208538-96-9Relevant academic research and scientific papers
Insertion reactions of platinum(II) ureylene complexes
Dinger, Maarten B.,Henderson, William
, p. 1763 - 1773 (2007/10/03)
The reactivity of platinum(II) ureylene complexes towards various unsaturated molecules has been investigated. The complexes [Pt{NPhC(O)NPh}(cod)] 1a (cod = cycloocta-1,5-diene) and [Pt{NMeC(O)NPh}(cod)] 1b readily inserted phenyl isocyanate to give [Pt{NPhC(O)NPhC(O)NPh)}(cod)] and [Pt{NPhC(O)NMeC(O)NPh)}(cod)] respectively, with insertion taking place solely at the Pt-NMe linkage for the latter. When 1b was treated with the isoelectronic diphenyl carbodiimide the product was characterised as [Pt{NPhC(O)NMeC(O)NPh}(cod)], presumably the result of hydrolysis. The biureto ligand in the latter was readily liberated by hydrochloric acid to give N′-methyl-N,N″-diphenylbiuret. Complex 1b was also treated with various disubstituted acetylenes. Dimethyl acetylenedicarboxylate rapidly inserted into the Pt-NMe bond to give [Pt{C(CO2Me)=C(CO2Me)NMeC(O)NPh}(cod)]. Compound 1b failed to react with diphenylacetylene, and was decomposed by methyl propiolate. Reaction of the more robust platinum ureylene [Pt{NMeC(O)NPh}(PPh3)2] with methyl propiolate displaced the urea dianion to give the diacetylide complex [Pt{C≡CC(O)OMe}2(PPh3)2]. The compound [Pt(NMeC(O)NPh)(PPh3)2] was also treated with PhNSO and again the ureylene ligand was displaced to give the dimeric platinum sulfito complex [{Pt(SO3)(PPh3)2} 2]·2PhNHC(O)NHMe. The crystal structure of the 2CHCl3 solvate shows the complex to contain cocrystallised N-methyl-N′-phenylurea, hydrogen bonded from the NH moieties to the S(O)2 groups. The compound presumably arises from hydrolysis of N-sulfinylaniline (or an intermediate insertion product thereof), and was also the only product characterised from the reaction of [Pt{NMeC(O)NPh}(PPh3)2] with sulfur dioxide. One of the chloroforms of crystallisation is also hydrogen bonded to the S(O)2. The complex [Pt{NMeC(O)NPh}(PPh3)2] rapidly inserted carbon disulfide to give [Pt{S2CNMeC(O)NPh}(PPh3)2] fully characterised by a single-crystal X-ray study. The complex contains a highly puckered six-membered ring, with the fold angle between the least-squares planes drawn through the co-ordination plane of the platinum and the remainder of the metallacycle being 56.8(1)°. In solution the compound slowly decomposes by loss of phenyl isocyanate to give [Pt(S2C=NMe)(PPh3)2], also fully characterised by an X-ray crystallographic study. All the complexes reported have been subjected to extensive 1H, 13C and (where appropriate) 31P NMR analysis. Further data from electrospray mass spectrometry, IR spectroscopy and elemental analysis are also given.
