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Why is it wrong to use the concept of hybridization for transition metal complexes?

Tetrahedral complexes Let's consider, for example, a tetrahedral $\ce{Ni(II)}$ complex ($\mathrm{d^8}$), like $\ce{[NiCl4]^2-}$. According to hybridisation theory, the central nickel ion has $\mathrm{...
orthocresol's user avatar
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54 votes

Why do compounds like SF6 and SF4 exist but SH6 and SH4 don't?

TL;DR Fluorine is electronegative and can support the extra negative charge that is dispersed on the six X atoms in $\ce{SX6}$, whereas hydrogen cannot. First, let's debunk a commonly taught myth, ...
orthocresol's user avatar
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46 votes
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Are the lone pairs in water equivalent?

Water, as simple as it might appear, has quite a few extraordinary things to offer. Most does not seem to be as it appears. Before diving deeper, a few cautionary words about hybridisation. ...
Martin - マーチン's user avatar
22 votes

Why does bond angle decrease in the order H2O, H2S, H2Se?

The question asks why water has a larger angle than other hydrides of the form $\ce{XH2}$ in particular $\ce{H2S}$ and $\ce{H2Se}$. There have been other similar questions, so an attempt at a general ...
porphyrin's user avatar
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21 votes
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Hybridization of nitrogen in trisilylamine, (SiH3)3N?

Ordinarily and according to Bent’s rule, we would expect nitrogen’s lone pair to be in an $\mathrm s$ orbital and nitrogen using its three $\mathrm p$ orbitals to form three bonds to the three silicon ...
Jan's user avatar
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21 votes
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Hybridisation of ClO2

I actually take issue with the question (which was asked of you not by you), as I think this oversimplifies a molecule, that still isn't well understood in the first place. That is why I find this ...
Martin - マーチン's user avatar
19 votes
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What is Drago's rule? Does it really exist?

Going through what you posted, I think ‘Drago’s rule’ (which I never encountered, either at school or at university) gives good predictions but uses a largely terrible set of arguments. For any atomic ...
Jan's user avatar
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19 votes

Hybridization of nitrogen in trisilylamine, (SiH3)3N?

To test Jan's argument, I did an NBO analysis of your structure (optimized at PBE-D3/def2-SVP with NWChem 6.6 using a conformational search with MMFF94s and Avogadro as the starting point; a frequency ...
schneiderfelipe's user avatar
18 votes
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Is the phenyl cation or ethynylium more stable?

Preamble As trivial as this question might seem, it is not. It should certainly never be asked in at an exam level lower than basic quantum chemistry. Any of the tempting explanation schemes will ...
Martin - マーチン's user avatar
17 votes
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Does s stand for sigma bond and p for pi bond?

You got it backwards. The $\mathrm{s}$, $\mathrm{p}$, $\mathrm{d}$, $\mathrm{f}$ orbitals stand for sharp, principal, diffuse, and fundamental. Wikipedia: Electron Configuration § Notation: The ...
DHMO's user avatar
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17 votes
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Shape of sp³ hybrid orbital

Don't put too much trust in the absolute signs of wavefunction, for they all are arbitrary anyway. Look at it this way: an s orbital has one sign (*). One lobe of p orbital has the same sign, so when ...
Ivan Neretin's user avatar
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15 votes
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Predicting sigma bond overlap strengths of s-s, p-p, s-p, sp-sp etc

I think the issue might be what orbitals are being referred to. Both books could be correct if they are referring to different $\mathrm{p-p}$ overlap. For example, suppose two atoms are bonding along ...
Tyberius's user avatar
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15 votes
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How can the hybridisation schemes of transition metal complexes be determined?

Firstly, note that hybridisation theory as applied to transition metal complexes is an incorrect, flawed theory. It is an attempt to rationalise experimental observation (e.g. geometries), but in the ...
orthocresol's user avatar
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14 votes
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Why is cyclopropane more acidic than propane

Indeed, according to the Evans $\mathrm{p}K_\mathrm{a}$ table the cyclopropane $\ce{C-H}$ bond $(\mathrm{p}K_\mathrm{a} \approx 46)$ is more acidic than the $\ce{C-H}$ bond on the central carbon in ...
ron's user avatar
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14 votes
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What is the hybridization of terminal fluorine atoms in molecules like boron trifluoride?

TL;DR: As a rule of thumb, terminal (heavy) atoms are almost always best described as having sp hybrid orbitals (at the most). For more on this, I refer you to my answer on What is the hybridization ...
Martin - マーチン's user avatar
13 votes

What is the hybridisation of trifluoromethyl free radical?

Hyperconjugation between the orbital that contains the lone pair and the $\ce{C-F}$ antibonding orbital contributes to the pyramidalization of $\ce{CF3^·}$ radical: In the planar geometry the ...
EJC's user avatar
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12 votes

Hybridization of sulfur in sulfur dioxide

The structure of sulfur dioxide ($\ce{SO2}$) is quite complicated. The image from socratic.org* explains it quite well, please find the $\ce{SO2}$ hybridization diagram via the Internet Archive. As ...
Kenny Lau's user avatar
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12 votes

Why are axial bonds are longer than equatorial bond in sp3d hybridized atoms?

You are asking for $\mathrm{sp^3d}$ hybridisation, but I do not know of a case where $\mathrm{sp^3d}$ hybridisation actually happens. Either it does not make sense to discuss hybridisation at all (the ...
Jan's user avatar
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12 votes
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How are the hybrid orbitals of sulfur hexafluoride shaped?

If you limit consideration to hybridization of atomic orbitals, a good reference to see is On the role of d orbitals in sulfur hexafluoride J. Am. Chem. Soc., 1986, 108 (13), pp 3586–3593. First, it ...
DavePhD's user avatar
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11 votes

Hybridisation of Mn in potassium permanganate

I feel a bit like a broken record: Do not use hybridisation to describe coordination compounds; it is not helpful. However, the case of permanganate stands out as something where hybridisation is ...
Jan's user avatar
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11 votes
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Why is sulfur unhybridized in dimethyl sulfide?

We can immediately discard $\ce{SiH4}$ — a tetrahedral molecule can never be unhybridised. We can also pretty quickly discard $\ce{SO2}$. The dated description of this molecule included octet ...
Jan's user avatar
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11 votes

How do I compare the C=C bond lengths in this cumulene?

Label the double bonds (a), (b), and (c), in correspondence with the image provided in the question. Label the carbons in the cyclopropane ring $\ce{A}$, $\ce{B}$, and $\ce{C}$, with $\ce{A}$ being ...
a-cyclohexane-molecule's user avatar
11 votes
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Bonding in hypervalent molecules

The starting point for a discussion should be the observed structures. $\ce{SF6}$ has a regular octahedral geometry with bond lengths of 1.56 Å. Below is a depiction compared with some other compounds ...
Karsten's user avatar
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10 votes

Hybridization of Cu2+ in tetraamminecopper(II) sulfate complex

I feel a bit like a broken record. Do not use hybridisation to describe coordination compounds; it is not helpful. The cation you called tetraamminecopper(II) is more accurately described as ...
Jan's user avatar
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10 votes

How are the hybrid orbitals of sulfur hexafluoride shaped?

Hybridisation is determined by geometry! This is the number one thing that you should learn from this answer. If you know the geometry of a molecule then you can work out the hybridisation of the ...
bon's user avatar
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10 votes
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Why is ammonia more basic than acetonitrile

p orbitals are higher in energy than s orbitals. sp3 orbitals with 75% p-character are therefore higher in energy than sp orbitals with 50% p-character. This means that the lone pair in ammonia is ...
orthocresol's user avatar
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10 votes

Is there a shortcut method to calculate the Steric Number?

Short answer: no. The steric number is a property of an atom, not a compound. You need to know what an atom connected to a given atom to know its steric number. For simple compounds, you can usually ...
Ben Norris's user avatar
10 votes

Why is it wrong to use the concept of hybridization for transition metal complexes?

For the most part, coordination bonds involve d electrons from the transition metal interacting with some other electrons on a separate molecule. Hybrid orbitals are constructed from a single atom's ...
MasterYoda's user avatar
10 votes

What is the hybridization of chlorine in vinyl chloride?

Disclaimer: An important point to remember is, that hybridisation always follows the molecular structure, it is never the cause for a certain structure. As such, hybridisation is an interpretation ...
Martin - マーチン's user avatar
10 votes
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Are carbocations necessarily sp2 hybridized and trigonal planar?

I actually have a (or many) big issue(s) with the quote: The central C-atom is in an sp2 hybridized state, for which the carbocations have planar geometry. The p$z$-AO remains empty. The authors ...
Martin - マーチン's user avatar

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