Richard A. Kemp

Catenation is common for the light main‐group elements whereas it is rare for the heavy elements. Herein, we report the first example of a neutral molecule containing a Bi₄ chain. It is prepared in a one‐step reaction between bismuth trichloride and bis(diisopropylphosphino)amine in methanol suspension. The same reaction carried out in dichloromethane gives quite different products. All products have been characterized spectroscopically and using single‐crystal X‐ray analysis.

[Tl₂(salo-Bu^t)] (1, shown) and [Tl₂(saloPh-Bu^t)] (2) were synthesized and characterized for use as monitors for deep subterranean fluid flows.

A family of magnesium and calcium salen-derivatives was synthesized and characterized for use as subterranean fluid flow monitors. For the Mg complexes, di-n-butyl magnesium ([Mg(Buⁿ)₂]) was reacted with N,N′-ethylene bis(salicylideneimine) (H₂-salen), N,N′-bis(salicylidene)-1,2-phenylenediamine (H₂-saloPh), N,N′-bis(3,5-di-t-butylsalicylidene)-ethylenediamine (H₂-salo-Bu^t), or N,N′-bis(3,5-di-t-butylsalicylidene)-1,2-phenylenediamine (H₂-saloPh-Bu^t), and the products were identified by single-crystal X-ray diffraction as [(κ³-(O,N,N′),μ-(O′)saloPh)(μ-(O),(κ²-(N,N′),μ-(O′)saloPh)₂(μ-(O),κ³-(N,N′,O′)saloPh′)Mg₄]·2tol (1·2tol; saloPh′ = an alkyl-modified saloPh derivative generated in situ), [(κ⁴-(O,N,N′,O′)saloPh)Mg(py)₂]·py (2·py), [(κ⁴-(O,N,N′,O′)salo-Bu^t)Mg(py)₂] (3), [(κ⁴-(O,N,N′,O′)saloPh-Bu^t)Mg(py)₂]·tol (4·tol), and [(κ³-(O,N,N′),μ-(O′)saloPh-Bu^t)Mg]₂ (5), where tol = toluene; py = pyridine. For the Ca species, a calcium amide was independently reacted with H₂-salo-Bu^t and H₂-saloPh-Bu^t to generate the crystallographcially characterized compounds: [(κ⁴-(O,N,N′,O′)salo-Bu^t)Ca(py)₃] (6), [(κ⁴-(O,N,N′,O′)saloPh-Bu^t)Ca(py)₃]·py (7·py). The bulk powders of these compounds were further characterized by a number of analytical tools, where 2–7 were found to be distinguishable by Fourier transform infrared and resonance Raman spectroscopies. Structural properties obtained from quantum calculations of gas-phase analogues are in good agreement with the single-crystal results. The potential utility of these compounds as taggants for monitoring subterranean fluid flows was demonstrated through a series of experiments to evaluate their stability to high temperature and pressure, interaction with mineral surfaces, and elution behavior from a loaded proppant pack.

Five different coordination motifs were observed upon reaction of the simple group 13 Lewis acids MCl₃ (M = In, Ga, Al, B) or BF₃·Et₂O with the ambidentate bis(diisopropylphosphino)amine ligand HN[P(i-Pr)₂]₂. In a 1:1 reaction mixture, the softer Lewis acids InCl₃, GaCl₃ and BCl₃ coordinate to one of the two P atoms of the ligand. In contrast, AlCl₃ and BF₃ prefer coordination to the harder N atom. In all cases, the acidic N–H proton is shifted to P upon complexation with a metal. By altering the reaction stoichiometry, 2:1 metal–ligand complexes could be isolated for three of the combinations. BCl₃ gives a bis-adduct via the two P atoms. GaCl₃ produces a salt consisting of a [GaCl₄]⁻ anion and a P,P-chelated [LGaCl₂]⁺ cation. Most unexpectedly, the reaction with InCl₃ in methanol resulted in solvent deprotonation by the ligand to give two symmetric [(i-Pr₂PH)₂N]⁺ cations in which all the basic P sites are coordinated to H rather than the group 13 Lewis acid. These cations are balanced by the unique complex dianion [(MeO)₆In₄Cl₈·2MeOH]^2–. All complexes were characterized with a combination of multinuclear NMR spectroscopy and single-crystal X-ray diffraction.

The structure of the title compound, {(NH₄)₂[Cu(C₂O₄)₂]}_n, at 100 K has monoclinic (P2₁/c) symmetry with the Cu^IIatom on an inversion center. The compound has a polymeric structure due to long Cu...O interactions which create [Cu(C₂O₄)₂] chains along theaaxis. The structure also displays intermolecular N—H...O hydrogen bonding, which links these chains into a three-dimensional network.

Correction for ‘Facilitated carbon dioxide reduction using a Zn(II) complex’ by Elizabeth S. Donovan et al., Chem. Commun., 2016, DOI: 10.1039/c5cc07318a.