Organometallic Complexes of Platinum, Palladium and Mercury

Tennent, Norman H (1974) Organometallic Complexes of Platinum, Palladium and Mercury. PhD thesis, University of Glasgow.

Abstract

A synthetic route to a series of 2-(arylazo)arylmercury compounds has been developed in the hope of providing a good transfer reagent for the high-yield synthesis of other 2-(arylazo)aryl metal complexes. Reaction of a series of sodium 2-(arylazo)arylsulphinates (which are prepared in two stages from bis(2-nitroaryl)disulphides) with mercuric chloride resulted in formation of 2-(arylazo)arylmercuric chloride complexes. The range of known substituted 2-(arylazo)arylsulphinates has been extended by this work and their reaction with mercuric chloride is a new development of the Peter's Reaction. Derivatives with a variety of ring substituents on both rings have been prepared by this method. A combination of IR and NMR spectroscopic investigations established the substitution patterns involved and demonstrated a retention of specific substitution patterns throughout the synthetic route. Those compounds were found to be useful reagents in the synthesis of other 2-(arylazo)aryl metal complexes. Reaction with PdCl2 gave quantitative yields of the ring-substituted dimers, ((azb)PdCl)2, although with PtCl2 decomposition occurred. The formation of (PhN:NC6H4)M(PEt3)2Cl (M=Pt or Pd) was achieved using (PhN:NC6H4)2Hg and was also more successful with palladium than platinum. Transfer of the 2-(phenylazo)phenyl group from mercury to nickel and manganese has also been established by reactions with (h5-C5-H5)2Ni and Mn(CO)5Cl. These reagents produced high yields of (azb)Ni(h5-C5H5) and (azb)Mn(CO)4, respectively, when treated with the 2-(phenylazo)phenyl mercurial. Cleavage of the metal-carbon bond of the 2-(arylazo)arylmercuric chloride complexes occurred in several reactions. The organic products were in many cases new and in some cases are known to be difficult to prepare by other means. Ready Hg-C bond cleavage by halogens produced the corresponding 2-(arylazo)arylhalides in high yield while reaction of (PhN:NC6H4)HgCl with nitrosyl chloride produced a nitrogen-containing heterocycle; 2-phenylbenzotriazole-l-oxide. Another organic heterocycle, IH-2phenyl-3indazolone, was formed under mild conditions by carbonylation of ((azb)PdCl)2. All the syntheses using these mercurials have the potential for specific and predictable ring substitution of the products. This is not afforded by many other routes to these compounds and indicates the value of 2-(arylazo)arylmercurials as synthetic reagents. The 1H NMR of trans(PhN:NC6H4)Pt(PMePh2)Cl, prepared as part of the study of 2-(arylazo)aryl metal complexes, was found to show line broadening. This has been investigated by variable temperature studies and arises from rapid phosphine exchange. The system (Ph2MeP)2PtX2/Ph2MeP (X=Cl, Br or I) also shows phosphine exchange broadening and it too has been examined. The conclusions from these observations have been combined with reported examples of phosphine exchange and an assessment made of the importance of the various factors governing this process. The complex (azb)Pt(CO)Cl, prepared by carbon monoxide bridge-cleavage of ((azb)PtCl)2, was found to undergo CO displacement with a variety of Lewis Bases. In an attempt to gain further insight into carbonyl insertion reactions, several other mononuclear platinum carbonyl complexes have been prepared and investigated. The interaction of (PhMe2P)Pt(CO)X2 (X=Cl, Br, or I) and (R5P)Pt(CO)Br(Ph) (R3P=Et3P or PhMe2P) with a wide variety of reagents showed that the extent of carbon monoxide displacement compared to insertion is great, although Ph4Sn and (o-tolyl)2Hg did produce insertion with (PhMe2P)Pt(CO)Cl2. The displacement reaction, however, predominated and in the reaction of bromine with (Et3P)Pt(CO)Br(Ph) a new platinum(lV) bridged complex, ((Et3P)PtBr3Ph)2, was formed. A rationalisation of carbonyl insertion and displacement reactions has been proposed.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Organic chemistry, Inorganic chemistry
• Date of Award: 1974
• Depositing User: Enlighten Team
• Unique ID: glathesis:1974-78666
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 28 Feb 2020 12:09
• Last Modified: 28 Feb 2020 12:09
• URI: https://theses.gla.ac.uk/id/eprint/78666