Preparation and properties of cyclic and open-chain Sb/N-donor ligands

Abstract

The preparations of both open-chain and cyclic mixed-donor Sb/N ligands, MeN(CH2-2-C6H4)2SbMe (1), MeN(CH2-2-C6H4SbMe2)2 (2), CH2{CH2N(Me)CH2-2-C6H4SbMe2}2 (3) and CH2{CH2N(Me)CH2-2-C6H4}2SbMe (4), are described via reaction of chlorostibines with dilithio-reagents, and their spectroscopic properties established. Air-stable stibonium derivatives of (3) and (4) have been isolated by treatment of the compounds with excess MeI, which leads to quaternisation at the Sb atoms exclusively. A crystal structure of a bis(stibonium) derivative of (3), [CH2{CH2N(Me)CH2-2-C6H4SbMe3}2]I2, reveals hypervalency at Sb through long-range Sb...N interactions (ca. 2.87 A), giving pseudo-five-membered rings fused to the aromatic rings, and distorted trigonal bipyramidal coordination at Sb. The coordinating properties of compounds (1) to (4) have been investigated through their reactions with Cu(I), Mn(I), Mo(0) and Pt(IV) reagents, and for (1) and (4) by reaction with Fe(0), giving [Fe(CO)4(L)]. The spectroscopic data (IR, 1H, 13C{1H}, 55Mn, 63Cu, 95Mo and 195Pt NMR), mass spectrometry and microanalyses for this series of complexes confirm that coordination occurs via the Sb donor atoms in all cases, with N-coordination only present in fac-[Mn(CO)3(2)](CF3SO3). Crystal structures of [Cu(2)2]BF4, [Mo(CO)4(2)] and [PtMe3I(2)] confirm the coordination modes, showing (2) functioning as a wide-angle bidentate distibine. The structures also show the amine N-donor atoms in the complexes are involved in a hypervalent SbN interaction (ca. 3.0 A) with one of the coordinated Sb atoms in each ligand, leading to significant differences in the conformations of the carbon backbones linking the Sb and N atoms. Reaction of Na3[RhCl6].12H2O with one mol equiv. of (2), (3) or (4) leads to the bis-ligand complex [RhCl2(2)2]Cl and the 1 : 1 Rh : L complexes [RhCl2(3)]Cl and [RhCl3(4)], both of which involve coordination via the Sb and N donor atoms.

Hybrid dibismuthines and distibines as ligands towards transition metal carbonyls

“…The ready formation of [M(CO) 4 (hybrid distibine)] complexes was unexpected since the chelate rings formed are large, 10- 1 to 4). The coordination environments in [M(CO) 4 {MeN(CH 2 -2-C 6 H 4 SbMe 2 ) 2 }], are similar to that in the molybdenum analogue reported earlier, 9 showing a near to octahedral geometry and M-C transSb shorter than M-C transCO . Notably, the tungsten complex shows one hypervalent N ◊ ◊ ◊ Sb interaction to antimony (Sb2 ◊ ◊ ◊ N = 2.997(3) A ˚).…”

Neutral organoantimony(III) and organobismuth(III) ligands as acceptors in transition metal complexes – Role of substituents and co-ligands

“…19,20,21 These were originally of interest as ligands which could present a mixed donor set to a transition metal fragment, allowing examination of stibine coordination within a more robust, chelating ligand framework. As part of this work, complexes with low-valent metal carbonyls were pursued as appropriate acceptors for the soft stibine donors.…”

Synthesis, Structure and Applications of Hypervalent Organoantimony Compounds Having Intramolecular E→Sb (E = N, O, S) Coordinations

“…Compound 98 was obtained by dilithiation of bis(2-bromobenzyl) sulfide with n-BuLi followed by subsequent reaction with Me 2 SbCl (Scheme 31). Levason and co-workers also reported the application of distibine 98 as Sb donor ligand [38,80,83]. …”

“…In 2004 [80,83], and (iii) chelating tridentate (Sb 2 N-or Sb 2 S-coordinated) such as [Mn(CO) 3 (85)] (123) (Fig. 10), [Cr(CO) 3 (98)] (124) and [Mn(CO) 3 (98)] (125) [80,83].…”

“…They were prepared by dilithiation of the corresponding precursor with n-BuLi, followed by subsequent reaction with Me 2 SbCl (Scheme 26), and their application as Sb donor ligand has been reported [38,80].…”