Complex sentence: In May 2010, the company announced the appointment of Frédéric Chaslin as the company's next chief conductor, effective 1 October 2010, with an initial contract of three years, but, in August 2012, Chaslin resigned as the Opera's chief conductor.
Split into simpler sentences: In May 2010, the company announced the appointment of Frédéric Chaslin as the company's next chief conductor, effective 1 October 2010, with an initial contract of three years. However, in August 2012, Chaslin resigned as the Opera's chief conductor.