His compatriot David Neville was second in 45.70 seconds and Britain's Michael Bingham was third in 45.84.
Ethiopia's Sentayehu Ejigu clocked a personal best as she sprinted clear to win the women's 5,000m in 14.30.96 while Kenya's Augustine Choge just held off fast-finishing teammate Asbel Kiprop to win the men's 1,500m in a world-leading 3.32.20.
Australian world champion Steve Hooker looked rusty after a six week break. He failed to clear a normally routine 5.70 meters as Germany's Malte Mohr won the men's pole vault.
Australia's Fabrice Lapierre jumped a season's best 8.30m to win the men's long jump with a comfortable 12 centimeters margin over American Dwight Phillips.
The Diamond League awards points depending on performances throughout the 14-event program with the winners of the 16 meets taking home a diamond trophy and cash prize.