Can carbon and titanium form an ionic bond because they both have four valence electrons? If titanium transfers four electrons to carbon, we get $\ce{Ti^4+}$ and $\ce{C^4-}$ which both have noble gas configurations.
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asked Jan 20, 2016 at 2:15
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4$\begingroup$ TiC is interstitial, metallic carbide en.wikipedia.org/wiki/Carbide $\endgroup$– MithoronJan 20, 2016 at 12:35
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2 Answers
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See Kuiying Chen, Sami Kamran, Bonding Characteristics of TiC and TiN, Modeling and Numerical Simulation of Material Science, Volume 3, Number 1, , 2013 PP. 7-11 doi 10.4236/mnsms.2013.31002 From the abstract:
Using ab initio density functional theory calculations, the electron localization function (ELF) of typical transition metal carbide TiC and nitride TiN were computed and analyzed to reveal their nature of the chemical bonds. The ELF approach was initially validated through typical examples of covalent-bonding Diamond (C) and ionic-bonding sodium chloride NaCl. Our results clearly demonstrate the dominantly ionic bonding characteristics of TiC and TiN.
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$\begingroup$ It is better to spend some time discussing what the literature says $\endgroup$ Feb 14, 2019 at 16:56
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Yes, carbon can form ionic bonds with Titanium. $\ce{TiC}$ is titanium carbide, an ionic compound with $\ce{C^{4-}}$ (the carbide anion) and $\ce{Ti^4+}$ (titanium cation). It has the same crystal structure as $\ce{NaCl}$ (which probably has to do with the $\ce{1\!\!:\!1}$ ratio of anion to cation).
This is a space filling model of titanium carbide:
Here is sodium chloride for a crystal comparison (click the image for a larger version):
The second model (the $\ce{NaCl}$) shows the ionic bonds as covalent bonds but still, both titanium carbide and sodium chloride have a cubic lattice structure.
However, carbon does not often form ionic bonds with metals since it prefers to be covalent (much like oxygen). In fact carbon has much more covalent character than oxygen does which is why oxides form easily (just $\ce{O2 + element}$ and usually, oxides will form) but carbides don't (a catalyst is needed to form carbides and some oxides like gold oxide).
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6$\begingroup$ Is TiC really completely ionic? Or is it "partially" ionic that it still shares electrons some way, like through dative bonds to stabilize the system? $\endgroup$ Jan 20, 2016 at 4:02
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2$\begingroup$ Also, Caters, please cite your sources for where you obtained these images! $\endgroup$– hBy2PyJan 20, 2016 at 4:14
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2$\begingroup$ TiC is hardly ionic at all. To begin with, it would not hydrolyze. $\endgroup$ Jan 20, 2016 at 7:01
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$\begingroup$ Not all ionic compounds are soluble in water. Take for example Calcium fluoride. It isn't soluble in a lot of solvents because of the calcium ions but it is most surely ionic. So just because TiC isn't soluble in water does not mean that it is not ionic. $\endgroup$– CatersJan 20, 2016 at 7:08
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3$\begingroup$ I never said "soluble". I said "hydrolyze", and that's what ionic carbides typically do, because hydrocarbons are much weaker acids than water. This has very little to do with solubility. $\ce{Al4C3}$, for example, hydrolyzes quite readily, but isn't water-soluble in any meaningful sense, nor are the products of its hydrolysis. $\endgroup$ Jan 20, 2016 at 8:20