Triaryl- and trialkylantimony(V) Bis(catecholates) based on 1,1′-spirobis[3,3-dimethylindanequinone-5,6]: Spectroscopic and electrochemical studies

Abstract

Scientific interest in coordination and organome tallic antimony(V) derivatives is continuously increas ing in the recent two decades [1][2][3][4], which is due to the possibility of using these compounds in diverse areas of fundamental and applied science. These com plexes demonstrate structural variety from monomeric compounds to associated structures and supramolecu lar ensembles [5][6][7][8][9][10]. The antimony compounds are used as components of catalytic systems and reagents in fine organic and organometallic synthesis [11][12][13][14]. In addition, many organoantimony compounds dem onstrate antimicrobial properties and possess antitu mor activity [15][16][17].The chemistry of coordination compounds of o quinone and related ligands is widely developed to the present time [18][19][20] because of the use of their com plexes as model objects in magnetochemical studies, for the construction of molecular switchers, and as catalytic systems. Sterically hindered di o quinones are presently studied to a less extent, although they represent a promising type of ligands for the design of spatially ordered structures [21][22][23][24][25]. The introduction of various binding units (bridging groups) into the di o quinone structure makes it possible to change con siderably the character of mutual effects of the o quinone moieties in the di o quinone molecule and to vary the exchange magnetic interactions between the radical anion semiquinone derivatives from antiferro magnetic to ferromagnetic [22,24].In addition, the most part of studies of the o quinone complexes was carried out with the transi tion metal compounds, whereas the coordination chemistry of nontransition metals with redox active ligands is poorly studied [26]. This is also valid for the antimony o quinone complexes. Among the binuclear antimony complexes (bis(catecholate) derivatives), the derivatives of 4,4' di [(3 methyl 6 tert butyl o benzoquinone) and di o quinones based on 3,6 di tert butyl o benzoquinone containing the ethylene or piperazine bridging groups were described [27][28][29][30].The purpose of the present work is to synthesize antimony(V) bis(catecholate) complexes based on nonsymmetric 1,1' spirobis[3,3 dimethylindane quinone 5,6] (Q Spiro Q) and to study them by IR and NMR spectroscopy and cyclic voltammetry (CV). EXPERIMENTALThe synthesis and study of the properties of the complexes were carried out in evacuated ampules in the absence of oxygen. In all cases, the yields of the target products were higher than 90%. The solvents Triaryl and Trialkylantimony(V) Bis(catecholates) Based on 1,1' Spirobis[3,3 Dimethylindanequinone 5,6]: Abstract-A series of new binuclear bis(catecholate) antimony(V) complexes based on 1,1' spirobis[3,3 dimethylindanequinone 5,6] with various substituents at the central antimony atoms, R 3 Sb(Cat Spiro Cat)SbR 3 (I-IV) and R 3 Sb(Cat Br Spiro Br Cat)SbR 3 (V-VIII) (R = p fluorophenyl, phenyl, p tolyl, and ethyl), were synthesized. Spirobis(catecholates) I-III exhibit two one electron oxidation waves on the cycli...

Triaryl/trialkylantimony(V) catecholates with electron-acceptor groups

“…It was early shown that the redox properties of triarylantimony(V) 3,6-di-tert-butylcateholates [16] and spiro-bis-catecholates [17] depend on the electron donor/acceptor properties of aryl groups.…”

“…It was shown that the nature and donating properties of substituents in redox-active ligand has a significant effect on the redox properties of these complexes, and wherein triphenylantimony(V) derivatives of catecholates with electron-withdrawing groups are inert in the reaction with molecular oxygen, while electron donating substituents enhance activity of triphenylantimony(V) catecholates towards molecular oxygen and increase the yield of the corresponding spiroendoperoxides -products of molecular oxygen binding to antimony complexes [12e15]. The substituents at the central antimony atom were shown to influence the oxidation potential of the corresponding antimony(V) catecholate in a less degree than the substituents in redox-active ligand [16,17]. In the present paper we continue our study of this class of compounds, and describe new triethyl-and triarylantimony(V) catecholato complexes where aryl ¼ o-tolyl, p-fluorophenyl, p-chlorophenyl, with acceptor substituents in the redox-active ligand.…”

Synthesis and characterization of phenanthren-o-iminoquinone complexes of rare earth metals

“…Magnetic measurements revealed that in the complexes of Sc (1) and Dy (5) spines of paramagnetic units are uncoupled while in the complex of Yb (2) there is antiferromagnetic interaction between unpaired electrons on the ligands and Yb 3þ cation. In the complexes I 2 Nd(L) 2 (Et 2 O) 2 (6) and I 2 Dy(L) 2 (Et 2 O) 2 (7), which are formed in the reactions of NdI 2 and DyI 2 with phenanthren-o-iminoquinone, both L ligands coordinate to metal center in quite unusual for iminoquinonates h 1 fashion via O atom. Due to high symmetry of the molecules the X-ray analysis does not allow to distinguish a charged and a neutral ligands.…”

“…The complexes with o-iminoquinones, which are closest electron analogues of o-quinones, are studied in essentially less extent although these ligands also are able to serve as neutral, radical anion (iminosemiquinolate) or dianion (amidophenolate) O,N-chelate ligands. Comprehensive review devoted to 4,6-di-tertbutyl-N-aryl(alkyl)-o-iminobenzoquinonato complexes of transition metals has been published recently [7]. In this review and some original papers one can find the description of homoleptic and heteroleptic iminobenzoquinolates of Zr, V, Cr, Mn [8], Re [9], Fe, Ru [10], Os, Co, Ir, Ni, Pd, Pt, Cu, Ga, Tl, Ge and Sn.…”

Ruthenium Hydride Complexes with Zwitterionic Quinonoid Ligands – Isomer Separation, Structural Properties, Electrochemistry, and Catalysis

“…[2][3][4] The redox noninnocence of such molecules imparts many interesting properties to them. [5][6][7][8][9][10][11][12] Thus, metal complexes of quinonoid ligands have been extensively investigated due to their valence ambiguity and captivating electronic structures, [13][14][15][16][17][18] their engrossing magnetic properties, [19][20][21][22] their use as bridges for molecular and supramolecular systems, [19,[23][24][25][26][27][28][29][30][31][32][33][34][35][36] and in homogeneous catalysis. [37][38][39][40] In recent years, we have developed the chemistry of the potentially antiaromatic zwitterionic quinonoid ligands Q [41][42][43][44] (Scheme 1) and their metal complexes.…”