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Recently, I have answered a question "Comparing explosive properties of mercury(II) cyanate and mercury(II) fulminate" where stability of cyanate vs fulminate was discussed. While I was answering that question, I found out that fulminate vs cyanate stability was previously discussed when chemical isomerism was discovered by Liebig and Wohler. They both reported independently that cyanic acid and fulminic acid that apparently had the same composition had very different characteristics and so they worked on the corresponding silver salts. These two compounds had the same chemical composition, yet are chemically different. Silver(I) fulminate is explosive, while silver(I) cyanate is a stable compound.

My thought process is that since silver(I) cyanate and silver(I) fulminate were extensively discussed to explain chemical isomerism, could that be applied for corresponding mercury compounds i.e mercury(II) cyanate and mercury(II) fulminate so that I could answer the previous question which was asking for the stability/explosive properties of mercury(II) fulminate and mercury(II) cyanate. Mercury fulminate is well known in explosive industry and is used commercially. OTOH, mercury(II) cyanate is not known(?). I could hardly find any information of this compound, So, I assumed (incorrectly?) that mercury(II) cyanate doesn't exist and any attempts to isolate the compound would decompose explosively to a stable compound. I also found mercury(II) cyanate as one of the decomposition intermediate of mercury(II) fulminate:

$$\ce{4 Hg(CNO)2 → 2 CO2 + N2 + HgO + 3 Hg(OCN)CN} \\ \ce{Hg(CNO)2 → 2 CO + N2 + Hg} \\ \ce{Hg(CNO)2 → :Hg(OCN)2} \\ \ce{2 Hg(CNO)2 → 2 CO2 + N2 + Hg + Hg(CN)2} $$

Also, I found in some e-books (see below) that $\ce{Hg(OCN)2}$ was apparently called mercury(II) fulminate which is clearly wrong which gave me a notion that mercury(II) cyanate never existed/discovered. So, my questions are:

  1. Does mercury(II) cyanate exist?
  2. Fulminates are considered unstable and sensitive than cyanates and thus difficult to isolate. So, in this case mercury(II) fulminate should be more unstable and sensitive than mercury(II) cyanate and yet the latter one hasn't been isolated yet. Why?

Books:

  1. Mercury study report to Congress, DIANE Publishing
  2. Accounting for Resources, 2: The Life Cycle of Materials by Robert U. Ayres, Leslie Ayres, Leslie W. Ayres, Edward Elgar Publishing, 25-Nov-1999, Nature, 380 pages
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  • $\begingroup$ Sadly no answer to your question but as you did some research on the topic, do you know if something like silver cyanate + mercury(II) chloride has been tested and studied so far? $\endgroup$ Aug 13 '20 at 8:18
  • $\begingroup$ "mercury(II) cyanate should be more stable and less sensitive than mercury(II) fulminate" and therefore so useless that it's totally overshadowed by better known isomer. $\endgroup$
    – Mithoron
    Aug 17 '20 at 0:04
  • $\begingroup$ "The Chemistry of Mercury" by Charles Andrew McAuliffe says only what @Justanotherchemist said + that reaction's in methanol. So, it exists, but people generally don't are about it. $\endgroup$
    – Mithoron
    Aug 17 '20 at 0:19

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