Bimetallic lithium aluminates and neutral aluminum counterparts are compared as catalysts in hydroboration reactions with aldehydes, ketones, imines and alkynes. Possessing Li–Al cooperativity, ate catalysts are found to be generally superior. Catalytic activity is also influenced by the ligand set, alkyl and/or amido. Devoid of an Al−H bond, iBu2Al(TMP) operates as a masked hydride reducing benzophenone through a β‐Η transfer process. This catalyst library therefore provides an entry point into the future design of Al catalysts targeting substrate specific transformations.

Introduced here is a new type of strongly donating N‐heterocyclic boryloxy (NHBO) ligand, [(HCDippN)2BO]− (Dipp=2,6‐diisopropylphenyl), which is isoelectronic with the well‐known N‐heterocyclic iminato (NHI) donor class. This 1,3,2‐diazaborole functionalized oxy ligand has been used to stabilize the first acyclic two‐coordinate dioxysilylene and its Ge, Sn, and Pb congeners, thereby presenting the first complete series of heavier group 14 dioxycarbene analogues. All four compounds have been characterized by X‐ray crystallography and density‐functional theory, enabling analysis of periodic trends: the potential for the [(HCDippN)2BO]− ligand to subtly vary its electronic‐donor capabilities is revealed by snapshots showing the gradual evolution of arene π coordination on going from Si to Pb.

We introduce a new type of strongly donating Nheterocyclic boryloxy (NHBO) ligand, [(HCDippN)2BO] − , which is isoelectronic with the well-known N-heterocyclic iminato (NHI) donor class. This 1,3,2-diazaborole functionalized oxy ligand can be employed to stabilize the first acyclic two-coordinate dioxysilylene and its Ge, Sn and Pb congeners, thereby presenting the first complete series of heavier group 14 dioxycarbene analogues. All four compounds have been characterized by X-ray crystallography and Density Functional Theory (DFT), enabling analysis of periodic trends: the potential for the [(HCDippN)2BO] − ligand to subtly vary its electronic donor capabilities is revealed via snapshots revealing gradual evolution of arene π-coordination on going from Si to Pb.

Herein the sodium alkylmagnesium amide [Na4Mg2(TMP)6(nBu)2] (TMP=2,2,6,6-tetramethylpiperidide), a template base as its deprotonating action is dictated primarily by its 12 atom ring structure, is studied with the common N-heterocyclic carbene (NHC) IPr [1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene]. Remarkably, magnesiation of IPr occurs at the para-position of an aryl substituent, sodiation occurs at the abnormal C4 position, and a dative bond occurs between normal C2 and sodium, all within a 20 atom ring structure accommodating two IPr(2-). Studies with different K/Mg and Na/Mg bimetallic bases led to two other magnesiated NHC structures containing two or three IPr(-) monoanions bound to Mg through abnormal C4 sites. Synergistic in that magnesiation can only work through alkali-metal mediation, these reactions add magnesium to the small cartel of metals capable of directly metalating a NHC.

We disclose the synthesis and structural characterization of the first acid-free anionic oxoborane, [K(2.2.2-crypt)][(HCDippN) 2 BO] (1), which is isoelectronic with classical carbonyl compounds. 1 can readily be accessed from its borinic acid by a simple deprotonation/sequestration sequence. Crystallographic and DFT analyses support the presence of a polarized terminal B=O double bond. Subsequent π bond metathesis converts the B=O bond to a heavier B=S containing system, affording the first anionic thioxoborane [K(2.2.2-crypt)] [(HCDippN) 2 BS] (2), isoelectronic with thiocarbonyls. Facile B=O bond cleavage can also be achieved to access B−H and B−Cl bonds, and via a remarkable oxide (O 2− ) ion abstraction to generate a borenium cation [(HCDippN) 2 B(NC 5 H 5 )][OTf] (4). By extension, 1 can act as an oxide transfer agent to organic substrates, a synthetic role traditionally associated with transition metal compounds. Hence we show that B−O linkages, which are often considered to be thermodynamic sinks, can be activated under mild conditions towards bond cleavage and transfer, by exploiting the higher reactivity inherent in the B=O double bond.

By sequentially treating the unsaturated carbene IPr (IPr = 1,3-bis-(2,6-diisopropylphenyl)imidazol-2-ylidene) with heavier alkalimetal alkyls NaR or KR (R = CH2SiMe3) and GaR3, novel heteroleptic gallates 1 and 2 have been prepared. Incorporating anionic NHC ligands, these bimetallic complexes react selectively with electrophilles to afford neutral abnormal NHC Ga complexes under mild conditions.

Two-coordinate cations [(N-nacnac)E]+ (E = Si, Ge, Sn) react differently towards ammonia/amines: simple adduct formation (Ge,Sn) contrasts with N–H activation (Si).

An oxidation/substitution strategy for the synthesis of silicon analogues of classical organic carbonyl compounds is reported, by making use of a novel β‐diketiminate‐supported sila‐acyl chloride—the first example of such a compound isolated without the use of a stabilizing Lewis acid. Nucleophilic substitution at the SiIV center allows direct access to the corresponding sila‐aldehyde and sila‐ester. An alternative approach utilizing the reverse order of synthetic steps is thwarted by the facile rearrangement of the corresponding SiII systems featuring either H or OR substituents. As such, the isolation of (N‐nacnac)Si(O)Cl represents a key step forward in enabling the synthesis of sila‐carbonyl compounds by a synthetic approach ubiquitous in organic chemistry.