Phase description for a substance dissolved in a solvent other than water?

I'm trying to write an equation for which I have $\ce{CuI}$ dissolved in acetonitrile. Usually if you have a salt dissolved in water you can denote that using $\ce{(aq)}$, but is there a notation for substances dissolved in a solvent other than water?




IUPAC “Green Book” recommends to use $\mathrm{sln}$ for denoting a solution in general [1, p. 54], referring to earlier *Recommendations 1981. Appendix No. IV to Manual of Symbols and Terminology for Physicochemical Quantities and Units* [[2](https://doi.org/10/d783th), pp. 1240–1242].
This has been extensively covered in the following posts:


* [What is the standard way to denote physical states in a chemical reaction?](https://chemistry.meta.stackexchange.com/questions/4165/what-is-the-standard-way-to-denote-physical-states-in-a-chemical-reaction) (Meta)
* [Phase abbreviations for non-aqueous solutions](https://chemistry.stackexchange.com/questions/108173/phase-abbreviations-for-non-aqueous-solutions)


On the contrary, abbreviation $\mathrm{sol}$ is used to denote a *process* (typically a sub- or superscript to a symbol for a thermodynamic quantity), not state of matter [1, pp. 59–60]:



> 
> ### 2.11.1 Other symbols and conventions in chemical thermodynamics
> 
> 
> **(i) Symbols used as subscripts to denote a physical chemical process or reaction**
> These symbols should be printed in Roman (upright) type, without a full stop (period).
> 
> 
> $$
> \begin{array}{ll}
> \ldots \\
> \text{solution (of solute in solvent)} & \mathrm{sol} \\ 
> \ldots
> \end{array}
> $$
> 
> 
> 


Another reason not to use $\mathrm{sol}$ for denoting a state of aggregation is its ambiguity: $\mathrm{sol}$ is often used as an abbreviation for “solid”, as listed in *Appendix 10-2 Abbreviations, Acronyms, and Symbols* in ACS Style Guide [3, p. 197]



> 
> $$
> \begin{array}{ll}
> \ldots \\
> \text{sol} & \text{solid} \\
> \text{soln} & \text{solution} \\
> \ldots
> \end{array}
> $$
> 
> 
> 


Also, specialized literature on electrochemistry of non-aqueous solutions uses $\mathrm{sv}$ to denote *solvation* process separately, see e.g. [4, p. 27]:



> 
> $ΔH^\circ\_\mathrm{sv},$ $ΔS^\circ\_\mathrm{sv},$ $ΔG^\circ\_\mathrm{sv}$: Enthalpy, entropy, and Gibbs energy of solvation of the electrolyte
> 
> 
> 


With this obligatory standardization part, the simplest reaction can be written as


$$\ce{CuI(s) ->[CH3CN] Cu^+(sln) + I^-(sln)}$$


However, copper(I) is extremely stable in acetonitrile due to solvation [4, p. 33]:



> 
> ### Interactions by Back-Donation from $\mathrm{d^{10}}$-Cation to Solvent Molecules
> 
> 
> Acetonitrile (AN) has relatively small DN and usually solvates rather weakly to
> metal ions. However, it solvates very strongly to $\ce{Cu+},$ $\ce{Ag+}$ and $\ce{Au+},$ which are univalent $\mathrm{d^{10}}$-metal ions.
> This is because these metal ions have an ability to back-donate their electrons into a π\*-antibonding orbital of the $\ce{CN}$ group of AN, as shown by $\ce{CH3C#N\overleftarrow{\ce{:\bond{->}A}}g+}.$
> As a result, $\ce{Cu+}$ and $\ce{Ag+}$ in AN are stable and not easily reduced to metal, while the weakly solvated $\ce{Cu^2+}$ is very easily reduced to $\ce{Cu+}$ … , making $\ce{Cu^2+}$ in AN a strong oxidizing agent.
> 
> 
> 


and may theoretically be coordinated by up to five acetonitrile ligands [[5](https://doi.org/10/ckvsxw)] with C.N. 4 being the most common unless there are other ligands.
Copper(I) and iodide don't seem to form a complex in acetonitrile [[6](https://doi.org/10/bqvn5f), p. 194]:



> 
> Also in tetraethyl­ ammonium iodide and thiocyanate solutions, the dissociation is seemingly complete, … while a slight association is indicated for bromide … and, especially, chloride.
> 
> 
> 


To sum it up, upon dissolving of copper(I) iodide in acetnitrile the formation of tetrakis(acetonitrile-*N*)copper(I) is the most likely scenario so that the final reaction can be written as


$$\ce{CuI(s) + 4 CH3CN(l) ->[CH3CN] [Cu(CH3CN)4]^+(sln) + I^-(sln)}$$


It should be noted that in a presence of better coordinating ligands $\ce{L}$ composition of the complex may, of course, vary $(\ce{[Cu(CH3CN)\_xL\_y]^z+}).$
Also, copper(I) iodide may form various coordination polymers based on $\ce{(CuI)\_n}$ cluster core [[7](https://doi.org/10/f37kdx), [8](https://doi.org/10/f6pnff), [9](https://doi.org/10/f7cjk2)].


### References


1. IUPAC “Green Book” Quantities, Units, and Symbols in Physical Chemistry, 3rd ed.; Cohen, R. E., Mills, I., Eds.; *IUPAC Recommendations; RSC Pub: Cambridge, UK*, **2007**. ISBN 978-0-85404-433-7.
2. Cox, J. D. Notation for States and Processes, Significance of the Word Standard in Chemical Thermodynamics, and Remarks on Commonly Tabulated Forms of Thermodynamic Functions. *Pure and Applied Chemistry* **1982**, 54 (6), 1239–1250. <https://doi.org/10/d783th>. (Free Access)
3. The ACS Style Guide: Effective Communication of Scientific Information, 3rd ed.; Coghill, A. M., Garson, L. R., Eds.; *American Chemical Society; Oxford University Press: Washington, DC; Oxford; New York*, **2006**. ISBN 978-0-8412-3999-9.
4. Izutsu, K. Electrochemistry in Nonaqueous Solutions; *John Wiley & Sons,* **2005.** ISBN 978-3-527-60065-6.
5. Vitale, G.; Valina, A. B.; Huang, H.; Amunugama, R.; Rodgers, M. T. Solvation of Copper Ions by Acetonitrile. Structures and Sequential Binding Energies of $\ce{Cu + (CH3CN)\_x},$ $x = 1−5,$ from Collision-Induced Dissociation and Theoretical Studies. *J. Phys. Chem. A* **2001**, 105 (50), 11351–11364. <https://doi.org/10/ckvsxw>.
6. Ahrland, S.; Nilsson, K.; Tagesson, B.; Haaland, A.; Schilling, B. E. R.; Seip, R.; Taugbøl, K. Thermodynamics of the Copper(I) Halide and Thiocyanate Complex Formation in Acetonitrile. *Acta Chem. Scand.* **1983**, 37a, 193–201. <https://doi.org/10/bqvn5f>.
7. Knorr, M.; Guyon, F.; Khatyr, A.; Strohmann, C.; Allain, M.; Aly, S. M.; Lapprand, A.; Fortin, D.; Harvey, P. D. Construction of $\ce{(CuX)\_{2n}}$ Cluster-Containing ($\ce{X} = \ce{Br}, \ce{I}$; $n = 1, 2$) Coordination Polymers Assembled by Dithioethers $\ce{ArS(CH2)\_mSAr}$ ($\ce{Ar} = \ce{Ph},$ $\ce{\textit{p-}Tol}$; $m = 3, 5$): Effect of the Spacer Length, Aryl Group, and Metal-to-Ligand Ratio on the Dimensionality, Cluster Nuclearity, and the Luminescence Properties of the Metal–Organic Frameworks. *Inorg. Chem.* **2012**, 51 (18), 9917–9934. <https://doi.org/10/f37kdx>.
8. Knorr, M.; Khatyr, A.; Dini Aleo, A.; El Yaagoubi, A.; Strohmann, C.; Kubicki, M. M.; Rousselin, Y.; Aly, S. M.; Fortin, D.; Lapprand, A.; et al. Copper(I) Halides $(\ce{X} = \ce{Br}, \ce{I})$ Coordinated to Bis(Arylthio)Methane Ligands: Aryl Substitution and Halide Effects on the Dimensionality, Cluster Size, and Luminescence Properties of the Coordination Polymers. *Crystal Growth & Design* **2014**, 14 (11), 5373–5387. <https://doi.org/10/f6pnff>.
9. Knorr, M.; Bonnot, A.; Lapprand, A.; Khatyr, A.; Strohmann, C.; Kubicki, M. M.; Rousselin, Y.; Harvey, P. D. Reactivity of $\ce{CuI}$ and $\ce{CuBr}$ toward Dialkyl Sulfides RSR: From Discrete Molecular $\ce{Cu4I4S4}$ and $\ce{Cu8I8S6}$ Clusters to Luminescent Copper(I) Coordination Polymers. *Inorg. Chem.* **2015**, 54 (8), 4076–4093. <https://doi.org/10/f7cjk2>.


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