Heterocyclic-2-thione derivatives of metals incorporating cyclopalladated azobenzenes of variable nuclearity and N,S-bridged 1D polymer of [bis(pyridine-2-thiolato)mercury()]

In this investigation, the reactivity of azobenzene-based cyclopalladated precursors with a series of heterocyclic-2-thiones is described. Reactions of the precursor, [Pd 2 (μ-Cl) 2 -(κ 2 :C,N-deazb) 2 ], with pyridine-2-thione (pytH), or pyrimidine-2-thione (pymtH), yielded the red-brown dinuclear compounds [Pd 2 (μ-N,S-pyt) 2 (κ 2 :C,N-deazb) 2 ] ( 1 ) and [Pd 2 (μ-N,S-pymt) 2 (κ 2 :C,N-deazb) 2 ] ( 2 ) (deazbH = 4,4′-diethoxyazobenzene). A similar reaction of [Pd 2 (μ-Cl) 2 (κ 2 :C,N- p -mazb) 2 ] with N -phenyl-imidazolidine-2-thione (imdtH-NPh) yielded a trinuclear compound, [Pd 3 (μ-N,S-imdt-NPh) 4 (κ 2 :C,N-pmazb) 2 ] ( 4 ) (pmazb = p -methoxyazobenzene). A direct reaction of PdCl 2 with azobenzene (azbH) and N -methyl-imidazolidine-2-thione (imdtH-NMe) afforded a mononuclear compound, [Pd(κ 1 S-imdtH-NMe)Cl(κ 2 :C,N-azb)] ( 3 ). In the compounds 1 , 2 and 4 , the thio-ligands, pyt − , pymt − and imdt-NPh − are coordinating as anions with N,S-bridging ( 1 , 2 , 4 ) and in compound 3 , imdtH-NMe is coordinating as a neutral ligand through the S-donor atom only. Compounds 1-4 are luminescent in the visible region. A reaction of HgCl 2 with azobenzene (azbH), and pyridine-2-thione in DMF, did not yield the cyclometallated compound, [Hg 2 (μ-N,S-pyt) 2 (κ 2 :C,N-azb) 2 ]; rather, it afforded two coordinate compounds, [Hg(κ 1 S-pyt) 2 ] ( 5 ), with polymerisation occurring via weak N Hg bonds. In this investigation, the reactivity of azobenzene-based cyclopalladated precursors with a series of heterocyclic-2-thiones is described.