Synthesis of monoorganotin(IV) chloride complexes of cis-1,2-bis(diphenylphosphino)ethylene: Solution and solid state structures

Abstract

Organotin(IV) complexes of the type [RSnCl 3 (cis-Ph 2 PCH@CHPPh 2 )] [R = Me (1), n Bu (2), Ph (3)] were prepared by the reaction of RSnCl 3 with the rigid bisphosphine ligand, cis-1,2-bis(diphenylphosphino)ethylene in dichloromethane. The complexes have been characterized both in solution and the solid state. Low temperature 31 P and 119 Sn NMR studies indicate two different phosphorus environments. The crystal structures indicate a weak but chelating mode of coordination of the two phosphorus atoms to tin, leading to a distorted octahedral geometry. In solution the complexes 1-3 undergo a redistribution reaction to form [SnCl 4 (cis-Ph 2 PCH@CHPPh 2 )] (4) as one of the products. In order to confirm the redistribution, complex 4 has been prepared separately and characterized both structurally and spectrally.

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

“…A different synthetic approach involved the reaction of tin powder with PR 3 X 2 (R = n Pr, X = I; R 3 = Ph, Ph 2 Me or PhMe 2 , X = Br or I) in diethyl ether [283,293], which produced the first structurally authenticated phosphine adduct of tin(IV) iodide, trans-[SnI 4 (P n NMR data has also been reported for many tin(IV) complexes and some typical examples are shown in Table 12 [281,287,291,292,[296][297][298]. The 119 Sn chemical shifts are surprisingly similar for corresponding complexes of SnF 4 and SnCl 4 , but those of SnBr 4 and SnI 4 show much more deshielded resonances.…”

“…Diphosphine complexes are usually six-coordinate monomers with a cis-geometry (Table 11); typically the Sn-X transX bonds are longer than Sn-X transP , showing the dominant Sn-X bonding [281,286,287,291] (Fig. 53) [281].…”

“…Organotin halides SnR 4−n X n (n = 3 − 1) also form phosphine adducts [289][290][291]298,[301][302][303][304]. The Lewis acidity falls with increase in the number of R groups, and is less than that of SnX 4 ; as a result both five-and six-coordinate complexes are formed depending upon the phosphine and the organotin species involved.…”

“…The Ph 2 P(CH 2 ) n PPh 2 (n = 1 or 2) complexes of SnPh 2 X 2 (X = Cl or Br) are clearly five-coordinate in solution, with fast exchange occurring between the free and coordinated phosphine groups on the NMR time-scale [290]. However, using more rigid diphosphines such as cis-Ph 2 PCH = CHPPh 2 , or the chiral o-C 6 H 4 (PPhMe) 2 , produces complexes that are six-coordinate both in the solid state and in solution at low temperatures [290,291]. Disproportionation of RSnX 3 into R 2 SnX 2 and SnX 4 upon reaction with phosphines was also observed in some systems [290,291,302].…”

“…However, using more rigid diphosphines such as cis-Ph 2 PCH = CHPPh 2 , or the chiral o-C 6 H 4 (PPhMe) 2 , produces complexes that are six-coordinate both in the solid state and in solution at low temperatures [290,291]. Disproportionation of RSnX 3 into R 2 SnX 2 and SnX 4 upon reaction with phosphines was also observed in some systems [290,291,302]. Intramolecular coordination of P-functionalised organotin halides produces more stable complexes [305][306][307][308].…”