A new approach to the synthesis of trinuclear gold(i) imidazolate complexes and their silver(i)-induced photoluminescence behavior.

New trinuclear gold(i) N-arylimidazolate cluster complexes have been synthesized from cationic [Au(CNR)2]+ isocyanide complexes and their structure and photoluminescence behavior have been compared with those of their 1-methylimidazolate counterpart. A drastic change in their photophysical properties was observed upon coordination of the Ag+ cation.

Selective formation of formamidines, carbodiimides and formimidates from isocyanide complexes of Mn(i) mediated by AgO.

The isocyanide ligands in complexes fac-[Mn(CNR)(bipy)(CO)3]+ are selectively transformed into formamidines, carbodiimides and formimidates upon nucleophilic addition of NH2Me or alkoxides and subsequent treatment with Ag2O, which promotes tautomerization or oxidation processes of the former carbene ligands.

Half-sandwich iron(ii) complexes with protic acyclic diaminocarbene ligands: synthesis, deprotonation and metalation reactions.

A variety of half-sandwich iron(ii) complexes with diprotic acyclic diaminocarbene ligands (pADCs) have been obtained by reaction of the cationic complexes [Fe(Cp)(CO)(CNR)] and [Fe(Cp)(CO)(CNR)] with methylamine, and their acid-base behaviour was studied, revealing an easy reversible deprotonation reaction of both N-H moieties of the carbene ligands. The deprotonation process is frequently followed by a nucleophilic attack of the nitrogen atom on a vicinal carbonyl or isocyanide ligand, affording the corresponding metallacycles. Metalation of one or two N-H groups of the pADC ligands can be accomplished by reaction of the carbene complexes with either [AuCl(PPh)] or [Ru(p-cym)Cl] in the presence of KOH or LiHMDS as deprotonating agents.

Template Synthesis, Metalation, and Self-Assembly of Protic Gold(I)/(NHC)2 Tectons Driven by Metallophilic Interactions.

A new protocol for the synthesis of protic bis(N-heterocyclic carbene) complexes of Au(I) by a stepwise metal-controlled coupling of isocyanide and propargylamine is described. They are used as tectons for the construction of supramolecular architectures through metalation and self-assembly. Notably a unique polymeric chain of Cu(I) with alternate Au(I) /bis(imidazolate) bridging scaffolds and strong unsupported Cu(I) -Cu(I) interactions has been generated, as well as a 28-metal-atoms cluster containing a nanopiece of Cu2 O trapped by peripheral Au(I) /bis(imidazolate) moieties.

Generating and trapping metalla-N-heterocyclic carbenes.

By means of a combined experimental and theoretical approach, the electronic features and chemical behavior of metalla-N-heterocyclic carbenes (MNHCs, N-heterocyclic carbenes containing a metal atom within the heterocyclic skeleton) have been established and compared with those of classical NHCs. MNHCs are strongly basic (proton affinity and pK(a) values around 290 kcal mol(-1) and 36, respectively) with a narrow singlet-triplet gap (around 23 kcal mol(-1)). MNHCs can be generated from the corresponding metalla-imidazolium salts and trapped by addition of transition-metal complexes affording the corresponding heterodimetallic dicarbene derivatives, which can serve as carbene transfer agents.

Synthesis and derivatization of highly-functionalized λ⁵-phospholes.

A variety of λ(5)-phosphole derivatives bearing up to three distinct peripheral functionalities have been prepared by regiospecific [3+2] cycloaddition reactions of the diphosphinoketenimine (PPh2)2C=C=NtBu (1) with electron-poor alkenes. Selective derivatization of the exocyclic functional groups, including formation of dimetallic complexes with a phosphole core, was subsequently accomplished.

Strong electron-donating metalla-N-heterocyclic carbenes.

By choosing the appropriate coupling reactions an isocyanide ligand in complex [Fe(Cp)(CO)(CNxylyl)2](+) is transformed into either a conventional NHC or into a metalla-N-heterocyclic carbene (MNHC), with the stretching frequencies of the CO and CNR ligands attached to the iron center demonstrating the stronger electron-donating ability of the metal-containing carbenes.

A three-component reaction involving isocyanide, phosphine and ketenimine functionalities.

A three-component reaction involving diphosphinoketenimines, isocyanides and water or ethanol leading to the formation of new five-membered azaphosphaheterocycles is described.

Synthesis and reactivity of diphosphine metal complexes bearing peripheral ketenimine functionalities.

Diphosphinoketenimine ligands (PPh(2))(2)C=C=NR (1a R = (t)Bu, 1b R = Ph) were reacted with different Cu(I), Ag(I), Au(I), Pd(II), Ru(II) and Mo(0) metal complexes bearing weakly coordinating ligands yielding a number of mono-, di-, and trimetallic species with the diphosphine acting as either chelate or bridging ligand. The reactivity of some of the new complexes toward water and MeLi was investigated. The mononuclear Pd(II) complex [PdCl(2){(PPh(2))(2)C=C=NPh}] (6b) is transformed into the diphosphinoamide complex [PdCl(2){(PPh(2))(2)CHC(=O)(NHPh)}] (12) by nucleophilic addition of water.

NHC-manganese(i) complexes as carbene transfer agents.

Tautomerization of coordinated azoles to their corresponding N-heterocyclic carbenes (NHCs) has been carried out by reaction of complexes fac-[Mn(L)(CO)(3)(dppe)](+) (L = N-phenylimidazole) and fac-[Mn(L)(CO)(3)(bipy)](+) (L = N-methylbenzimidazole, benzoxazole, benzothiazole) with KO(t)Bu and subsequent protonation of the azolyl intermediates with NH(4)PF(6). Several NHC-manganese(i) complexes bearing an N-H residue of general formula fac-[Mn(NHC)(CO)(3)(dppe)](+) and fac-[Mn(NHC)(CO)(3)(bipy)](+) have been tested as carbene transfer agents to the gold fragments [Au(L)](+) (L = PPh(3), CNPh, CNXylyl), allowing isolation or spectroscopic detection of various Mn(i)/Au(i) heterometallic intermediates containing azolyl bridging ligands, which liberate the gold(i) carbene complexes [Au(NHC)(L)](+) by means of acid hydrolysis. By contrast, when using the silver(i) fragment [Ag(PPh(3))](+) as carbene acceptor no transmetallation process occurred but instead inverse tautomerization of the NHC to the corresponding imidazole ligand was observed.

D(+)-pi-A(-) charge-transfer molecules based on tricyanoquinodimethane and diphosphine metal complexes.

A new family of D (+)-pi-A (-) chromophores in which the donor group is an organometallic complex and the acceptor group a tricyanoquinodimethane moiety has been synthesized by the reaction of diphosphinomethanide transition-metal complexes and 7,7',8,8'-tetracyanoquinodimethane.

New approach to sulfonated diphosphine complexes: synthesis and amphoteric behaviour of zwitterionic [Mn+(CO4{(PPh2)2C(H)SO3-}].

Oxidation of the thioketone residue in the complex [Mn(CO)4{(PPh2)2C=S}]+ (2) with hydrogen peroxide affords the sulfonate derivative [Mn(CO)4{(PPh2)2C(H)SO3}] (3), which shows amphoteric behaviour in reversible acid-base processes, and is easily chlorinated to give [Mn(CO)4{(PPh2)2C(Cl)SO3}] (8).

Generation of N-heterocyclic carbenes by metal-mediated coupling of propargylamine and isocyanides.

A new method for the synthesis of heterocyclic carbenes of imidazol-2-ylidene and oxazol-2-ylidene types implying a cycloaddition reaction of propargylamine and propargylic alcohol, respectively, to coordinated isocyanide ligands has been developed.

Diphosphanylketenimines: new reagents for the synthesis of unique phosphorus heterocycles.

Two consecutive [3+2] cycloaddition reactions of the diphosphanylketenimine (PPh(2))(2)C[double bond]C[double bond]NPh (3), involving the phosphanyl groups, with two equivalents of the electron-poor alkynes dimethyl acetylenedicarboxylate or methyl acetylenecarboxylate give rise to the formation of the bicyclic 1 lambda(5),3 lambda(5)-diphospholes 5 a,b, which contain a phosphorane unit with five carbon substituents attached to the phosphorus center. Compound 3 undergoes cyclodimerization by crystallization, affording the unsymmetrical dimer 6, which is converted back to 3 by heating in toluene. Compound 6 can be oxidized stepwise on the three trivalent phosphorus atoms by treatment with H(2)O(2) affording 7, 9, and the transient species 10, which are transformed into their corresponding ketenimine monomers either spontaneously (10) or by heating in toluene (7, 9).