Monodentate S-vs. bidentate 1,5-O,S-coordination of N-phosphoryl-N′-(R)-thioureas with Pd(II)

Reaction of N-phosphorylated thioureas of common formula RNHC(S)NHP(O)(OiPr)2 (R = tBu, HLI; R = Ph, HLII; R = 4′-benzo-15-crown-5, HLIII) with Pd(PhCN)2Cl2 in acetonitrile leads to complexes of the structure Pd(HLI-S)2Cl2 (1), Pd(HLII-S)2Cl2 (2) and Pd(HLIII-S)2Cl2 (3). Reaction of N-phosphorylated thioureas of common formula RC(S)NHP(O)(OiPr)2 (R = Et2N, HLIV; R = morpholine-N-yl, HLV) in the same conditions leads to complexes Pd(LIV-O,S)2 (4) and Pd(LV-O,S)2 (5), where the palladium(II) atoms are coordinated in a square-planar fashion by the C{double bond, long}S sulfur atoms and the P{double bond, long}O oxygen atoms of two anionic ligands. The crystal structure of complex 1 has been investigated by X-ray crystallography. It was established that the thiourea ligands are in a trans-configuration and the palladium(II) cation is coordinated by the sulfur atoms of the C{double bond, long}S groups and the chlorine atoms. Complex 1 is the first example of palladium(II) complex in which the potentially chelating N-phosphorylated thiourea ligand is bound through the sulfur atom only. © 2008 Elsevier Ltd. All rights reserved