Geoffrey H. D. Royston

Electronic effects in the reactions of coordinated isonitriles; bis-carbene complexes of platinum(II) and palladium(II)

Abstract The reactions of complexes of the type cis-[PtCl2(RNC)(PR′3)] (R = p-CH3OC6H4, C6H5 or p-NO2C6H4; PR′3 = PPh3, PEtPh2, PEt2Ph or PEt3) with ethanol have been investigated. Reaction of the coordinated isonitrile with ethanol to give an ethoxy-carbene ligand is quickest for R = p-NO2C6H4 and slowest for R= p-MeOC6H4 consistent with nucleophilic attack at isonitrile carbon by ethanol. Variation of PR′3 has little effect on the reaction rate. The derived carbene complexes are characterised together with the bis-carbene complexes cis-[MCl2{C(OEt)NHp-NO2C6H4}2] (M = Pt or Pd) obtained by reaction of the cis-[MCl2(p-NO2C6H4NC)2] compounds with ethanol.

Metallation of a phenyl group in a platinum(II) carbene complex during oxidation to platinum(IV)

Abstract Reaction of chlorine with cis -[PtCl 2 {C(NHR)(NHR′) }PEt 3 ] and trans -[PtCl{C(NHR)(NHR′)}(PEt 3 ) 2 ]ClO 4 gives analogous platinum(IV) carbene complexes when R = R′ = Me; but when R = Me or Et and R′ = Ph, 2-metallation and 4-chlorine substitution of the phenyl group occurs, shown by the X-ray structure of [PtCl 2 {C(Cl·C 6 H 3 NH)(NHMe)}(PEt 3 ) 2 ]ClO 4 .

Preparation, structure, and redox properties of isocyanide complexes of molybdenum(0) and tungsten(0)

The complexes trans-[M(CNR)2(dppe)2](A)(M = Mo or W; R = Me, But, Ph, C6H4Me-4, C6H4Cl-4, C6H3Cl2-2,6, or C6H4OMe-4; dppe = Ph2PCH2CH2PPh2) have been prepared. They have low ν(NC) values which are discussed in terms of their electronic structure. The electrochemical properties of the complexes are described and correlations are drawn between their redox potentials and the electronic properties of the isocyanide ligands.

Formation of carbyne-like ligands by the protonation of isonitriles ligating electron-rich metal centres; X-ray structure of trans-[Mo(CNMe)2(Ph2PCH2CH2PPh2)]

The compounds trans-[M(CNR)2(dpe)2](M = Mo or W; R = Me, But or aryl; dpe = Ph2PCH2CH2-PPh2) have been prepared, and they can be protonated at one or both nitrogen atoms giving carbyne-like ligands, but alkylated at only one; X-ray structure analysis shows that the CNMe angle in trans-[Mo(CNMe)2(dpe)2] is 156(1)°.

Isonitrile complexes of osmium and their reactions to give hydride, amine, and carbene complexes

Uncharged and cationic isonitrile complexes of osmium of the types [OsCl2(RNC)2(PR13)2], [OsCl2(RNC)(PMe2Ph)3], [OsBr2(MeNC)4], [OsCl2(RNC)(PR13)3]ClO4, [OsCl2(RNC)2(PR13)2]ClO4, [OsCl(RNC)2(PR13)3]ClO4, and [Os(MeNC)6](ClO4)2(R = Me, Ph, p-MeOC6H4, or p-NO2C6H4; PR13= PMe2Ph, PEt2Ph, PBun2Ph, or PEt3) and the carbonyl–isonitrile complexes [OsCl2(CO)(PhNC)(PEt3)2], [OsCl(CO)(RNC)(PR13)3]ClO4(R = Me or Ph; PR13= PMe2Ph or PEt3) and [OsCl2(CO)(PhNC)(PEt3)2]ClO4 have been prepared. Some of the above compounds react with sodium borohydride or appropriate primary amines to give the compounds [OsHCl-(PhNC)(PMe2Ph)3] and [OsCl2(R2NH2)(PhNC)(PEt3)2](R2= Me or Et), the bis-carbene complex [Os(MeNC)4{C(NHMe)2}2](ClO4)2 and the tris-carbene complex [Os(MeNC)3{C(NHMe)2}3](ClO4)2. A few ruthenium complexes of the type [RuCl2(RNC)2(PR13)2](PR13= PMe2Ph, PPrn2Ph, or PBunPh) were also prepared and did not react with amines or alcohols. 1H N.m.r. and i.r. data are used to assign the configuration of the above compounds.The reactivity towards nucleophiles of ligating isonitrile correlates with the magnitude of the increase of its NC stretching frequency on co-ordination.

Metallation of phenyl group induced by oxidation: carbene complexes of platinum(IV)

The reactions of dichlorine with the complexes cis-[PtCl2{C(NHR1)(NHR2)}(PEt3)], cis-[PtCl2{C(OR3)(NHR2)}-(PR43)] and trans-[PtCl{C(NHR1)(NHR2)}(PEt3)2][ClO4](R12= Me or Et; R12= Me, Ph, 2,4-Cl2C6H3, 2,6-Cl2C6H3, 2-ClC6H4; R3= Me or Et; PR43= PEt3 or PPh3) have been examined. Where R1= R2= Me, the platinum(IV)–carbene complexes [PtCl4{C(NHMe)2}(PEt3)] and [PtCl3{C(NHMe)2}(PEt3)2][ClO4] result, but where R1= Me or Et and R2= Ph, 2-ClC6H4, or 4-ClC6H4; 2-metallation (and chlorine substitution in some cases) of the phenyl group occurs, giving the complexes [[graphic omitted]H3Cl-4)}(PR43)], [[graphic omitted]H3Cl-4)}(PEt3)2][ClO4], and [[graphic omitted]H3Cl-2)}(PEt3)2][ClO4]. The i.r. and n.m.r. spectra of these complexes and possible reaction mechanisms are discussed. Treatment of trans-[PtBr{C(NHMe)2}(PEt3)2][ClO4] and trans-[PtBr{C(NHEt)(NHPh)}(PEt3)2][ClO4] with dibromine gave trans-[PtBr4(PEt3)2] as the only isolable product.