Questions tagged [coordination-compounds]

This tag is for questions concerning coordination compounds including but not limited to ligand properties, metal properties, orbital splitting, micro- and macroscopic properties of entire complexes etc. For complexes where carbon monoxide is the only ligand, use the [carbonyl-complexes] tag instead. For organic catalysts or proteins, the tag is applicable if the question is about the metal’s direct coordination sphere.

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Ferrocene's band gap is supposed to make it colorless but it isn't. Why is it so?

Wang and Islam [1] state that the ferrocene molecule's band gap, i.e. the HOMO-LUMO gap at the Kohn-Sham level, is 5.03 eV, which corresponds to an absorption wavelength of at most 240 nm. So, ...
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Crystal Field Splitting in Octahedral Complex

So i was going through my 1st year engineering chemistry textbook as a i have test in about a few weeks. So my textbooks says: "Repulsion by six ligands in an octahedral complex splits the d ...
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Well I know ions have same bond order but does it also mean there bond length is same too? [closed]

This is question regarding that if bond order is same then is it necessary to have bond lengths same and if not what is true order of bond lengths
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Are carboxylic anhydrides in graphene oxides considered adsorption sites for metals? If so, are they more or less reactive than carboxylic acids?

The literature abundantly addresses the fact that carboxylic acids present in graphene oxides act as efficient adsorption sites for metals in aqueous solutions (e.g., HE et al., 2021; ZHAO et al., ...
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What kind of Spinel Structure is $Co^{2+}Fe^{3+}O_4$ [closed]

It's asked to me to calculate the magnetic moment of $Co^{2+}Fe^{3+}O_4$. My question is what kind of structure it is containing only one Fe. And does Fe takes tetrahedral site or octahedral site? ...
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Are nitro and nitrito-N interchangeable in the IUPAC name of a complex?

I searched but couldn't find anywhere whether nitro and nitrito-N can both be used in the IUPAC name of an inorganic complex. For example, triamminetrinitrocobalt(III) and triamminetrinitrito-N-cobalt(...
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Can denticity and hapticity be defined simulaneously for a ligand?

I am freshly studying coordination chemistry. What I understand from denticity and hapticity is: Denticity - no. of electron donating sites in a ligand. Hapticity - no. of electron donating atoms in a ...
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2 votes
1 answer
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In acids why does polarising the O-H bond weaken rather than strengthen it?

In hexaaquaions it is generally true that aqueous solutions of complex ions with a higher positive charge on the central metal ion will have a lower pH. Explanations typically note that the greater ...
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Colour of diamagnetic compounds using Crystal Field Theory

I know that the colour in coordination compounds can be explained by CFT in terms of d-d transitions. Are d-d transitions possible in diamagnetic complexes? Why does $\ce{[Co(NH3)6]^3+}$ show colour? ...
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Can Positive ions satisfy primary valences according to Werner's theory for coordination compounds?

My book (NCERT- Chemistry Part for class 12) Coordination Compounds-NCERT (Page-2) Mentions the following statements as a postulate of Werner's theory: The primary valences are normally ionisable and ...
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Why does low spin character predominate in hexafluoronickelate(IV)?

According to my book there are no unpaired electrons in $\ce{NiF6^2-}$. However, that should not be the case since fluoride is a weak field ligand. Why does hexafluoronickelate(IV) behave as a low ...
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How do you find oxidation state of the metals of a complex with two coordination spheres?

For example suppose we have $\ce{[Pt(NH3)4][PtCl4]}.$ For the naming of this complex I need to know the oxidation number of the metals; let the oxidation number of first and second $\ce{Pt}$ be $x, y$...
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Why brown ring complex is coloured?

In my textbook it is stated that brown ring complex formed during the test of nitrate ion is coloured due to charged transfer phenomenon but I think it is due to d-d orbital electron transition. Which ...
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3 votes
1 answer
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Can a carbon that has 5 bonds be explained by saying that one of its bonds is a coordination bond?

In my organometallic chemistry class at the university, the doctor told us that compound μ³-CO-[Fe₄(CO)₁₂]²⁻ had the structure that appears in the image. As you can see, there is a pentavalent carbon. ...
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Confusion in finding Effective Atomic Number of a complex

In finding EAN (Effective Atomic Number) of metal in complexes, I came over one compound: $\ce{[(CO)2RhH2Rh(CO)3 Cl]^+}$ Here the hydrogen are shown as bridging atoms and we are supposed to calculate ...
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Is triazanido(methyl)iron(IV) low-spin?

I was messing around on WebMO when I suddenly remembered that tetrakis(4-norbonyl)iron(IV) was diamagnetic, despite its tetrahedral coordination. Knowing that late metal complexes in extremely high ...
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9 votes
1 answer
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How does cyclopentadienyl anion act as reducing agent?

I am a second year university student, so I'm afraid my chemistry isn't great. I am looking for an explanation of how the $\ce{Cp-}$ anion acts as a reducing agent. To contextualise - in a simple ...
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Nature of Bisphosphonates Binding onto Hydroxyapatite in the Aqueous Phase

In many studies I've read, bisphosphonates (first image) are said to bind remarkably onto bone hydroxyapatite (second image) crystals. It was reported by J. Roelofs et al., (2008) that this mechanism ...
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Does the spin of electron in d half-filled d-orbital changes while forming low spin complex?

Recently I learned how VBT explains the formation of coordination complexes. But I am stuck at a point that seems hard to digest for me. Consider a metal ion having an electronic configuration as ...
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3 votes
1 answer
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Can nickel(IV) be stabilised in water using appropriate ligands?

Platinum(IV) is perfectly stable in water as its hexachlorido complex, and so is palladium(IV). However, nickel(IV) is not stable in water even in its hexafluorido complex- the exchange-inertness of ...
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Is tetraoxidocobaltate(V) low-spin

After hearing that hexaamminecobalt(III) and hexafluoridonickelate(IV) are both low-spin due to the central metals' high oxidation states(even though both bear pi-donor ligands), I began to wonder if ...
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2 votes
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Why are ligand orbitals always lower in energy than the metal orbitals in the ligand field theory?

The below image has been used to represent the ligand field theory for transition metals: (Source: https://chemed.chem.purdue.edu/genchem/topicreview/bp/ch12/ligand.php) Also, other similar images ...
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What are the Ionic Properties of Co-ordinate Covalent Bonds? [closed]

In my 10th grade book, it says that A coordinate bond has properties of both covalent and ionic bonds. Therefore, it is also called dative or co-ionic bonds. I understand that it has properties of ...
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2 votes
1 answer
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Spin-only magnetic moment of [Fe(en)(bpy)(NH₃)₂]²⁺

The one that can exhibit highest paramagnetic behaiour among the following is ($\ce{gly}$ is glycinato; $\ce{bpy}$ is 2,2ʹ-bipyridine): (a) $\ce{[Pd(gly)2]}$ (b) $\ce{[Fe(en)(bpy)(NH3)2]^2+}$ (c) $\ce{...
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Why does energy of non-axial d-orbitals decrease in an octahedral complex?

In an octahedral complex, if we assume the metal ion to be inside a cube then ligands will approach from its faces. So the axial d orbitals will experience more electronic repulsion as compared to ...
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1 answer
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Why total stereoisomers is 1 even if no geometrical isomers and optical-isomers are present [closed]

Let's for example take the complex structure type $\ce{MA_6}$, What will be the Total number of Stereo-isomers (=[Geometrical-isomers]+[optical-isomers]). My effort was that There will be no G.I and ...
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1 vote
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Total number of Isomers of [Co(NH3)5(NO2)](NO3)2 [closed]

I encountered this question in my country's Chemistry textbook of class 12. No solutions are published, but the answer given at the back states - "There are 10 possible isomers. (Hint: There are ...
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4 votes
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280 views

Does solvate isomers exist for coordination compounds with ammonia solvent as ligand?

I could find many sources confirming the hydrate isomerism(with water as solvent) but I couldn't find any information about any other solvent. In all the sources "hydrate/solvate isomerism" ...
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Is a tetrahedral complex with two symmetric bidentate ligands optically active?

If the shape of of a complex $\ce{M(AA)2}$ (with $\ce{AA}$, a bidentate ligand) is tetrahedral, then is it optically active? Currently I know that it is optically inactive, but I want to know the ...
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For a structure of a compouund optically active, what is the number of stereo isomers if no geometrical isomers are present?

Suppose for example the compounds $\ce{M(AA)3}$ and $\ce{M(AA)3bc}$, with $\ce{M}$, the central metal atom and $\ce{AA}$, a bidentate ligand. What is the total number of stereo-isomers of both? I was ...
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-2 votes
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Do strong field ligands always give d2sp3 hybridisation and weak field ligands give sp3d2 for coordiantion number 6 [closed]

i am actually doing coordination compounds but get confused when it comes to hybridization so wanted to create a short of mine for the exam
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1 answer
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Multiplicity prefixes for complex compounds with organic ligand

Consider the compound $[\ce{Ni(gly)_2}]$, with $\ce{gly}$ denoting glycinate ligand. Should the name be bis-(glycinato)nickel(II) or diglycinatonickel(II) In my book, it's written that the prefixes &...
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2 votes
1 answer
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How to "draw" a coordination bond (dashed bond) in MOLFILE?

How can we "draw" a coordination bond (dashed bond) in MOLFILE? I cannot find a bond property or option that would allow me to choose such a thing. So many drawings of organo-metallic ...
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5 votes
2 answers
487 views

What is the chemical composition of Ferrous Ferrocyanide?

To this day, iron-cyanide complexes confuses me. So, I want to settle this once and for all. After scavenging the internet, I gathered the following result: $$ \ce{Ferr} \color{blue}{\ce{ous}}~\ce{...
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Do coordination complexes with stronger ligands form more stable complexes?

I read that chelate complexes generally are more stable than monodentate complexes. However, I noticed that in the case of $\ce{[Fe(CN)6]^3-}$ and $\ce{[Fe(en)3]^3+}$, this is not observed as the ...
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how do i identify bridging ligands in a given complex

is there any way to identify bridged complexes ? my teacher just drew the complex and I failed to understand why OH should act as a brigding ligand... Im aware carbonyls generally act as bridging ...
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1 vote
1 answer
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Coordination number of metals in complexes

The co-ordination number of a metal is fixed in which way? My chemistry textbook says, " The secondary valence is equal to the coordination number and is fixed for a metal." Obviously, the ...
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Preparation of Ferrocene

Although many synthesis methods of ferrocene are discussed in literature, I want to know about the black precipitation which occurs when $\ce{FeCl2・4H2O}$ in $\ce{DMSO}$ solution reacts with ...
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Comparing intensity of colour in coordination compounds

I had given an examination recently in which the question asked was: Write the decreasing order for the intensity of color in $\ce{[CoCl4]^{2-}}$, $\ce{[Co(CN)4]^2-}$, $\ce{[Co(H2O)6]^2+}$ What my ...
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1 vote
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What should be the IUPAC name of (NH3)5Co-NH2-Co(NH3)4(H2O)]?

What should be the IUPAC name of $\ce{(NH3)5Co-NH2-Co(NH3)4(H2O)]}$? This is similar to $\ce{[(NH3)5Co-NH2-Co(NH3)5](NO3)5}$, i.e. μ-amido-bis[pentaamminecobalt(III)] nitrate. But the two parts are ...
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6 votes
1 answer
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What is the correct molecular orbital diagram for the d orbitals in platinum for the tetraammineplatinum(II) complex?

I am trying to construct the diagram of $\mathrm{d}$ orbitals in the tetraammineplatinum(II) complex. According to the angular overlap model, $\mathrm{d}$ orbitals are going to look like those in the ...
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1 vote
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Limitations on the 18-electron rule

The 18-electron rule and the corresponding methods for counting the total valence electrons of transition metal complexes are among the most useful basic tools in modern inorganic chemistry, ...
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Why does adding excess NaOH prove amphoteric nature?

When 3+ hexaaqua ions react with hydroxide ions, the following set of reactions occurs: When we get to stage 3, a neutral ion has formed, and a white precipitate is created. Now, we know that for ...
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3 votes
1 answer
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Why is [M(AB)2] a geometrical isomer?

Our teacher told us that for coordination number 4 and tetrahedral shape $\ce{[M(AB)2]}$ doesn't have a plane of symmetry, so it shows optical isomerism. What if we take a plane passing through the ...
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3 votes
1 answer
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Why does iron carbonyl have five carbonyl groups instead of six or four?

When finely divided iron combines with carbon monoxide, we get the complex $\ce{Fe(CO)_5}$. Why the number 5? It doesn't even relate to the orbital theory wherein we can see the number of empty and ...
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3 votes
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Action of Fuller's Earth on Marble and Limestone

Using Fuller's earth is a very common and harmless way to treat marble and limestone that has been damaged/corroded by atmostpheric pollutants such as PM2.5/PM10 carbon particles (Soot) , Oxides of ...
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6 votes
1 answer
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How to understand the chemical formula of Prussian blue complex w.r.t its crystal structure?

Note: Just to be clear, I do not refer to "complex molecules" (i.e. "complex" as "complicated"), but to actual complexes. I am trying to understand the structure of ...
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1 answer
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How can we predict the formula of a coordination compound by just knowing the ligand and central metal? [closed]

Question: On complete reaction of $\ce{FeCl3}$ with oxalic acid in aqueous solution containing $\ce{KOH}$, resulted in the formation of product A. The secondary valency of $\ce{Fe}$ in the product A ...
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7 votes
2 answers
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Can actinides form diamagnetic coordination complexes?

I am not sure how accurate I can predict the magnetic properties of actinide diamagnetic complexes, due to the fact that they share the F-block electron as Lanthanides, which are already tricky, ...
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3 votes
1 answer
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Which compound of these following have electrovalent, covalent, coordinate as well as hydrogen bond?

Which compound have electrovalent, covalent, coordinate as well as hydrogen bond ? A) $\ce{[Cu(H2O)4]SO4.H2O}$ B) $\ce{[Zn(H2O)6]SO4.H2O}$ C) $\ce{[Fe(H2O)6]SO4.H2O}$ D) $\ce{[Fe(H2O)6]Cl3}$ Answer ...
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