Synthesis and structures of isopropyl-β-diketiminato copper(I) complexes

Abstract

The reaction of N,N'-diisopropyl-2-amino-4-iminopent-2-ene (nacnac i-Pr H, 1) either with CuOt-Bu or with a mixture of mesityl copper and 10% CuOt-Bu afforded, in the presence of PPh 3 , CN(C 6 Me 2 H 3 ), or MeCN, the Lewis base coordinated complexes nacnac i-Pr CuPPh3Á0.5 C6H14 (2), nacnac i-Pr CuCN(C6Me2H3) (3), and nacnac i-Pr Cu(NCMe) (4). Compounds 2, 3, and 4 were characterized by single-crystal X-ray diffraction studies. Compound 4 afforded two species in deuterated benzene in a 2:1 ratio, which were assigned to {nacnac i-Pr Cu}2(m-NCMe) and nacnac i-Pr CuNCMe (4). Upon addition of 5 equiv. of MeCN, the two sets collapsed into that of 4. No copper complexes were formed in the presence of styrene, stilbene, or diphenylacetylene.

Copper‐Catalyzed Amination of Arylboronates with N,N‐Dialkylhydroxylamines

“…Subsequent transmetalation with the neopentylglycol boronate 1 furnishes the monoarylcopper 7. [18] Additionally notable is that under the current system the monoarylcopper species does not couple with the hydroxylamine 2, whereas [(phen)CuC 6 F 5 ] does couple very smoothly even without any additives in our previous work. [17] The aniline product 3 would the result from the reaction of 8 with the hydroxylamine 2, and the monoarylcopper 7 is regenerated to complete the catalytic cycle.…”

Improved Synthesis of Unsymmetrical N‐Aryl‐N′‐alkylpyridyl ß‐Diketimines Using Molecular Sieves and their Lithium Complexes

“…β‐diketimines are usually prepared by the condensation of acetylacetone with two equivalents of a primary amine in the presence of acid . It is worthwhile mentioning that most β‐diketimines have symmetrical N, N′ ‐aryl or N, N′ ‐alkyl substituents,, , but only a few unsymmetrical N ‐aryl‐ N′ ‐alkyl β‐diketimines (UNAAD) have been reported due to their tedious synthetic procedures . Symmetric β‐diketimines can be synthesized under several conditions with or without the azeotropic removal of water or with stoichiometric or catalytic amounts of acid , , .…”

Intramolecular π-stacking in copper(i) diketiminate phenanthroline complexes

“…On the other hand, complexes 4b and 5b with very strong or no possible p-stacking interactions, respectively, show only minor changes in their absorption maxima between toluene and diethyl ether solution. In comparison to 5b, 13 C NMR spectra of 1b-4b in benzene-d 6 show a high-field shift of C10A/C10B (C30 and C31 in the crystal structure of 4b, Fig. 3), which qualitatively correlates with the observed p-stacking and might be attributed to the ring current effect of the p-stacked benzyl substituent.…”

“…Substitution of the 2,9-positions of the phenanthroline ligand, avoiding coordinating solvents and excited state equilibration with organic auxiliaries have been used as strategies to avoid excited state quenching. We have previously reported the syntheses of copper(I) complexes with N-alkyl substituted diketiminate ligands (nacnac R ), [11][12][13] in particular nacnac Bn , 12 in which p-stacking interactions are present in most of its complexes. We envisaged that this ligand would allow a "sandwiched" p-stacking arrangement of the phenanthroline ligand between the N-benzyl substituents, thus minimising excited state distortion (Chart 1).…”