Members of the board of the CBS Corporation are negotiating with the company’s chairman and C.E.O., Leslie Moonves, about his departure. Sources familiar with the board’s activities said the discussions about Moonves stepping down began several weeks ago, after an article published in the The New Yorker detailed allegations by six women that the media executive had sexually harassed them, and revealed complaints by dozens of others that the culture in some parts of the company tolerated sexual misconduct. Since then, the board has selected outside counsel to lead an investigation into the claims.