Thiophosphinoyl-Tethered Ylide-Substituted Heavier Carbenes: Synthesis, Structures and Stabilities.

The synthesis and structure analysis of a series of mono and diylide-substituted tetrylenes of type YEX and Y E (E=Ge, Sn, Pb; X=Cl or Br) using a thiophosphinoyl-tethered metallated ylide (Y=Ph P(S)-C-P(pip)Ph with pip=piperidyl) is reported, amongst the first ylide-substituted plumbylenes. The tetrylenes feature distinct trends in the spectroscopic and structural properties of the ylide ligand with increasing atomic number of the tetrel element. For instance, an increasingly high-field shifted signal for the thiophosphinoyl group is observed in the P{ H} NMR spectrum as a consequence of the increasing polarity of the element-carbon bond, which likewise results in a shortening of the ylidic C-P bond in the solid-state structure.

Catalytic Activation of Imines by Chalcogen Bond Donors in a Povarov [4+2] Cycloaddition Reaction.

Recently, chalcogen bonding has been investigated in more detail in organocatalysis and the scope of activated functionalities continues to increase. Herein, the activation of imines in a Povarov [4+2] cycloaddition reaction with bidentate cationic chalcogen bond donors is presented. Tellurium-based Lewis acids show superior properties compared to selenium-based catalysts and inactive sulfur-based analogues.

Ylide-Substituted Phosphines with a Cyclic Ylide-Backbone: Angle Dependence of the Donor Strength.

Ylide-substituted phosphines (YPhos) have been shown to be highly electron-rich and efficient ligands in a variety of palladium catalyzed transformations. Here, the synthesis and characterization of novel YPhos ligands containing a cyclic backbone architecture are reported. The ligands are easily synthesized from a cyclic phosphonium salt and the chlorophosphines CyPCl () and Cy(Flu)PCl (, with Flu = 9-methylfluorenyl) and were characterized in both solution and solid states.

Expected and Unexpected Reactivities of Homoleptic LiNacNac and Heteroleptic NacNacMg(TMP) β-Diketiminates toward Various Small Unsaturated Organic Molecules.

Homoleptic LiNacNac forms simple donor-acceptor complexes with ,'-dicyclohexylcarbodiimide (CyN═C═NCy), triphenylphosphine oxide (PhP═O), and benzophenone (PhCO). These crystallographically characterized compounds could be regarded as model intermediates en route to reducing the N═C, P═O, and C═O bonds of unsaturated substrates. Heteroleptic NacNacMg(TMP) intriguingly functions as a TMP nucleophile both with -BuNCO and -BuNCS, producing a urea or thiourea derivative respectively attached to Mg, though the NacNac ligand in the former reaction also engages noninnocently with a second -BuNCO molecule via insertion at the reactive NacNac backbone γ-carbon site.

Backbone Reactivity of Lithium β-Diketiminate (NacNac) Complexes with CO , tBuNCO and iPrNCO.

Though alkali metal NacNac (β-diketiminate) complexes have been utilised in synthesis as NacNac-transfer agents, studies of them in their own right with small molecules are exceptionally rare. Here, the lithium compound of the common 2,6-diisopropylphenyl-β-methyldiketiminate [NacNac(Dipp, Me)] ligand is investigated with carbon dioxide and isocyanates. In all four cases reaction occurs at the backbone γ-C atom of the NacNac ligand, which redistributes electronically into a diimine.