Dimethylmercury is an extremely toxic organomercury compound with the formula (CH3)2Hg. A volatile, flammable, dense and colorless liquid, dimethylmercury is one of the strongest known neurotoxins. Less than 0.1 mL is capable of inducing severe mercury poisoning resulting in death.

I remember hearing the story of Karen Wetterhahn, a chemistry professor who specialized in toxic metal exposure and who was using all of the recommended precautions, who got a couple of drops of the stuff on a glove and died less than a year later.

From what I could find organomercury compounds are a lot more bioavalable and penetrates into places in the body that elemental mercury wouldn't, for instance, the brain. It will not only penetrate the skin, it will also penetrate gloves.Also high toxicity, methylmercury has an LD50 of 20 mg/kg for certain monkeys for acute toxicity. But a single drop can kill you from prolonged mercury poisoning because it just stays in the body. But honestly dying would be better than surviving it.

As chemists were taught early on not to fuck around with organic mercury. Same with HF.

I assume Derek Lowe wrote about it at some point.

He has a running series on dangerous chemicals.

https://www.science.org/content/author/derek-lowe