Reactions of halogens with Pt(II)complexes of N-alkyl-and N,N-dialkyl-N'-benzoylthioureas:oxidative addition and formation of an h inclusion compound

摘要

The treatment of cis-[Pt~II(L~(1a/b)-S,O)_2] complexes of N,N-diethyl-(HL~(1a))and N,N-di(n-butyl)-N'-benzoylthiourea(HL~(1b))with I_2 or Br_2 in chloroform,leads to rapid oxidative addition to yield several geometric isomers of [Pt~(IV)(L-S,O)_2X_2](X = I,Br);the reactions can be monitored by ~(195)Pt NMR and UV-visible spectrophotometry.The products cis-[Pt~IV(L~(1a)-5,O)_2I_2] 6 and cis-[Pt~IV(L~(1a)-S,P)_2Br_2] 7,which have been isolated and structurally characterized,are the first-reported crystal structures of complexes of Pt(IV)with this class of ligand.Molecules of 6 pack such that the I-Pt-I axes are essentially aligned,with unusually close nearest-neighbour iodide contacts(3.553(1)A).These short I...I intermolecular interactions lead to infinite chains of weakly connected molecules in crystals of the compound.No such interactions are evident in the corresponding crystals of 7.Reaction of the Pt(II)complex of-N-propyl-N'-benzoylthiourea(H_2L~(2a))cis-trans-[Pt~II(H_2L~(2a)-5)_2Br_2] with Br_2 also results in oxidative addition,to yield trans-Pt~IV(H_2L~(2a)-S)_2Br_4 9.By contrast,treatment of cis-trans-[Pt~II(H_2L~(2a)-5)_2I_2] with I_2 does not lead to an oxidative addition product,yielding instead an interesting iodine inclusion compound of Pt~II,trans-[Pt~II(H_2L~(2a)-S)_2I_2]-I_2 8.In 8,short intermolecular I...I distances of 3.453(1)A between I_2 and coordinated iodide ions in trans-[Pt~II(H_2L~(2a)-S)_2I_2] molecules,result in infinite chains of weakly linked trans-[Pt~II(H_2L~(2a)-5)_2l2]...I_2 groups in the lattice.However,the empirically estimated bond order of 0.75 for the included I_2 molecules does not support the possible existence of discrete tetraiodide ions(I_4~(2-))in the lattice of compound 8.