Studies of hypervalent organotin complexes and organotin clusters

(119)Sn, (31)P and (13)C variable temperature NMR spectroscopies have been used to examine the effective coordination spheres in solution of a series of hypervalent organotin(IV) dithiolate compounds RnSnXm(S-S)4-n-m where R = Ph, Me, nBu, tBu; X = Cl, Br; (S-S) = S2CNR'2, S2COR', S2P(OR')2 (R' = Me, Et, iPr) and n = 1, 2, 3; m = 0,1,2. Stereochemical nonrigidity is a common phenomenon found for these hypervalent compounds. On the basis of heteronuclear NMR data and X-ray crystallographic data, dynamic behaviors of these hypervalent compounds have been established. The system of hypervalent organotin(IV) fluoride complexes has also been investigated by variable temperature heteronuclear NMR techniques. A series of monomeric pentacoordinate complexes [RnSnC1mF5-n-m]-(R = Ph, Me, nBu, tBu; n = 2, 3; m - 0, 1, 2, 3) and dimeric complexes [(Me3SnX)F(Me3SnX')]- (X = F, Cl; X' = F, Cl) and hexacoordinate complexes [RnSnClmF6-n.m]2- (R = Ph, Me, nBu; n = 1, 2; m = (X 1, 2, 3,4) are identified in solution. The fluoride is of higer affinite to tin than the chloride. The stereochemistry and dynamic behavior of these complexes in solution has been studied. Fluoride ion may induce phenyl group disproportionation of phenyhin(IV) compounds. It is also found that in pentacoordinate diorganotin complexes, such as [Ph2SnCl2F]- and [Ph2SnClF2]- fluorine can be less apicophilic than chlorine. Studies of stereochemistry and dynamic behavior of bi-functional Lewis acid bis(haloorganosiannes) have also been carried out. The bis(haloorganostannes) exhibit strong chelate ability towards halide, with high selectivity on fluoride, forming heterocyclic chelating rings, the stability of which depend on the ring size. In further exploration of the Lewis acidity of organotin(IV) halides, complexation of organotin(IV) halides with bis(tertiary phosphinc) ligands has been studied by 119Sn and 31P NMR spectroscopy and X-ray crystallography. The phenyl group disproportionation is often observed in the complexation reaction. Furthermore, organotin(IV) clusters such as [(RSn)12O14(OH)6]Cl2-2H2O (R = iPr, nBu) have been successfully prepared by base hydrolysis of RSnCl3. These clusters contain 12 tin atoms in one molecule and the cores of the clusters are dications. Other organotin clusters such as [nBuSn(O)O2CCH3]6 and [(nBuSn(OH)O2PPh2)3][O2PPh2) are readily formed by reaction of the 12-tin-atom cluster with an appropriate acid. The reactivity of and interconversion between organotin(FV) clusters have also been studied.

Novel organotin and organotellurium complexes : building blocks for new materials?

The research produced a series of novel oranotin and organotellurium compounds that are potential building blocks for new materials. In particular, one carbonate cluster has practical applications in the fixation and recovery of carbon dioxide gas from the atmosphere.

Perceptive variation of carboxylate ligand and probing the influence of substitution pattern on the structure of mono- and di-butylstannoxane complexes

By reacting 2- and 3-aminobenzoic acids (HL1 and HL2, respectively), as well as 2-, 3- and 4-((E)-2-[4-(dimethylamino)phenyl]diazenyl)benzoic acids (HL3, HL4 and HL5, in this order) with a n-butyltin(IV) source [ n BuSn(O)OH or n Bu2SnO], the drum-type butylstannoxane complexes of general composition [ n Bu6Sn6O6(L n )6] [L n =L1 (1), L2 (2) and L3 (3)] and the ladder-type compounds [ n Bu8Sn4O2(L n )4] [L n =L3 (5), L4 (6) and L5 (7)] were obtained and fully characterized. By reacting 1 with 2-((E)-[4-(dimethylamino)benzylidene]amino)benzoic acid (HL6), a co-crystal (4) was achieved which comprises the metal complex aggregate found in 1 and the neutral HL6 molecule. The solution properties of the compounds were assessed from 1H and 13C NMR studies and, for the metal complexes, also from 119Sn NMR. The molecular structures of 1, 2, 4-7 were confirmed by single-crystal X-ray diffraction. Compounds 1-3 and the complex moiety of 4 display hexameric Sn6O6 clusters with drum-like structures, but 5-7 reveal Sn4O2 cores with ladder-type structural motifs. Besides the observed relationship between the ligand N-functional group and obtained (drum- or ladder-type) assemblies, the relative position of the carboxylate group in the ligand itself influences its coplanarity.