Synthesis and Spectroscopic and Structural Characterization of Oxamidato-Bridged Rhenium(I) Supramolecular Rectangles with Ester Functionalization

Abstract

Oxamidato-bridged Re(I)-based supramolecular rectangles with an ester functionality have been synthesized via an orthogonal bonding approach under solvothermal conditions. Self-assembly of Re2(CO)10 and oxamide ligands (H2L1 = N,N′-dibutyloxamide, H2L2 = N,N′-dioctyloxamide, H2L3 = N,N′-didodecyloxamide, and H2L4 = N,N′-dibenzyloxamide) with the pyridyl ligand phenyl-1,4-bis(isonicotinate) (pbin) has resulted in the formation of metallarectangles of general formula [{(CO)3Re(μ-η4-L)Re(CO)3}2(μ-pbin)2] (1–4), wherein L = N,N′-dibutyloxamidato (1), N,N′-dioctyloxamidato (2), N,N′-didodecyloxamidato (3), N,N′-dibenzyloxamidato (4) and pbin = phenyl-1,4-bis(isonicotinate). The metallarectangles have been characterized using spectroscopic techniques, and single-crystal X-ray structures have been obtained for 1 and 4. The guest binding ability of 2 has been investigated with a few aromatic amines and an amino ketone using electronic absorption and fluorescence emission spectroscopy, and the results revealed a strong binding interaction between host–guest species. The luminescence properties of 2 and 3 have been tuned using organic–aqueous solvent mixtures.

Self‐Assembly of Oxamidato‐Chelated ReI‐ and MnI‐Based Flexible Dinuclear Horse‐Stirrup‐Like Metallacycles

“…[45,46] The M···M nonbonding distances of the butyloxamidato-bridged dinuclear metallacycles are slightly longer than those of their benzyloxamidato-bridged analogues. The average Mn-CO bond lengths of 2 and 3 are 1.801 and 1.800 Å, whereas the Re-CO bond lengths of 5 and 6 are 1.909 and 1.901 Å, respectively.…”

“…In 1-6, two diastereotopic methylene protons adjacent to the nitrogen atom of the oxamidato bridge appeared as two doublets in the region δ = 5.33-3.13 ppm. [45,46] The aliphatic protons of bpe and bpp appeared as multiplets in the range δ = 3.47-2.27 ppm. The H 2 -H 4 protons of the butyloxamidato group appeared at δ = 1.80-0.97 ppm.…”

One-step synthesis of oxamidato bridged fac-Ru(CO)3 core based dinuclear compounds: Spectroscopic and structural characterisation

“…1 H NMR spectrum of compound 1 displayed two multiplets at d 3.99 and 3.16 ppm that were assigned to two diastereotopic H 1 and H 1 0 protons [59]. …”

Metal compounds with rigid polyaromatic ligands. Catalytic consequences

“…68 Some authors have suggested that the contribution of the π-back donation present in the NHC-metal bonding has not been seen as significant with respect to σ-bonding. 69,70 However, some experimental and theoretical approaches [71][72][73][74][75][76] have demonstrated that the NHC can act as π-acceptor via back donation from the M(d π ) orbitals, especially in those complexes that contains electron-rich metals. 77,78 Several methods have been developed to quantify and compare the electronic properties of NHC ligands.…”

“…The second approach involves the preparation of carbenephenylphosphinidene adducts. 71 The 31 P NMR chemical shift of these adducts allows the determination of the π-acceptor properties of the NHC ligands, which in combination with the TEP value, allows the estimation of the σ-donor character of the NHC ligand.…”