X-Ray and NMR study of tetra-and penta-coordinated stanoxanes derived from trans -cinnamic acid

We report a new stanoxano polymer structure 1 , derived from trans -cinnamic acid and triphenyltin chloride. X-ray structure shows a carboxylated bridge between two tin groups in a linear rearrangement, the pack in the unit cell is conformed by non-classical interactions (D-H···A), because the presence of aromatic rings were observed C-H··· π interacting in a supramolecular structure. In solution the compound 1 was compared with tributhyltin-trans - cinnamete 2 , the NMR data shown penta-and tetra-coordinated compounds respectively, both compounds were dissolved in DMSO-d 6 and the tin geometry goes from penta-to hexa-coordinated for 1 and from tretracoordinated to pentacoordinated for 2


Introduction
trans-Cinnamic acid is found as structural unit in anti-oxidant compounds, in some drugs and balsams. 1 It is a cinnamaldehyde derivative that comes from cinnamon, in the last ten years the cinnamic acid and its derivatives were found to be anti-bacterials, anti-fungals, and are important in the synthesis of cumarinic derivatives. 2The interest in organotin compounds is because their biological activity, 3 so the understanding of the structural base needs special attention of the electronic effects and coordination number.It is well known the potential activity of tin compounds as anti-cancer and anti-tumor agents 4 and the relationship between the organic fragment and organometallic tin plays an important role in some biological aspects, for example as nematicidal and insecticidal. 5The spectroscopic study of tetra-and pentacoordinated stanoxanes derived from trans-cinnamic acid; base their importance on their organic structure, because they are models of NMR and X-ray diffraction and biological assays.

Results and Discussions
Compounds 1 and 2 were obtained following the procedure shown in the Scheme 1, this is a variation of the Gielen 6 method (see experimental section), and we use benzene as solvent because we need to avoid solvent coordination.Both compounds which are white solids, were obtained in good yields and they are stable to air and moisture.Then the compounds 1 and 2 were dissolved in DMSO-d 6 to get compounds 3 and 4 also were analysed spectroscopically.Scheme 1. Syntheses of complexes 1 and 2, and numerbering system used to analyse the spectrum.

NMR Analyses
All compounds have good spectra; and were corroborated with COSY and HETCOR experiments, tables 1 and 2, chemical shifts are characteristics of the respective coordination number in solution. 7The 119 Sn values in -112.0 for compound 1 with a ∆δ = -64 ppm with respect to the starting material Ph 3 SnCl 8 and in +110.9 for compound 2 with a ∆δ = -30 ppm with respect to the starting material Ph 3 SnCl, 9 are indicative of penta-and tetra-coordinated compounds, respectively.Danutsh Because the trans-cinnamic acid and phenyl nuclei are not modified, the 13 C chemical shifts have not meaningful changes.The C7 position goes at lower frequency from starting material I to 1 (∆δ=2.4), 2 (∆δ=3.4), 3 (∆δ=5.5)and 4 (∆δ=6.0), the same behaviour was observed for C9 position but the ∆δ values are smaller (0.6, 0.6, 2.4, 2.3, respectively) than C7.The C8 signal is shifted to higher frequency from that in the starting material I to 1 (∆δ=2.3), 2 (∆δ=3), 3 (∆δ=56.4)and 4 (∆δ=6.6).All those changes are indicative in the compounds 1 and 2 of the presence of tin fragment; meanwhile the biggest changes for compounds 3 and 4 are indicative of ARKAT USA, Inc.
the high coordination number in the tin atom.The coupling constants n J( 13 C-117/119 Sn) that are in brackets in Table 1 correspond to assigned atom and all of them are indicative of the tin geometry, according to the literature. 13he 1 H NMR for compounds 1-4 are summarized in Table 2, the H7 signals for different compounds are shifted to lower frequency than the starting material I, while H8 almost does not have changes.The rest of the protons have not important changes.The trans-coupling constant 3 J( 1 H7-1 H8) was confirmed in all compounds around 16 Hz for phenyltin-derivatives and 15 Hz for butyltin-derivatives, all of them are close to starting material I.

X-Ray analyses
Compound 1 crystallizes in the monoclinic space group P2 1 /n from chloroform, the crystal data, selected bonds and angles are given in Tables 3, 4. Figure 1 shows the ORTEP diagram, three phenyl groups in a equatorial position and trans-cinnamic acid is occupying axial position, in the opposite site, from this, an empty space shows coordination to the tin atom by other electron donor group.

Conclusions
From spectroscopy data we found different tin compounds: for 1 (penta-coordinated, 119 Sn = -112.0),for 2 (tetra-coordinated, 119 Sn = + 109.9), for 3 (hexa-coordinated, 119 Sn = -260.2) and for 4 (penta-coordinated 119 Sn = -20.0).The structure of 1 was corroborated by X-ray diffraction, we found a polymeric triphenyltin-trans-cinnamete structure, because the acidity of tin center, causes that the carboxylic group in the trans-cinnamic acid acts as a bridge between two tin groups, the lattice are govern by non classical intra-and inter-molecular interactions (D-H⋅⋅⋅π).Compound 3 and 4 were obtained dissolving 1 and 2 in DMSO-d 6 , the chemical shift of 119 Sn shows signals at lower frequency than the starting materials, showing the acidity of the tin center.
performed in Crystals 18 program.Graphics were performed in ORTEP 19 and Mercury 20 programs.

Figure 1 .
Figure 1.ORTEP diagram of compound 1, showing the atom-numbering scheme and displacements ellipsoids at the 50 % probability, hydrogen atoms are omitted for clarity.

Figure 4 .
Figure 4. Supramolecular structure of compound 1, packing is controlled by non-classical interactions, view along b exe.

and 4, the
Ph 3 SnOC(O)Ph with 119 Sn = -110 ppm and tributyltin compound by Davies 8 et al. of Bu 3 SnOC(O)C 6 H 4 OCOMe-2 with 119 Sn = + 115 ppm, both compounds corroborate the assignment of compounds 1 and 2. The acidity of 1 and 2 were evident when we added DMSO-d 6 to obtain compounds 3 10et al. reported the 119 Sn chemical shift of Me 3 Sn-m-Metrans-cinnamate with 119 Sn = + 129 ppm, that is close in value to compound 2. A related carboxylic triphenyltin compound was reported by Holeček 11 et al.

Table 3 .
The crystal data of compound 1

Table 4 .
Selected bond distances and angles of compound 1

-cinnamate 1 [(C 9 H 7 O 2 )Sn(C 6 H 5 ) 3 ]
. A solution of 0.5 g (3.3 mmol) of I and 0.4702 ml (0.3414 gr, 3.374 mmol) of triethylamine in 20 ml of benzene was prepared under continue stirring.A separated solution was prepared by addition of 1.2515 gr (3.3 mmol) triphenyltin chloride and 0.4702 ml (0.3414 gr, 3.374 mmol) of triethylamine in 20 ml of benzene.Then the solutions were mixed under strong and continue stirring, the reaction mixture was refluxed by 3 h after that the solution was stirred by 3 h at room temperature.The mixture of reaction was filtered off and the solvent was removed at low pressure, the white solid was washed two times with benzene and was crystallized with chloroform.The white solid, 1.(FAB+): 267 (C 9 H 7 O 2 Sn, 10%), 351 (C 18 H 15 Sn, 100%), 421 (C 21 H 17 O 2 Sn, 93 %), 497 (C 27 H 2 O 2 Sn, 5 %).Anal.Calc.for C 27 H 22 O 2 Sn: C, 65.23; H, 4.46.