectrum of cis-[Mo(CO)2(dppe)2] show two signals?

I've tried searching for literature references that explain this, finding only a single reference which refers to the two signals as originating from phosphine environments cis/trans to carbonyls, ...
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1answer
258 views

Why is carbon monoxide a monodentate ligand

Carbon monoxide has lone pairs on both the carbon and the oxygen atoms. However, I have never seen any complex where the oxygen atom or both the oxygen and the carbon atoms are the donors. I know ...
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1answer
604 views

Why is the oxidation state of Co -1 in [Co(CO)4]-?

In $\ce{[Co2(CO)8]}$, most people say the charge of $\ce{Co}$ is 0. How does it become $\ce{[Co(CO)4]-}$? Most answers would say that $\ce{Co}$'s charge becomes -1. How does this work? -1 is not ...
2
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1answer
2k views

Reaction of anisole and succinic anhydride in presence of aluminium chloride

Predict the structures of the intermediates/products in the following reaction sequence: In the first step, I know that aluminium chloride is playing some role, as otherwise hydronium ion ...
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42 views

Why is this scintillator component turning into a milky-white emulsion?

I am a chemistry and physics double major doing some chemistry work in a nuclear physics lab. My mentor is a physicist, so his area of expertise is occasionally mismatched with what I need for my ...
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2answers
1k views

Is there an iron–iron bond in diiron nonacarbonyl?

Diiron nonacarbonyl, $\ce{[Fe2(CO)9]}$, is often depicted with an Fe–Fe bond as shown at the left-hand side: The Fe—Fe bond is usually invoked in order to (1) explain the observed diamagnetism and (2)...
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178 views

Magnetic anisotropy of triple bonds

Is the rule for shielding/deshielding areas in NMR bond dependent? The acetylene C triple bond C has deshielding zone perpendicular to the triple bond. Will the same deshielding zone hold true for C ...
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408 views

C-O bond strength in metal carbonyls [duplicate]

The metal carbonyls (and similar organometallic compounds) involve a combination of a $\sigma$-bond, a $\pi$-bond and backbonding. The bond strengths under consideration are the metal-carbon bond and ...
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3answers
7k views

Can Fe(CO)5 adopt both square pyramidal and trigonal bipyramidal geometries?

I know the hybridization of $\ce{Fe(CO)5}$ is $\mathrm{dsp^3}$. According to my book, coordination compounds with coordination number 5 can interchange between square pyramidal and trigonal ...
4
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1answer
357 views

Semi-sandwich complex IUPAC name

I've tried looking here, but I can't figure it out. As a start, what is just the cobalt and cyclopentadienyl anion compound called. How does that name get added to the trimethylphosphine and carbonyl ...
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2answers
511 views

Why do the protons in pentacarbonylmethylmanganese show up at –0.21 ppm?

The $\ce{^1H}$ NMR of $\ce{Mn(CO)5CH3}$ shows a resonance at –0.21 ppm, which has to be due to the methyl group. Why are the protons so shielded? I would have thought that all the pi backdonation ...
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124 views

Effects on Stretching Frequencies in Organometallic Complexes

If you added a negative charge to $\ce{Mo(CO)_6}$ how would this effect the $\ce{CO}$ stretching frequency in an IR spectrum? My thoughts are that it would lower the $\ce{CO}$ stretching frequency ...
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399 views

Comparing IR stretching bands in molybdenum complexes

Why would the infrared stretching frequency of $\ce{CO}$ (which is about $2140~\mathrm{cm^{-1}}$ in gaseous form) be $1982~\mathrm{cm^{-1}}$ in $\ce{[Mo(CO)_6]}$ and even lower in $\ce{[Mo(CO)3(η^6$\...
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562 views

Why is MP2 failing to calculate proper IR frequencies for [Co(CO)4]- and [Fe(CO)4]2-?

I was doing some IR calculations on different 3d transition metal carbonyl complexes during some practical courses where we were introduced to effective core potentials. While doing this we found that ...
6
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1answer
145 views

Structure of Niobium and Tantalum carbonyls

$\ce{V(CO)6}$ is well known to be an unusual 17 valence electron, paramagnetic octahedral complex. Do the corresponding tantalum and niobium species form simple dimers or more complicated structures ...
2
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1answer
236 views

Fehling's Test meaning for partial formation of a precipitate?

Whilst doing tests on two unknown solutions, I used Fehling's test. The solutions could be a mixture of compounds or just one compound dissolved in water/ another solvent - I don't know. Upon adding ...
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1answer
2k views

Why does Fe(CO)₄ adopt a tetrahedral, as opposed to square planar, geometry?

Why does $\ce{Fe(CO)4}$ adopt a tetrahedral, as opposed to square planar, geometry? Here's my analysis: Factors for square planar: coordination: 4 $\ce{Fe(0)}$: d8 $\ce{CO}$: strong field ligand (...
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1answer
910 views

Relativistic effect: d-electrons in metallorganic complexes

With higher period the d-electrons of the metal are less strong bonded and therefore oxidative addition is easier for $\ce{Ir(I)}$ than for $\ce{Rh(I)}$ and much easier than for $\ce{Co(I)}$. For ...
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1answer
141 views

Carbonyl/Nitrosonium Complex Stability

Why is the nickel complex exhibiting the strongest pi-bonding? From what I understand, charge density plays a role. Also we need some empty orbitals on the metal cation, since we're looking at Lewis ...
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1answer
111 views

Photochemical ligand substitution of metal carbonyls - role of water cooled lamp-jacket?

Why, in the photochemical substitution of a ligand in a carbonyl complex, is a water-cooled lamp jacket required to separate the solution and the mercury vapour lamp? It's shown in Figure 22.16 of ...