Synthesis, Structures and Characterization of the Calcium Pyrrolates [Ca{(2‐(dimethylaminomethyl)pyrrolyl}₂ donor_n] (donor = THF and pyridine, n = 2; DME and TMEDA, n = 1) as Potential Precursors for Solid‐State Applications

Abstract

The synthesis and characterization of novel alkaline earth metal pyrrolyl derivatives is described. The target molecules were synthesized using transamination and metallation protocols, involving either the treatment of calcium bis[bis(trimethylsilyl)]amide with two equivalents of 2‐(dimethylaminomethyl)pyrrole (2‐DMAMP) or the reaction of elemental calcium with two equivalents of 2‐DMAMP. Different donors, namely THF, pyridine (py), DME (dimethoxyethane), and TMEDA (N,N,N′,N′‐tetramethylethylenediamine) were utilized to study their influence on the structural chemistry of the target compounds. In order to compare the influence of the metal coordination on the pyrrole ligand, we included the crystal structure of the free 2‐DMAMP ligand. All new compounds were characterized using 1H, 13C NMR and IR spectroscopy in addition to X‐ray crystallography. Crystal data with Mo‐Kα radiation (λ = 0.71073 Å) are as follows: 1: [Ca(2‐DMAMP)2(THF)2], a = 15.440(2) Å, b = 14.992(2) Å, c = 10.175(1) Å, β = 94.9(3)°,V= 2346.6(6) Å3, Z = 4, monoclinic, space group P21/c, R1(all data) = 0.0981; 2: [Ca(2‐DMAMP)2(py)2], a = 9.168(6) Å, b = 10.418(7) Å, c = 13.329(8) Å, α = 85.9(1)°, β = 72.9(1)°, γ = 86.2(1)°, V = 1212.2(1) Å3, Z = 2, triclinic, space group P$\bar 1$ , R1 (all data) = 0.0711; 3: [Ca(2‐DMAMP)2(DME)], a = 10.814(1) Å, b = 12.907(1) Å, c = 15.170(1) Å, V = 2117.3(3) Å3, Z = 4, orthorhombic, space group P212121, R1 (all data) = 0.0729; 4: [Ca(2‐DMAMP)2(TMEDA)], a = 9.403(6) Å, b = 15.810(1) Å, c = 15.417(1) Å, V = 2292.0(3) Å3, Z = 4, orthorhombic, space group Pbcn, R1 (all data) = 0.0997; 5: 2‐DMAMP, a = 10.8820(7) Å, b = 15.2186(10) Å, c = 9.7578(6) Å, β = 109.736(2)°,V = 1521.05(17) Å3, Z = 2, monoclinic, space group Cc, R1 (all data) = 0.0382. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Advances in alkaline earth-nitrogen chemistry

“…The most prominent pyrrole derivatives are based either on substituted pyrrolato complexes of the form [M(pyr*) 2 (thf)] (where M = Ca, Sr, and pyr* = 2,5-di-tert-butylpyrrolate) or [159,160]. The calcium complexes of 2-DMAMP exhibit 6-coordinate metal centers, with the THF and pyridine adducts displaying trans-oriented ligands and donors and the DME and TMEDA adducts displaying cis-oriented ligands (Fig.…”

Synthesis and Structures of Monomeric Magnesium, Calcium, Strontium, and Barium Amides Involving the N,N-(2,4,6-Trimethylphenyl)(trimethylsilyl)amido Ligand

“…Because these impurities are detrimental for the use of the materials in electronics applications, alternative source materials are needed. However, the preparation of nonsilylated heavy alkaline earth metal amides has proven to be very difficult, and oxygen-free examples are limited to pyrazolates 6d, and intramolecular coordinating pyrrolates …”

Group 2 Mediated Dehydrocoupling

“…Indeed, the activity of Group 2 amides and alkyls with alcohols, pyrroles, terminal alkynes, phosphines and C-H acidic heterocycles has been shown to yield alkoxide, [61][62][63] pyrrolide, 64 acetylide, [65][66][67][68] phosphide [69][70][71][72] and carbanion 73 fragments bound to a Group 2 centre alongside the respective protonated fragment; in the case of metal hexamethyldisilazides (IIa-d) this is an amine, as summarised in Scheme 1.3. …”