NEW SELENATO TRIPHENYLTIN (IV) AND TRIMETHYLTIN (IV) DERIVATIVES: SYNTHESIS, INFRARED AND NMR STUDIES

: Five derivatives of general formulae [cation] [SeO4SnR3] (R = Ph, Me) have been studied by infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy. The suggested structures are infinite chains or oligomers, the environment around the tin centre being trans trigonal bipyramidal, the phenyl and methyl substituants occupying equatorial positions, the selenate anion behaving as a bridging bidentate ligand and occupying the apical positions. When cations are involved, supramolecular architectures may be obtained.


INTRODUCTION
The applications of many molecules belonging to organotin family explain the focus of several research groups in this field until nowadays [1 -3].Dealing with selenato complexes according to the Cambridge Database 2016, some X ray structures of selenato complexes have been reported so far: -ethylenediamine (SeO4)2Cd 2H2O with a layered structure, the anion behaving as a bridging bidentate ligand [4]; -piperaziniumZn(SeO4)2 4H2O with a discrete structure, the environment around Zn being octahedral [5].
Some selenato tin (IV) complexes structures have been reported by our group [6 -7].Compared to the data of oxalato complexes, the selenato ones are very scarce.This has prompt us to study the interactions between (R2NH2)2SeO4.xH2O,(R = Bu, Me), and (CyNH3)2SeO4.yH2Owith: SnPh3Cl, SnPh3OH and SnMe3Cl.This has yielded five new derivatives which infrared study has been carried out, then structures suggested on the basis of infrared data.

MATERIALS AND METHODS
A, B and C have been obtained as a white precipitate A or a white powder B-C on mixing: -SeO4(CyNH3)2.2,5H2O with SnPh3OH in 1:1 ratio in methanol for A; -Bu2NH with SeO4H2 and SnPh3Cl in 1:2:2 ratio in ethanol for B; -Me2NH with SeO4H2 and SnPh3OH in 1:2:2 ratio in methanol for C.
D and E are obtained on mixing (Me2NH2)2SeO4 (obtained as a powder on neutralizing SeO4H2 with Me2NH in water-) with SnMe3Cl in 1:1 ratio in methanol (D) or Bu2NH, SeO4H2 and SnMe3Cl in 1:1:1 ratio in methanol (E).
The analytical data have allowed suggesting the following formula (Table 1).

RESULTS AND DISCUSSION
Let us consider the spectroscopic data of the studied compounds.

IR(cm -1 ):
A  The presence of strong bands due to the selenate anion υ3 indicates its involvement in the structures.In all the IR spectra, the broad band around 2900 cm -1 and the strong bands around 1600 cm -1 are indicative of the presence of N-H---O hydrogen bonds.The values of the 119 Sn chemical shift at -126 ppm and -194 ppm for SnPh3 residue containing derivatives are consistent with the presence of a trans coordinated residue according to Holecek et al. [8].Dealing with the two SnMe3 residue containing derivatives the values of the 119 Sn chemical shift at ≈ +43 ppm and ≈ +51 ppm indicate also trans coordinated SnMe3 residue (in the compound (CyNH3)[4-NO2C6H4PO4(SnMe3 )] the 119 Sn NMR shift value in C6D6 is also +43 ppm (br) [9]; pentacoordinated trimethyltin formate HCO2SnMe3 has a chemical shift of +2.5 ppm and +152 ppm for the tetrahedral monomer) [10].
From these data, we can suggest in the solid state, while considering [SnR3SeO4] -(R=Ph, Me) complex-anion, two structures: -an infinite chain one with a bridging selenate, the substituents occupying the equatorial positions as in [11] (Figure 1); -an oligomeric one with a trans trigonal bipyramidal SnR3O2 framework (Figure 2), (We have arbitrary chosen the tetramer while any oligomer works) [12].
While considering the involvement of the cation, a supramolecular architecture as in Cy2NH2C2O4SnMe3 or Bu2NH2C2O4SnMe3 [13] may be obtained.

CONCLUSION
The studied derivatives containing triphenyl and trimethyl residues have an infinite chain or an oligomeric structure in the solid state, the environment around the tin centre being trans trigonal bipyramidal, the selenate acting as a bridging ligand.When the cations involved in hydrogen bonding are considered, supramolecular architectures may be obtained.

Table 1 .
Results of the elemental analyses of compounds A-E.Infrared spectra were recorded on a Bruker Vector 22 spectrometer equipped with a Specac Golden Gate TM ATR device. 119Sn{ 1 H} NMR spectrum was recorded on a Bruker Avance 400 MHz spectrometer with a wide band sensor BBFO. 119Sn{ 1 H} NMR spectra are reported downfield from Me4Sn, as the internal standard.Infrared data are given in cm -1 and chemical shifts (δ in ppm.[IR abbreviations are: (br) broad, (vs) very strong, (s) strong, (m) medium, (sh) shoulder, (w) weak, (vw) very weak].Elemental analyses were performed at the "Institut de Chimie Moléculaire", University of Bourgundy, Dijon-France.H2SeO4 was purchased from Merck Chemicals, Hohenbrunn bei München, Germany while Cy3NH, n-Me2NH, n-Bu2NH, and SnPh3OH, SnR3Cl (R=Ph, Me) were acquired from Sigma-Aldrich Chemie GmbH, Steinheim, Germany and used without any further purification.