Reactivity of 1,3-bis(2-pyridyl)benzene, N boolean AND CH boolean AND N, with gold(III) chlorides: salts, adducts and cyclometalated pincer derivatives. Crystal and molecular structures of [HN boolean AND CH boolean AND N][AuCl4], [Au(N boolean AND C boolean AND N)Cl][PF6] and [Au(N boolean AND C boolean AND N)Cl(PPh3)(2)][PF6]