Developments in the coordination chemistry of stibine ligands

Coordination chemistry of the main group elements with phosphine, arsine and stibine ligands

“…The only recent examples are [(PR 3 ) 2 Pb{Cr(CO) 5 } 2 ] (R = Me, Et or n Bu) which contain fourcoordinate lead [320]. All three were structurally characterised with the Pb-P bond increasing in length from 2.76Å (R = Me) to 2.85Å (R = n Bu).…”

“…The weaker donor stibines have a more restricted chemistry and relatively few bismuthine complexes are known [5]. These Group 15 neutral donor ligands are described in standard texts as -acids or -donor -acceptor ligands, which bond to d-block metals by -donation of the lone pair on the pnictogen (E) centre, supplemented in many cases by -acceptance of d-electron density into E-C *-(or a combination of E-C *-and empty E d-) orbitals.…”

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

“…As discussed above, species of the form SbR3 (triorganostibines) are generally considered as Lewis bases, and their donor behaviour towards transition metals has been well studied, 5,6,8 though the number of stibine complexes still represents a tiny fraction compared to number of phosphine complexes reported. Less well explored is their Lewis acidic character, which, while weak, allows the formation of long intra-or inter-molecular contacts, often referred to as 'hypervalent' interactions,  van der Waals radii for Sb and Bi are 2.47 and 2.54 Å, respectively.…”

“…1,[5][6][7][8] Halostibines and halobismuthines are expected to fall between the two extremes of Lewis acid and Lewis base behaviour due to the presence of both substituent types. Examples of these compounds acting as Lewis acids are rather rare and, unsurprisingly, complexes of ERX2, bearing two electronegative halide substituents, with other neutral ligands tend to be more prevalent than those with ER2X.…”

“…The coordination chemistry of triorgano-stibine and -bismuthine ligands has been reviewed previously, 5,6,7,8 whilst Braunschweig and co-workers have reviewed the synthesis, structure and properties of complexes containing a transition metal-bismuth bond. 9 Much of work relevant to the present article is quite disparate and has emerged only over the last decade and is not reviewed elsewhere.…”