The Syntheses and Electrochemical Studies of a Ferrocene Substituted Diiminopyridine Ligand and Its P, S, Se, and Te Complexes

Ligand-enforced geometric constraints and associated reactivity in p-block compounds

The geometry at an element centre can generally be predicted based on the number of electron pairs around it using valence shell electron pair repulsion (VSEPR) theory. Strategies to distort p-block compounds away from these predicted geometries have gained considerable interest due to the unique structural outcomes, spectroscopic properties or reactivity patterns engendered by such distortion. This review presents an up-to-date group-wise summary of this exciting and rapidly growing field with a focus on understanding how the ligand employed unlocks structural features, which in turn influences the associated reactivity. Relevant geometrically constrained compounds from groups 13-16 are discussed, along with selected stoichiometric and catalytic reactions. Several areas for advancement in this field are also discussed. Collectively, this review advances the notion of geometric tuning as an important lever, alongside electronic and steric tuning, in controlling bonding and reactivity at p-block centres.

Geometrically Deformed and Conformationally Rigid Phosphorus Trisamides Featuring an Unsymmetrical Backbone

Nonclassical P(III) centers have attracted much attention in recent years. Incorporating a P(III) center in a rigid bicyclic platform offers a particularly attractive way to invoke significant geometric distortion of the phosphorus atom that may in turn induce unusual reactivity. Although still relatively scarcely explored, phosphorus centers enforced in a non-C3 symmetry have gained significant traction lately. However, the current scaffolds are based on a relatively limited set of design principles and ligand platforms associated therewith. This work is focussed on the synthesis as well as versatile oxidation, addition and coordination chemistry of a geometrically distorted P(III) species featuring a synthetically modular, nonsymmetric trisamine platform derived from 2-(methylamino)-N-(2-(methylamino)phenyl)benzenesulfonamide.

Antimony diiminopyridine complexes

The stoichiometric reactions of antimony trichloride, trimethylsilyl trifluoromethanesulfonate, and diiminopyridine ligands lead to the formation of N,N',N''-chelated SbCl₂ cationic complexes. Methyl and phenyl substituents on the imine carbons of the ligand yielded structures with a lone pair on antimony and the hydrogen substituted variant was notably different as it forms a Menshutkin complex with meta-xylene in the solid-state.

Unique molecular geometries of reduced 4- and 5-coordinate zinc complexes stabilised by diiminopyridine ligand

Stepwise reduction of the diiminopyridine complex dimpyrZnCl₂ by KC₈ leads to compounds dimpyrZnCl (2), dimpyrZnCl(DMAP) (3) and dimpyrZn(DMAP)₂ (4) having unusual square-planar and see-saw geometries.

Antimony(III) and bismuth(III) amides containing pendant N-donor groups--a combined experimental and theoretical study

N,N- and N,N,N-chelated antimony(III) and bismuth(III) chlorides L(1-3)MCl2 1-4 [for L(1): M = Sb (1), for L(2): M = Sb (2) and for L(3): M = Sb (3) and Bi (4)], containing ligands L(1-3) derived from the pyrrole ring (where L(1) = C4H3N-2-(CH[double bond, length as m-dash]N-2',6'-iPr2C6H3), L(2) = C4H2N-2,5-(CH2NMe2)2, L(3) = C4H2N-2,5-(CH2NC4H8)2), were prepared by the treatment of lithium precursors with SbCl3 or BiCl3. Molecular structures 1-4 of were described both in solution (NMR spectroscopy) and in the solid state (single-crystal X-ray diffraction analysis). Structures of 1-4 were also subjected to a density functional theory study.

A coordination compound of Ge(0) stabilized by a diiminopyridine ligand

Reduction of the cationic Ge(II) complex [dimpyrGeCl][GeCl3] (dimpyr=2,6-(ArN=CMe)2NC5H3, Ar=2,6-iPr2C6H3) with potassium graphite in benzene affords an air sensitive, dark green compound of Ge(0), [dimpyrGe], which is stabilized by a bis(imino)pyridine platform. This compound is the first example of a complex of a zero-valent Group 14 element that does not contain a carbene or carbenoid ligand. This species has a singlet ground state. DFT studies revealed partial delocalization of one of the Ge lone pairs over the π*(C=N) orbitals of the imines. This delocalization results in a partial multiple-bond character between the Ge atom and imine nitrogen atoms, a fact supported by the X-ray crystallography and IR spectroscopy data.

The tipping point of the inert pair effect: experimental and computational comparison of In(I) and Sn(II) bis(imino)pyridine complexes

The autoionization reaction of neutral bis(imino)pyridine and SnX2 led to three compounds [{ArN[double bond, length as m-dash]CPh}2(NC5H3)]SnX(+)SnX3(-) (Ar = 2,6-(2,5-(t)Bu2C6H3), X = Cl, Br; Ar = 2,6-(2,6-Me2C6H3), X = Cl) which display, within the same species, cations and anions possessing Sn(ii) centers. Computational analysis compared the ligated Sn(ii) cations with bis(imino)pyridine In(i) complexes that showed unprecedented weak metal-ligand covalent interactions, consistent with the In(i) 5s(2) electrons remaining as an inert nonbonding pair. Analysis of the metal-ligand bonding indicates that the chloride ligand of the Sn(ii) complex induces promotion of the metal 5s(2) electron pair to a stereochemically active hybridized orbital, which, in turn, allows strong coordination of the bis(imino)pyridine to Sn.