A series of thermally stable N-heterocyclic copper-chalcogenolate complexes of the general formula [(IPr)Cu-ESiMe3] (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene; E = S, Se, Te) have been prepared from [(IPr)CuOAc] and E(SiMe3)2 at low temperature. The reaction of [(IPr)Cu-SSiMe3] with mercuric(II) acetate affords the heterometallic [{(IPr)CuS}2Hg] complex containing two (IPr)Cu-S(-) fragments to a central Hg(II).

We explore the effect of π-π interactions in the complexes of mercury halides containing the N-(naphthyl)-2pyrazine carboxamide ligand (L1) in the coordination geometry of the central metal. Results show molecular packing features have a dramatic effect on coordination geometries and that the π-π stacking interaction affects the geometry around the mercury.

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A bidentate nitrogen-donor ligand with an appended phenol group, CHNCH[double bond, length as m-dash]N-2-CHOH, H(L1) was treated with a palladium cycloneophyl complex [Pd(CHCMeCH)(COD)], with both Pd-aryl and Pd-alkyl bonds, to give a Pd-alkyl complex, [Pd(CHCMeCH)(κ-N,N',O-OCHN[double bond, length as m-dash]CH(2-CHN))], 1. The cleavage of the Pd-aryl bond and the deprotonation of the ligand phenol to afford a bound aryloxide, indicates facile Pd-aryl bond protonolysis. Deuterium labelling experiments confirmed that the ligand phenol promotes protonolysis and that the reverse, aryl C-H activation, occurs under very mild reaction conditions (within 10 min at room temperature). An unusual isomerization of the Pd-alkyl complex 1 to a Pd-aryl complex, [Pd(CH(2-t-Bu))(κ-N,N',O-OCHN[double bond, length as m-dash]CH(2-CHN))], 2, was observed to give an equilibrium with [2]/[1] = 9 after 5 days in methanol. The isomerization requires that both aryl C-H activation and Pd-alkyl protonolysis steps occur. The very large KIE value (k/k = ca. 40) for isomerization of 1 to 2, suggests a concerted S2-type mechanism for the Pd-alkyl protonolysis step.

A ferrocene-based dithiol 1,1'-[fc(C{O}OCH2CH2SH)2] has been prepared and treated with a Ag(I) salt to form the stable dithiolate compound [fc(C{O}OCH2CH2SAg)2]n (fc=[Fe(η(5)-C5H4)2]). This is used as a reagent for the preparation of the nanocluster [Ag74S19(dppp)6(fc(C{O}OCH2CH2S)2)18] which was obtained in good yield (dppp=1,3-bis(diphenylphosphino)propane).

The ligand N­(CH2-2-C5H4N)2(CH2CH2CH2OH), L1, reacted with [Pd­(CH2CMe2C6H4)­(COD)] to give a new fluxional “cycloneophyl” organopalladium complex [Pd­(CH2CMe2C6H4)­(κ2-L1)], 1, which on attempted recrystallization from THF gave the monodentate carbonate complex [Pd­(CO3)­(κ3-L1)], 2. Complex 2 was prepared in designed syntheses by reaction of [PdCl­(κ3-L1)]+ with silver carbonate or by reaction of [Pd­(OH)­(κ3-L1)]+ with CO2. Complex 1 reacted with aqueous CO2 to give the cationic neophylpalladium complex [Pd­(CH2CMe2C6H5)­(κ3-L1)]+(HCO3)−, 6. Complex 6 reacts with hydrogen peroxide to give complex 2 with release of a mixture of organic products, the major one being 2-phenyl-2-butanol, PB. The formation of PB involves a neophyl rearrangement with the unprecedented preference for methyl over phenyl migration. A mechanistic basis for this unexpected reaction is proposed, involving β-carbon elimination at a palladium­(IV) center.

As a part of efforts to prepare new "metallachalcogenolate" precursors and develop their chemistry for the formation of ternary mixed-metal chalcogenide nanoclusters, two sets of thermally stable, N-heterocyclic carbene metal-chalcogenolate complexes of the general formula [(IPr)Ag-ESiMe3] (IPr=1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene; E=S, 1; Se, 2) and [(iPr2-bimy)Cu-ESiMe3]2 (iPr2-bimy=1,3-diisopropylbenzimidazolin-2-ylidene; E=S, 4; Se, 5) are reported. These are prepared from the reaction between the corresponding carbene metal acetate, [(IPr)AgOAc] and [(iPr-bimy)CuOAc] respectively, and E(SiMe3 )2 at low temperature. The reaction of [(IPr)Ag-ESiMe3] 1 with mercury(II) acetate affords the heterometallic complex [{(IPr)AgS}2Hg] 3 containing two (IPr)Ag-S(-) fragments bonded to a central Hg(II), representing a mixed mercury-silver sulfide complex. The reaction of [(iPr2-bimy)Cu-SSiMe3]2, which contains a smaller N-heterocyclic-carbene, with mercuric(II) acetate affords the high nuclearity cluster, [(iPr2-bimy)6Cu10S8Hg3]6. The new N-heterocyclic carbene metal-chalcogenolate complexes 1, 2, 4, 5 and the ternary mixed-metal chalcogenolate complex 3 and cluster 6 have been characterized by multinuclear NMR spectroscopy ((1)H and (13)C), elemental analysis and single-crystal X-ray diffraction.

A new route to cycloneophylplatinum­(II) complexes is reported and the selectivity of protonolysis of the platinum–aryl and −alkyl bonds has been determined. Reaction of [PtCl2(SMe2)2] with neophylmagnesium chloride gives the binuclear cycloneophylplatinum­(II) complex [Pt2(CH2CMe2C6H4)2(μ-SMe2)2], 1, which is shown to exist as a mixture of syn and anti isomers. Complex 1 reacts reversibly with SMe2 to give [Pt­(CH2CMe2C6H4)­(SMe2)2], 2, and irreversibly with bidentate ligands NN = 3,4,7,8-tetramethyl-1,10-phenanthroline (phen*) or 4,4′-di-t-butyl-2,2’bipyridine (bubipy) to give the corresponding complexes [Pt­(CH2CMe2C6H4)­(phen*)], 3, and [Pt­(CH2CMe2C6H4)­(bubipy)], 4, respectively. Complex 2 reacts with HCl initially by cleavage of the aryl–platinum bond to give mostly trans-[PtCl­(CH2CMe2Ph)­(SMe2)2], which then rearranges to an equilibrium mixture with trans-[PtCl­(C6H4-2-t-Bu)­(SMe2)2], while 3 and 4 react to give [PtCl­(CH2CMe2Ph)­(phen*)] and [PtCl­(CH2CMe2Ph)­(bubipy)], which do not undergo the isomerization reaction. The protonolysis reactions occur by way of a platinum­(IV) hydride complex in each case, and the unusual reactivity of complex 2 is attributed to the ease of dissociation of the Me2S ligands.