Functionally substituted arylcopper compounds: synthesis, structure, and reactivity of [2-(2-oxazolinyl)aryl]copper(I) species

Abstract

Arylcopper(1) compounds containing an oxazoline substituent in the position ortho to the Cu-C bond have been synthesized from the corresponding aryllithium compounds and CuBr. Depending on the order of addition this reaction afforded either a pure arylcopper(1) compound (slow addition of CuBr to the aryllithium reagent) or a mixture of arylcopper (1) four-electron bridging bromine atoms (Cu-Br = 2.524 (3) 8, (mean); Cu-Cu = 3.023 (4) 8, (mean)). The oxazoline substituent is coordinated via the nitrogen atom (Cu-N = 1.968 (4) 8, (mean)). Ullmann biaryl coupling reactions of the new organocopper(1) compounds with 2-iodopiperonal imine were little influenced by a hetero substituent in either the arylcopper(1) compound or the aryl iodide anchoring group. Moreover, since the addition of P(OMeI3 did not influence the coupling reaction, it can be concluded that "external" ligands do not have a critical role in these reactions. The results of this study show clearly the important influence that an ortho-chelating substituent (i.e. the 2-oxazolinyl group in the present compounds) can have on both the structural features and the reactivity of the arylcopper compounds.

Novel Copper(I) Clusters with 2‐(Diphenylphosphanyl)anilide Ligands. Synthesis and Crystal Structures of [Cu6X2(NHR)4] (X = Cl, Br, I; R = C6H4‐2‐PPh2)

“…However, like in the case of compound 1 the mutual arrangement of the HL – ligands leads to roughly D 2 symmetric molecules (pseudo C 2 axes passing through Cu2 and Cu2 i and the midpoints of the octahedron edges Cu1–Cu3 and Cu1 i –Cu3 i ). It is worth mentioning that a similar cluster pattern has been observed for the copper(I) aryl species [Cu 6 (C 6 H 4 ‐2‐NMe 2 ) 4 Br 2 ] and [Cu 6 Br 2 (MeOxl) 4 ] [MeOxl = 2‐(4,4‐dimethyl‐2‐oxazolyl)‐5‐methylphenyl] …”

“…The corresponding values for Cu–Br complexes are: 233.8–305.8 pm, median 255.1 pm (963 entries) and for Cu–I complexes: 244.5–311.0 pm, median 268.9 pm (3207 entries) . In the case of the above mentioned hexanuclear Cu I aryl complex [Cu 6 Br 2 (MeOxl) 4 ], the Cu–Br distances are 247.0–257.0 pm . A comparison of the Cu– X –Cu angles at the halogen atoms reveals a decrease with increasing Cu– X distances [ X = Cl: 70.2(1)–71.0(1)°, Br: 66.1(1)–67.3(1)°, I: 61.0(1)–62.3(1)°].…”

Structures and Reactivities of Organocopper Compounds

“…Although both ligand systems contain a potentially coordinating nitrogen atom in the g-position (with respect to the copper atom), [Cu 4 (C 6 H 4 CH 2 NMe 2 -2) 4 ] is a tetramer while the latter compound (see Fig. 1.12, left) is a dimer [70].…”

PLATONSQUEEZE: a tool for the calculation of the disordered solvent contribution to the calculated structure factors

“…Close inspection of contoured difference electrondensity maps showed this to be due to unaccounted-for continuous density in infinite channels filled with unknown solvent. This prompted us 25 years ago to investigate the back-Fourier transform approach, based on an idea gleaned from a footnote in a paper by Wehman et al (1988). A prototype proof-of-principle implementation for this, including a number of ad hoc programs, was developed and published as the BYPASS procedure (van der Sluis & Spek, 1990b), based around the SHELX76 (Sheldrick, 2008) least-squares refinement program available to us at that time.…”