Role of Bis(phosphinimino)methanides as Universal Ligands in the Coordination Sphere of Metals across the Periodic Table

The coordination chemistry of bis(phosphinimino)methanide ligands is widespread and accompanies a large number of metal ions in the periodic table ranging from lithium to neptunium. This unique class of ligand systems show copious coordination chemistry with the main-group, transition, rare-earth, and actinide metals and are considered to be among the most attractive ligand systems to researchers. The bis(phosphinimino)methanide metal complexes offer an extensive range of applications in various fields and have been demonstrated as one of the universal ligand systems to stabilize the metal ions in not only their usual but also their unusual oxidation states. The main-group and transition metal chemistry using bis(phosphinimino)methanides as ligands was last updated almost a decade ago. In this review, we provide a comprehensive overview of various state-of-the-art bis(phosphinimino)methanide-supported metal complexes by dealing with their synthesis, characterization, reactivity, and catalytic studies which were not included in the last critical reviews.

(Iminophosphoranyl)(thiophosphoranyl)methane rare-earth borohydride complexes: synthesis, structures and polymerization catalysis

The {CH(PPh₂NSiMe₃)(PPh₂S)}⁻ligand has been used for the synthesis of divalent and trivalent rare-earth borohydride complexes. These compounds enable the ring-opening polymerization (ROP) of ε-caprolactone (CL) and trimethylene carbonate (TMC).

A cascade reaction: ring-opening insertion of dioxaphospholane into lutetium alkyl bonds

Although an organolutetium complex of a new dioxaphospholane-substituted carbazole-based pincer ligand appears immune to cyclometalation, an unusual ring-opening insertion reaction was observed.

Titanium imido complexes stabilised by bis(iminophosphoranyl)methanide ligands: the influence of N-substituents on solution dynamics and reactivity

The synthesis, structural study and assessment in catalytic hydroamination of Ti imido complexes with bis(iminophosphoranyl)methanide ligands are reported.

Stable cyclic carbenes and related species beyond diaminocarbenes

The success of homogeneous catalysis can be attributed largely to the development of a diverse range of ligand frameworks that have been used to tune the behavior of various systems. Spectacular results in this area have been achieved using cyclic diaminocarbenes (NHCs) as a result of their strong σ-donor properties. Although it is possible to cursorily tune the structure of NHCs, any diversity is still far from matching their phosphorus-based counterparts, which is one of the great strengths of the latter. A variety of stable acyclic carbenes are known, but they are either reluctant to bind metals or they give rise to fragile metal complexes. During the last five years, new types of stable cyclic carbenes, as well as related carbon-based ligands (which are not NHCs), and which feature even stronger σ-donor properties have been developed. Their synthesis and characterization as well as the stability, electronic properties, coordination behavior, and catalytic activity of the ensuing complexes are discussed, and comparisons with their NHC cousins are made.

Gold-catalyzed intermolecular Markovnikov hydroamination of allenes with secondary amines

A cationic (CAAC)gold(I) complex promotes the addition of all types of nontertiary amines to a variety of allenes, affording allylic amines in good to excellent yields; the amino fragment always adds to the less substituted terminus of the CCC skeleton.

Synthesis of a simplified version of stable bulky and rigid cyclic (alkyl)(amino)carbenes, and catalytic activity of the ensuing gold(I) complex in the three-component preparation of 1,2-dihydroquinoline derivatives

A 95/5 mixture of cis and trans 2,4-dimethyl-3-cyclohexenecarboxaldehyde (trivertal), a common fragrance and flavor material produced in bulk quantities, serves as the precursor for the synthesis of a stable spirocyclic (alkyl)(amino)carbene, in which the 2-methyl-substituted cyclohexenyl group provides steric protection to an ensuing metal. The efficiency of this carbene as ligand for transition metal based catalysts is first illustrated by the gold(I) catalyzed hydroamination of internal alkynes with secondary dialkyl amines, a process with little precedent. The feasibility of this reaction allows for significantly enlarging the scope of the one-pot three-component synthesis of 1,2-dihydroquinoline derivatives, and related nitrogen-containing heterocycles. Indeed, two different alkynes were used, which include an internal alkyne for the first step.

A cationic gold(I) complex as a general catalyst for the intermolecular hydroamination of alkynes: application to the one-pot synthesis of allenes from two alkynes and a sacrificial amine

Two very distinct chemical reactions, yet a single catalyst: A gold complex promotes the formation of tertiary enamines from a variety of terminal and internal alkynes. Subsequent addition of a terminal alkyne to the reaction mixture affords allenes (see scheme).