Lithium, Magnesium, and Zinc Iminophosphorano(8-quinolyl)methanide Complexes:  Syntheses, Characterization, and Activity in ε-Caprolactone Polymerization

Abstract

Lithiation of R2P(CH2C9H6N-8)NBut (R = Ph, 3; R = Pri, 4) with an equivalent of BunLi afforded lithium iminophosphorano(8-quinolyl)methanide [Li{CH(8-C9H6N)P(Ph2)NBut}(THF)] (5) and [Li{CH(8-C9H6N)P(Pri 2)NBut}]2 (6), respectively. Reaction of 4 with Et2Mg yielded magnesium iminophosphorano(8-quinolyl)methanide complex (7). Treatment of 6 with ZnCl2 gave [Zn(Cl){CH(8-C9H6N)P(Pri 2)NBut}] (8), which was transformed into alkylated zinc complexes [Zn(R1){CH(8-C9H6N)P(Pri 2)NBut}] (R1 = Ph, 9; R1 = Me, 10) by treating with R1Li or R1MgX. Ethylzinc complexes [Zn(Et){CH(8-C9H6N)P(R2)NBut}] (R = Ph, 11; R = Pri, 12) were obtained by reaction of 3 or 4 with an equivalent of Et2Zn. Compounds 2 and 4 − 12 were characterized by 1H, 13C{1H}, and 31P{1H} NMR spectroscopy and elemental analyses. Structures of complexes 6 − 8 and 10 were further characterized by single-crystal X-ray diffraction techniques. The catalytic behaviors of complexes 7 and 9 − 12 in the ring-opening polymerization of ε-caprolactone was studied. Complex 7 exhibited high catalytic activity in the presence or absence of benzyl alcohol. Complexes 9 − 12 catalyzed the ring-opening polymerization of ε-CL in the presence of benzyl alcohol and exhibited first-order dependence on monomer concentration.

Synthesis, structure and reactivity study of magnesium amidinato complexes derived from carbodiimides and N,N′-bis(2,6-diisopropylphenyl)-1,4-diaza-butadiene ligands

“…In addition, two doublets with coupling constants of 6.6 and 6.4 Hz at 1.15 and 1.00 ppm were obtained due to the resonance of methyl protons present in the ligand. The 13 C{ 1 H} 5 NMR spectra was also in the expected range and very similar to that of complex 4. The solid-state structure of complex 7 was established by single-crystal X-ray diffraction analysis.…”

“…It was observed that in each case, a magnesium-carbon bond was inserted into the carbon-nitrogen double bond of either carbodiimides or Dipp 2 DAD to result in a monoanionic amido-imino ligand. 15 In a further reaction between 1 and N-aryliminopyrrolyl ligand 2-(2,6-i Pr 2 C 6 H 3 N=CH)C 4 H 3 NH (ImpDipp-H) in 1:2 molar ratio, a new magnesium complex [Mg(ImpDipp) 2 {CyN=C(CH 2 Ph)NHCy}] (5), with one amidinato and two aryliminopyrrolyl ligands in the coordination sphere was obtained in good yield. In contrast, the homoleptic magnesium complex 4 reacted with one equivalent of Naryliminopyrrolyl ligand (ImpDipp-H) to produce another mixed ligated magnesium complex [Mg{DippN=C(CH 2 Ph)CH 2 NDipp}(ImpDipp)] (6), with a benzylated DAD ligand and aryliminopyrrolyl ligands in the coordination…”

Phosphorus‐Bearing Lithium Compounds in Modern Synthesis

“…Treatment of phosphazene 58 with n-BuLi afforded the lithiated bridged dimer 59, which was transformed into the zinc complex 60 by reaction with ZnCl 2 and subsequent addition of R 1 Li or R 1 MgX [24]. Complex 60 showed good activity as catalyst/initiator in the ring-opening polymerization of ϵ-caprolactone in the presence of benzyl alcohol.…”

Alkali/coinage metals—organolithium, organocuprate chemistry

“…175 The first aryland thiophene-containing Au(II) complex, formed by radical transfer and gold-gold bond formation, has been reported. In this context, meso-hexakis(pentafluorophenyl)-substituted [26]hexaphyrin(1.1.1.1.1.1) has proved an interesting and strongly aromatic (26p) target for study. Gold-carbon bond lengths were found to decrease in the order Au(I) 4 Au(III) 4 Au(II).…”

“…15 The reductive alkylation of terminal and 2,2-disubstituted epoxides by lithium 2,2,6,6-tetramethylpiperidide has been tested, with reagents exposed to a mixture of the amide and a second organolithium, and fully regio-and highly stereoselective alkene synthesis has resulted. 26 The synthesis and structural characterisation of N,N-diisopropylaminomethyllithium has been reported, along with the products of partial and full oxidation. 16 Work on the entrapment of hydride ions using alkali metal cages has proceeded.…”