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Metal-ligand cooperative iron complexes of the type [Fe(Cp*)(PR2NPh2)(MeCN)]PF6 (R = Cy, Ph) were synthesized and characterized. Both derivatives were active toward the intramolecular hydroamination of 2-ethynylaniline and hydroalkoxylation of 2-ethynylbenzyl alcohol. In the latter case, only the six-membered endo heterocycle isochromene was observed, which suggests that the alkyne is activated by a vinylidene mechanism. The reaction of [Fe(Cp*)(PCy2NPh2)(MeCN)]PF6 with phenylacetylene indeed afforded a complex that was characterized as a vinylidene, which implicates an analogous intermediate in the hydrofunctionalization mechanism.

A dimer with two PdII–Me fragments is stabilized by the bridging coordination of the supporting 1-azaallyl/phosphine ligand. Heating the complex results in C(sp3)–C(sp3) bond formation and the release of ethane. Two different palladium products are generated, each with distinct coordination modes of the 1-azaallyl/phosphine ligand.

Two phosphine-imine ligands were synthesized in which the heteroatoms were connected by an ethyl (1a) or a propyl (1b) linker. Both ligands were reacted with PdCl(Me)(COD), which gave the square planar complexes PdCl(Me)(κ2-P,N-1a) (2a) and PdCl(Me)(κ2-P,N-1b) (2b). Both complexes were treated with base in pyridine in an effort to prepare phosphine 1-azaallyl complexes of the type Pd(Me)(κ2-P,N-L)(py). Deprotonation of 2a gave an intractable mixture of products. In contrast, deprotonation of 2b afforded a new product 4b. However, the site of deprotonation was the methylene adjacent to the phosphine rather than Cα to the imine carbon, deprotonation of which would have afforded a 1-azaallyl moiety.

The synthesis of three new NiCl(allyl/cinnamyl)(NHC) complexes, containing a bifunctional NHC (N-heterocyclic carbene) ligand is described. Two different NHCs were utilized that contain a secondary amine (HNR; R=t-Bu or Mes) moiety on one of the N-imidazolylidene arms. Complexes with allyl (2 a) and cinnamyl (3 a and 3 b) were each crystallographically characterized and η3-allyl and κ1-C NHC ligand coordination modes were found in the solid-state. In the solution-state, each of the ligands shows highly fluxional behaviour. Halide substitution of the chloro ligand for iodo effectively slows the ligand dynamics and permits solution-state characterization that is in agreement with the solid-state structures. The complexes react with oxygen to ultimately oxidize the allyl or cinnamyl ligands to acrolein (AC) or cinnamaldehyde (CA) and phenyl vinyl ketone (PVK), respectively. The bifunctional nature of the NHC has limited influence on oxidation reactivity, but preliminary evidence suggests it plays a role in the stability of the nickel oxidation products.

[Ru(Cp)(PPh2NBn2)(MeCN)]PF6 (1; PPh2NBn2 = 1,5-benzyl-3,7-phenyl-1,5-diaza-3,7-diphosphacyclooctane) and [Ru(Cp)(dppp)(MeCN)]PF6 (2; dppp = 1,3-bis(diphenylphosphino)propane) are both active toward the acceptorless dehydrogenation of benzylamine (BnNH2) and N-heterocycles. The two catalysts have similar activities but different selectivities for dehydrogenation products. Independent synthesis of a [Ru(Cp)(PPh2NBn2)(NH2Bn)]PF6 adduct (3) reveals the presence of a hydrogen bond between the bound amine and the pendent base of the PPh2NBn2 ligand. Preliminary mechanistic studies reveal that the benzylamine adduct is not an on-cycle catalyst intermediate.

The chemistry of a palladium(II) complex containing both an alkyl– and an aryl–palladium bond is reported. The reaction of [Pd(CH2CMe2C6H4)(MesN═CHCH═NMes)] with bromine or iodine leads to reductive elimination of 1,1-dimethylcyclobutabenzene with formation of [PdX2(MesN═CHCH═NMes)] (X = Br, I). However, the reaction with hydrogen peroxide gives [Pd(CH2CMe2C6H4O)(MesN═CHCH═NMes)] by overall oxygen atom insertion into the aryl–palladium rather than the alkyl–palladium bond. This complex [Pd(CH2CMe2C6H4O)(MesN═CHCH═NMes)] reacts with bromine, iodine, or hydrogen peroxide to give 3,3-dimethyl-2,3-dihydrobenzofuran and the corresponding complex [PdX2(MesN═CHCH═NMes)]. The mechanisms of reaction and basis for selectivity are discussed. The results support the view that oxygen atom insertion is a mechanistically viable pathway for selective catalytic oxidation of hydrocarbons by the green oxidant hydrogen peroxide.

The combination of a palladium(ii) precursor with a diimine-phenol ligand and an oxidant (H2O2 or O2) under different conditions has, serendipitously, given both a molecular square and a molecular tetrahedron by self-assembly of building blocks comprising palladium(ii) centres coordinated to the oxidised forms of the ligand.