Intramolecularly coordinated organoantimony(III) carboxylates

Structural study on the organoantimony(III) NCN – Chelated compounds [2,6-(Me2NCH2)2C6H3]SbX2 – Influence of the polar group X

“…IR spectra of 2 in CHCl 3 solution revealed only one band for antisymmetric and symmetric CO 2 stretching proving equivalently bonded carboxylic groups. The Dm between the antisymmetric and symmetric CO 2 stretching (357 cm À1 ) proves unidentate coordination of both acetates [18,21] (similar situation was observed in the solid sample, proving similar coordination of the carboxylates in both phases). The 1 H NMR spectra revealed broaden set of signals at 300 K, that is resolved to an AX pattern for the NCH 2 and two signals in 1:1 integral ratio for the N(CH 3 ) 2 groups at 230 K. These findings correspond to a fluxional behaviour of the coordination of the ligand at 300 K, which is slowed down upon cooling resulting to the cis coordination of both CH 2 N(CH 3 ) 2 pendant arms of the ligand (trans position of these donor groups gives rise to only singlet resonances for both NCH 2 and N(CH 3 ) 2 groups in the case of the compound 3 vide infra).…”

“…In contrast to these findings, in the case of the OCO chelated analogue one of the trifluoroacetates was coordinated in the bidenate fashion [18]. Both nitrogen donor atoms of the ligand L in 3 are coordinated to the central atom through intramolecular interaction (Sb(1)-N(1) 2.440(4) and Sb(1)-N(2) 2.373(4) Å) mutually in pseudo trans positions with the angle N(1)-Sb(1)-N(2) 149.54 (14)°.…”

“…The structure of 2 in solution can be, thus, described as a trigonal pyramid formed by the antimony atom ipso carbon atom and two oxygen atoms (from acetates), which is cis coordinated (bi-capped) by two nitrogen donor atoms coming from the ligand [22]. Very similar situation has been recently observed in the case of the OCO chelated analogue, whose molecular structure was determined by the X-ray diffraction technique [18].…”

Studies on bismuth carboxylates—synthesis and characterization of a new structural form of bismuth(III) dipicolinate

“…The biological activity of these compounds, however, is assumed to involve the initial reduction of Sb(V) to Sb(III). Details on the structures of these compounds are still elusive, although in the case of bismuth, reasonable models like [Bi 38 O 44 (Hsal) 26 (Me 2 CO) 16 (H 2 O) 2 ]·(Me 2 CO) 4 and [Bi 9 O 7 (Hsal) 13 (Me 2 CO) 5 ]·(Me 2 CO) 1.5 are available (figure 1). 3 Many of the structurally characterized bismuth subcitrates have the core, [Bi 6 O 4 (OH) 4 ] 6+ .…”

“…Structural studies on antimony(III) carboxylates are rather limited when compared to those on bismuth. 4 However, there are a number of structurally characterized * For correspondence Sb(V) carboxylates/phosphinates including those from our research group (e.g., 1-3). 5 We have embarked on a plan to extend this chemistry in the context of pharmaceutically active bismuth and antimony carboxylates.…”