Subject: shorter bond = Weaker/More reactive bond?

From: "Rzepa, Henry" <[email-masked]>
Date: Wed, 9 May 2001 17:43:44 +0100

I came across a claim last week that in a  square planar
Pd complex for which a structure had been determined, the
shorter of two  Pd-ligand bonds was also the more labile.

Shorter of course cannot be formally equated with "more reactive",
but in general we tend to assume that if a bond is to break, the
"least motion" path is normally favoured.

There are of course many examples of non-least-motion
reactions, but  does anyone know of any (other)  
clear cut cases of bonds where 
the shorter bond is the more reactive?
-- 

Henry Rzepa. +44 (0)20 7594 5774 (Office) +44 (0870) 132-3747 (eFax)
Dept. Chemistry, Imperial College, London, SW7  2AY, UK. 
http://www.ch.ic.ac.uk/rzepa/