Donatu V was the fifth planet of the Donatu planetary system. The planet was located near Sherman's Planet and the Federation-Klingon border. Ownership of this planet, as well as the rest of the region, was disputed between the United Federation of Planets and the Klingon Empire from the point of first contact through the late 2260s.
The inconclusive Battle of Donatu V, one of the few brush wars fought between the two powers during the Federation-Klingon Cold War, was fought here in 2245. (TOS: "The Trouble with Tribbles")
In 2374, during the Dominion War, the IKS Rotarran was ordered to escort a convoy of Klingon cargo vessels, which included the IKS Par'tok, to Donatu V. (DS9: "Sons and Daughters")
According to the Star Trek: Star Charts (pg. 60, 64), The Donatu system was a single star system. Donatu was a G-class star with a magnitude of -1, which was a hundred times brighter than Sol.