It seems very difficult to match up the pendulous flower clusters with pinnately compound leaves, but how about
Staphylea colchica, Caucasian bladdernut as a tentative possibility - at least until the flowers open completely?
http://www.plantae.ca/Staphyle...
http://en.wikipedia.org/wiki/S...
http://www.missouribotanicalga...
There's also a
Staphylea pinnata which I think has wider distribution. If it was sold as an ornamental, though, the native range isn't necessarily going to be all that useful.
http://www.imagines-plantarum....
The leaves look a little closer to
S. colchica in some of the pictures though.
