We present the results of a weakly modeled burst search for gravitational waves from mergers of nonspinning intermediate mass black holes in the total mass range 100–450  M⊙ and with the component mass ratios between 1∶1 and 4∶1. The search was conducted on data collected by the LIGO and Virgo detectors between November of 2005 and October of 2007. No plausible signals were observed by the search which constrains the astrophysical rates of the intermediate mass black holes mergers as a function of the component masses. In the most efficiently detected bin centered on 88+88  M⊙, for nonspinning sources, the rate density upper limit is 0.13 per Mpc3 per Myr at the 90% confidence level. © 2012 The American Physical Society