Stereochemical nonrigidity and ligand dynamics in hypervalent tin(IV) compounds. Heteronuclear NMR and crystallographic studies of triorganoyltin(IV) and diorganoyltin(IV) complexes with dithiolate ligands

Abstract

Tin-1 19, phosphorus-3 1, and carbon-13 NMR data have been used to examine the effective coordination spheres in dichloromethane solution of a series of triorganoyl-and diorganoyltin(1V) dithiolate compounds R3Sn(SS) (where R = Ph, Me) and R2Sn(SS)2 (where R = Ph, Me, "Bu, 'Bu) for S S = SzCNEt2, S2COEt, and S2P(OEt)2 as well as diorganoyltin(1V) dithiolate halide complexes R*SnX(SS) (R = Ph; X = C1, Br; and R = Me, "Bu, 'Bu; X = Cl). For R3Sn(SS) compounds only dithiocarbamate ( S S = SzCNEt2) seems to behave as an actual bidentate sulfur ligand whereas for other systems intramolecular monodentate-bidentate dithiolate exchange is rapid at room temperature, with the equilibrium favoring bidentate sulfur coordination at low temperature for some systems. The effectiveness of dithiolates as chelate ligands becomes more evident in R2Sn(SS)2 and in R2SnCl(SS) derivatives. There is evidence that the dithiocarbamate ligand in Ph2SnC1(S2CNEtz) is bidentate and that the compound is five coordinate and stereochemically rigid in solution at -100 OC. A comparison of solid-state and solution NMR data indicates that in solution the dithiocarbamate ligand acts as a bidentate sulfur donor in M~~S I I ( S~C N E~~)~ but only as a monodentate donor in ' B U~S~( S~C N E~~)~.The crystal structure of ' B U~S~( S~C N E~~)~ has been determined and is almost identical to the known structure of Me2Sn(SzCNEt2)2. In the structure of ' B U~S~( S~C N E~~)~ the S n S bond lengths are asymmetric (2.5 and 2.9 A), but the overall stereochemistry suggests that the role of the two sulfur atoms of each chelate may be easily interchanged, possibly through a pseudooctahedral intermediate having the chelates symmetrically displaced. There is no evidence for any steric stress resulting from the tBu groups, and consequently electronic influences are invoked to explain observed differences in stereochemical nonrigidity for various hypervalent tin(1V) systems in solution. The crystal structures of tBu2SnC1(S2CNEt2) and Ph2SnCl(S2-CNEt2) have also been determined, and in each case there is asymmetric coordination by the sulfur atoms of the dithiolate ligand to tin.

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

“…The 119 Sn NMR spectra at lower temperatures exhibit six lines for 1 and 3 whereas 2 shows a four line pattern. The chemical shifts (Table 1) are in the range reported previously for six coordinate geometry around tin [26].…”

Synthesis and characterization of organotin complexes with dithiocarbamates and crystal structures of (4‐NCC6H4CH2)2Sn(S2CNEt2)2 and (2‐ClC6H4CH2)2 Sn(Cl)S2CNBz2

“…2). The contact of Sn(1) and S(2)# is significantly longer than the sum of the covalent radii of tin and sulfur atoms (2.42Å) and less than the sum of the van der Waals radii for these atoms (4.0Å), 44,45 and the S-S bond length is within the sum of the van der Waals radii of two sulfur atoms (3.70Å). 46 From this, the structure of complex 1 is best described as a weakly bridged dimer (see Fig.…”

Tetraphenylphosphonium and Tris (1.10-PHENANTHROLINE) Iron(ii) Salts of Anionic Complexes of Dibutyltin(iv) With Dithiocarbimates: Synthesis, Characterization and Antifungal Activity

“…5 Como este é normalmente um sinal de muito pequena intensidade, não foi possível observá-lo nos Sn dos compostos 1 a 3 observaram--se dois sinais, um mais intenso na faixa de δ 128 a 129 e outro de menor intensidade entre δ -215 e -225, indicando números de coordenação, quatro e cinco, respectivamente. 21 Porém, um sinal na faixa δ -215 e -225 também pode indicar uma hexacoordenação em que dois ligantes estão mais fracamente ligados (os átomos de nitrogênio) como já foi observado em compostos semelhantes. 5,22 Em solução essas interações podem ser quebradas resultando em um equilíbrio entre espécies hexa e tetracoordenadas (Figura 6).…”