There’s something about boron
Boron’s chemistry is as much defined by what it isn’t – carbon, or a metal – as by what it is. Recent years have started to fix this misconception, as James Mitchell Crow reports
Like any element, boron’s reactivity reflects its position in the periodic table. But boron’s position – a non-metal on top of group 13 – is more eventful than most. Like beryllium and lithium, its neighbours to the left, and aluminium, its closest group 13 sibling just below, boron chemistry is characterised by its electropositivity: the quintessential boron compound is therefore electron deficient: an electrophile and a Lewis acid. But over the past decade, boron chemistry has been steadily subverted. A string of boron compounds in exotic bonding states have turned the element’s behaviour on its head. Boron can be coaxed into become a strong nucleophile, a Lewis base, an electron donor. Boron chemists Holger Braunschweigh, Doug Stephan and Rebecca Melen tell us about the mysterious fifth element.