Does mercury(II) cyanate exist?

Question

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 already pointed out when chemical isomerism was discovered by Liebig and Wohler. They both reported independently and concluded that silver(I) fulminate is explosive while silver(I) cyanate is a stable compound.

I was wondering if chemical isomerism can be applied to discuss mercury(II) cyanate and mercury(II) fulminate stability since it was already applied for corresponding silver salts. Mercury fulminate is well known in explosive industry and is used commercially. OTOH, mercury(II) cyanate is not known/vaguely known as I could not find any information of this compound, So, I assume (incorrectly?) that mercury(II) cyanate doesn't exist and any attempts to isolate the compound would decompose explosively. Moreover, mercury(II) cyanate is one of the decomposition intermediate of mercury(II) fulminate

Questions:

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?

Answer 1

After digging, I was able to find out some information on Mercury(II) cyanate and yes it exists. From (1):

Mercuric cyanate, $\ce{Hg(OCN)2}$ is obtained as a white, crystalline precipitate by adding a solution of potassium cyanate to one of mercuric chloride.

I was also right that any attempts to isolate the compound would decompose explosively. Below is a good explanation of cyanate vs fulminate stability and more on mercury (II) cyanate behavior:

Disregarding the difference in structure, it was argued that because the empirical formulae of fulminate and cyanate are identical, metal cyanate are likely to be as unstable as metal fulminates. The result of practical tests, in which samples of various metal cyanates were heated in a flame, coupled with long industrial experience of the use of molten salt process baths containing over 40% of cyanates, show that the assumption on explosive instability of metal cyanates is not warranted. The observation that silver or copper(II) cyanates burned smoothly on exposure to flame suggests that the explosion recorded for silver cyanate (ibid.) may have involved close confinement of other unusual conditions during heating.

Although mercury(II) cyanate (ibid.) vaporized gradually and completely without flaming on heating, two incidents of explosion during grinding or crushing operations have been recorded. The unusual tendency for many derivates of silver and mercury to decompose forcefully (with separation of the metal, rather than the oxide as with other metals), suggest that the other metal cyanates are likely to be rather more stable. This view is supported by available thermodynamic data, which show that while several cyanides are endothermic compounds, the few cyanates for which figures are quoted are all exothermic compounds and unlikely to be intrinsically unstable. A few reports of mishap could involve hydrolysis of the cyanate liberating ammonia, followed by formation of "fulminating" noble metals.

References:

1. A Text-book of Chemistry, Volume 1 by Samuel Philip Sadtler, Virgil Coblentz, 1900
2. TREATISE ON CHEMISTRY by H.E. Roscoe, C. Schorlemmer, 1902
3. Bretherick's Handbook of Reactive Chemical Hazards: An indexed guide to published data by Peter Urben, Elsevier, 2016