Soluble Monometallic Salen Complexes Derived from O‐functionalized Salicylaldehydes as Metalloligands for the Synthesis of Heterobimetallic Complexes

Abstract

The reaction of 2,3-diamino-2,3-dimethylbutane (tmen) with 3-hydroxysalicylaldehyde (3hsal), 4-hydroxysalicylaldehyde (4hsal), and 5-hydroxysalicylaldehyde (5hsal) or 3-carboxysalicylaldehyde (3csal) gave the hydroxy-functionalized salen ligands H 4 3hsaltmen, H 4 4hsaltmen and H 4 5hsaltmen, or the 3-carboxyfunctionalized ligand H 4 3csaltmen, which were characterized by 1 H, 13 C{ 1 H} NMR and IR spectroscopy. The nickel(II) and copper(II) complexes [Ni(H 2 3hsaltmen)], [Ni(H 2 4hsaltmen)], [Ni(H 2 5hsaltmen)], [Cu(H 2 3hsaltmen)] and [Cu(H 2 4hsaltmen)] were synthesized in high yield (78Ϫ99 %) starting from H 4 3hsaltmen, H 4 4hsaltmen and H 4 5hsaltmen and the corresponding metal(II) acetates. The complexes are soluble in acetone, ethanol, methanol, thf and dmso. The reaction of H 4 3csaltmen and nickel(II) acetate gave [Ni(H 2 3csaltmen)] in 40 % yield. The disodium salt of the corresponding copper(II) complex [Cu(Na 2 3csaltmen)] was obtained in 66 % yield in a template reaction from 3-carboxysalicylaldehyde, tmen, copper(II) acetate and sodium hydroxide, and was characterized by EPR spectroscopy and mass spectrometry. All complexes were identified by IR spectros-Scheme 1 Synthesis of hydroxy-functionalized salen ligands and nickel(II) and copper(II) complexes thereof. plexes in epoxidation reactions will be reported in a forthcoming paper [11]. Results and Discussion Synthesis of hydroxy-functionalized salen ligands and complexes thereofNickel(II) and copper(II) complexes of hydroxy-functionalized salen ligands, prepared from 4-hydroxysalicylaldehyde and ethylenediamine [12], are readily soluble only in dmso; moderately soluble in acetone, 1,4-dioxane and thf; and slightly soluble in acetonitrile, chloroform, diethyl ether, ethanol, ethyl acetate and toluene.To increase the solubility of the hydroxy-functionalized salen complexes, the alkyl-substituted ethylenediamine derivative 2,3-diamino-2,3-dimethylbutane [12] (tmen) was employed, and the reaction with commercially available 3hydroxysalicylaldehyde (3hsal), 4-hydroxysalicylaldehyde (4hsal) and 5-hydroxysalicylaldehyde (5hsal) gave the hydroxy-functionalized salen ligands H 4 3hsaltmen, H 4 4hsaltmen and H 4 5hsaltmen in 68-76 % yield (Scheme

Soluble monometallic salen complexes derived from O-functionalised diamines as metalloligands for the synthesis of heterobimetallic complexes

“…In accordance with our previous work 9 we investigated the electrochemical properties of the mono-and heterobimetallic salen complexes. Besides many cyclovoltammetric measurements of This journal is © The Royal Society of Chemistry 2010 heterobimetallic complexes, 35 wherein the two metals are bridged by donor atoms, there exist only a few examples of cyclovoltammetric investigations of heterobimetallic complexes which contain two transition metals located at least two bonds apart.…”

“…6 This is in contrast to the large number of existing studies on alkoxy-substituted salen complexes and early/late heterobimetallic compounds thereof, 7 with special focus on their magnetic behaviour. 8 We recently reported the synthesis of soluble monometallic salen complexes derived from O-functionalised salicylaldehydes 9 and hydroxy-functionalised diamines 10 as metalloligands for the synthesis of heterobimetallic complexes and immobilisation of some of these complexes on organo-modified mesoporous silica gel as well as their catalytic activity in the epoxidation of olefins. 11 Now we report the synthesis and characterisation of two new salen ligands derived from carboxy-functionalised diamines, Na(H 2 bsalcen) and H 3 bsal4cpn, 12 and their mono-and heterobimetallic complexes.…”

4‐Thiolatobenzoato‐Bridged Rhodium/Zirconium Complexes: 32‐Membered Metallamacrocycles and Their Linear Dinuclear Counterparts

“…To stabilise the monomeric form, an excess of triethylphosphane must be used. (8), O2-C25 126.9(7), Rh1-S1 241.4(2), Rh1-P1 230.5(2), Rh1-P2 224.7(2), Rh1-P3 232.7(2); O1-Zr1-O2 56.6(2), O1-Zr1-C46 73.8(3), O1-C25-O2 117.9(6), S1-Rh1-P1 82.93(6), S1-Rh1-P2 166.98(7), S1-Rh1-P3 83.94(6), P1-Rh1-P2 96.76(6), P2-Rh1-P3 101.05(6), P1-Rh1-P3 153.70(7), Rh1-S1-C19 104.8(2). Selected bond lengths [pm] and bond angles [°] for 4: Zr1-O1 229.5(5), Zr1-O2 228.6(5), Zr1-O3 207.8(6), O1-C25 128(1), O2-C25 124.8(9), Rh1-S1 241.4(2), Rh1-P1 231.0(2), Rh1-P2 225.0(3), Rh1-P3 232.6(3); O1-Zr1-O2 56.4(2), O1-Zr1-O3 76.8(2), O1-C25-O2 117.6(8), S1-Rh1-P1 83.06(9), S1-Rh1-P2 167.39(9), S1-Rh1-P3 84.25(9), P1-Rh1-P2 96.39(9), P2-Rh1-P3 100.64(9), P3-Rh1-P1 154.79(9), Rh1-S1-C19 106.2(3).…”

“…(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) centre to one coordination site of a di-or multifunctional, potentially bridging ligand, different concepts are known from the literature, for example exploitation of the chelate effect [8] or the use of donor atoms with different coordination behaviour [9] according to the hard and soft acids and bases concept of Pearson. [10] We have previously employed S,O ligands, such as mercaptocarboxylic acids, which show high bonding selectivity in the synthesis of heterometallic complexes [11] if they cannot bind in a chelating fashion.…”

Synthesis, crystal structure, magnetic properties and second harmonic generation of a new noncentrosymmetric coordination compound: Triaqua(4-amino-6-methoxypyrimidine) cuprate(II)sulfate

“…They can break the DNA chains in the presence of H 2 O 2 and reducing agents, and are used broadly as foot printing agents for proteins and DNAs [10], probes of the dimensions of the minor groove of duplex structures [11], and identifiers of transcription starting sites [12]. Copper(II) complexes have been probed electrochemically [13,14] magnetically [15][16][17][18][19] and by EPR [20][21] for their electronic situation. The Cu(II) complexes have different molecular geometries, such as tetrahedral, square planar, square pyramidal and octahedral [22].…”