U045800.pdf (5.89 MB)
Download file

The synthesis and reactivity of four-membered platinacycles containing S and/or N bonded ligands.

Download (5.89 MB)
posted on 19.11.2015, 08:46 by Mark Richard. Moore
Chapter 1 reviews the literature concerning transition metal n3-oxodimethylenemethane-(metallacyclobutan-3-one), metallathietane-3-oxide, metallathietane-3,3-dioxide and ureylene complexes. The review also briefly discusses the use of the oxodimethylenemethane metal fragment in organic synthesis. The preparation and characterisation of platinathiazetidine-3-imine complexes [Pt{lcub}NPhC(=NPh)S{rcub}L2] are described in Chapter 2. X-ray crystallographic studies on two of these derivatives (L = PPh3 or PMePh2) revealed the near-planarity of the four-membered ring. Both triphenylphosphine ligands in [Pt{lcub}NPhC(=NPh)S{rcub} (PPh3)2] are easily displaced by more basic phosphines or a chelating phosphine, and one is displaced by t-butyl isocyanide to give a monosubstituted derivative. The complex reacts with carbon monoxide to give a ring expansion product. Attempted ring expansions with small cumulenes were unsuccessful. Treatment of [Rh(C1)(CO)(dppm)]2 with the dianion of N,N'-diphenylthiourea led to formation of the "A"-frame complex [Rh2(micro-S)(CO)2(dppm)2]. Chapter 3 describes the synthesis and characterisation of platinathiadiazetidine-3,3-dioxide complexes of the type [Pt{lcub}NRS(O)2NR{rcub}L2] (R = H or Ph). X-ray crystallographic studies on two of the derivatives (R = H, L = PMePh2; R = Ph, L2 = COD) showed the four-membered rings to be entirely flat, the molecules possessing a two-fold rotation axis about the platinum-sulphur vector. Efforts to insert small cumulene molecules into the N-H bonds of [Pt{lcub}NHS(O)2NH{rcub}(PMePh2)2] are described. Treatment of this complex with phenylacetylene gave trans-[Pt(C=CPh)2(PMePh2)2], whereas with dimethyl acetylenedicarboxylate the complex [Pt{lcub}C(CO2Me)=C(CO2Me)NHS(O)2NH{rcub} (PMePh2)2] was obtained, formally derived from insertion of the acetylene into a platinum-nitrogen bond. An X-ray crystallographic study revealed that the six-membered ring in this complex adopted a "pseudo-boat" conformation. Reaction of [PtC12(COD)] with sulphamide and excess silver(I) oxide in refluxing dichloromethane, followed by treatment of the filtrate from this reaction with an excess of t-butyl isocyanide afforded a complex which was formulated as [Pt{lcub}C(=NBut)NHS(O)2NHC(=NBut){rcub}(CNBut)2]. One phosphine ligand in [Pt{lcub}NPhS(O)2NPh)(PPh3)2] can be replaced by t-butyl isocyanide to give a monosubstituted complex. The final Chapter briefly describes attempts to synthesise further Pt(II) complexes from cis-[PtC12L2] and ligands possessing "activated" protons. The interaction of cis-[PtC12(PPh3)2] with some p-tosylhydrazones in the presence of silver(I) oxide is investigated, and liquid ammonia as a synthetic reagent was also used in some of these reactions instead of silver(I) oxide. The complexes cis-[Pt{lcub}NHS(O)2C6H4-P-R{rcub}2L2] (R = H or Me) are obtained on reaction of cis-[PtC12L2] with the appropriate sulphon-amide and an excess of silver(I) oxide in dichloromethane. The reaction of cis-[PtC12(PPh3)2] with urea and silver(I) oxide in dichloromethane, or with urea in liquid ammonia, was investigated.


Date of award


Author affiliation


Awarding institution

University of Leicester

Qualification level


Qualification name




Usage metrics