Some emails and discussions with colleagues have raised an important point to be learned from the recent TMS-diazomethane tragedies. Many people are probably taking some of these reagents less seriously than they should.
As organic chemists know, the trimethylsilyl group is a strange beast, and can often substitute for a proton in small reagents. That often gives such compounds new and useful properties along the way – for example, hydrazoic acid (hydrogen azide) is an extremely dangerous substance because of its unpredictable explosive qualities. It should never be generated except in very dilute solution (that is, unless you’re prepared at every moment for a serious detonation, and not many people are). But the corresponding trimethylsilyl azide is an article of commerce – you can pick up the phone and order a bottle. No one in the history of the fine chemical industry, as far as I know, has been crazed enough to offer hydrazoic acid for sale. How could it be delivered - by trained hummingbirds?
But the two reagents can do many of the same transformations, since the TMS group is often just about as easy to lose at the end of the reaction as a proton is. The exact same situation obtains with trimethylsilyldiazomethane: no one’s ever tried to sell or ship the parent compound, but solutions of the TMS derivative are ready to be ordered at your convenience.
But that's only because they're less explosive. All the TMS reagents are just as poisonous as their proton counterparts. And that's where I think some chemists aren't making the connection. We treat diazomethane gingerly because we don't want it to explode, but we should also be handling it like the volatile toxin it is. The same goes for hydrazoic acid. If you have to deal with the stuff, you're mostly thinking every second about how it could go off on you. But you should also be thinking about how it's a potent, poisonous vasodilator. It doesn't have to blow up: a good deep gust of it will relax your arterial walls permanently by killing you, and TMS azide will do the exact same thing.
These compounds are intrinsically toxic, and they're also toxic because they'll hydrolyze back to the parent compounds in a warm, wet environment - like the inside of your lungs. I think that people treat another one of the series, trimethylsilyl cyanide, with more respect. That's because HCN gets a lot of respect for its inhalation toxicity (and with damned good reason), and opening an ampoule of TMS-CN is (or should be) a reminder that it's just as nasty. And since it doesn't explode, that's the main thing that you think about.
So spread the word: these reagents, though extremely useful, are not to be handled lightly. They're volatile and they're just as poisonous as their parents. The ease of ordering and handling them, in fact, may make them even more of a potential hazard. Treat 'em with respect.
Note: for those looking for a thorough reference work on the subject, this seems like an up-to-date choice.