New palladium complexes with bis(8-thiotheophylline)alkane derivatives

Water-Soluble Cp Ruthenium Complex Containing 1,3,5-Triaza-7-phosphaadamantane and 8-Thiotheophylline Derivatives: Synthesis, Characterization, and Antiproliferative Activity

“…The 1 H NMR signals of 4 , 5 , and 6 , and 10 , 11 , and 12 were assigned by the use of 1 H, 1 H-2D COSY NMR and were found to be similar to those of the corresponding mononuclear analogues 1 − 3 and 7 − 9 , plus the signals of the linking CH 2 chain of the bis-thiopurines. The MBTTH 2 S-CH 2 -S group in 10 was found as a broad singlet at 4.62 ppm, which is in the range to that found for the complexes cis -[{PtCl(PPh 3 ) 2 } 2 (μ-MBTT-κ N7,N7′ )] (5.0 ppm), cis -[{Pt(PTA) 2 } 2 (μ-Cl)(μ-MBTT-κ N7,N7′ )]Cl (4.21 ppm), and trans -[{PdCl(PPh 3 ) 2 } 2 (μ-MBTT-κ N7,N7′ )] (4.15 ppm) . Nevertheless, in the 1 H NMR spectrum of 4 , it was not possible to locate the S-CH 2 -S hydrogen atoms, whose signal is probably overlapped to the H 2 O residue signal.…”

“…The 13 C{ 1 H} NMR was also in agreement with the proposed composition for 2 . The signal for the S-CH 3 arises at 14.15 ppm that is close to that for 8-MTTH (14.00 ppm). , The 31 P{ 1 H} NMR spectrum showed a single signal at −25.19 ppm due to phosphorus-coordinated PTA. Therefore, the spectroscopic data for 2 are similar to the corresponding found in previously reported 8-MTT − complexes where the thiopurine is invariably coordinated by the imidazolic N7.…”

“…The 13 C{ 1 H} NMR spectrum is in agreement with the proposed composition: signals for N1-CH 3(8-TTH) and N3-CH 3(8-TTH) thiopurine methyl groups and for the Cp ligand are observed at 27.97 ppm, 30.19 ppm, and 79.49 ppm, respectively. The chemical shift for the C8−S carbon atom arises at 158.89 ppm, at higher field than that found for 8-TTH 2 in the same solvent (164.83 ppm). , Unfortunately the chemical shift of C8−S has not been reported for analogue complexes. The presence of coordinated PTA is also supported, in the 31 P{ 1 H} NMR spectrum, by a singlet at −22.97 ppm whose chemical shift is similar to that observed for the PTA ligand in [RuClCp(PTA) 2 ] (−23.6 ppm) …”

“…The spectroscopic data suggested that the structure of 2 was similar to other previously reported 8-MTT − metal complexes. Its IR spectrum showed no ν(N−H) absorption band but absorptions for ν(C6O + C2O) (1677, 1628 cm −1 ) and ν(CC + CN) (1519 cm −1 ) in the range found for 8-MTT − complexes in which the purine is bonded to the metal by the imidazolic N7 atom. ,,, 1 H, 13 C, and 31 P NMR spectra of 2 in CDCl 3 showed a single pattern, excluding the formation of isomers. The 1 H NMR displayed the expected signals for a Cp, two PTA, and an 8-MTT − .…”

“…All reactions and manipulations were routinely performed under a dry nitrogen atmosphere by using standard Schlenk-tube techniques. The compounds PTA, [RuClCp(PTA) 2 ], and [RuClCp(PPh 3 )(PTA)] were prepared as described in the literature. ,, Ligands 8-thiotheophylline (8-TTH 2 ), 8-methylthiotheophylline (8-MTTH), 8-benzylthiotheophylline (8-BzTTH), bis( S -8-thiotheophylline)methane (MBTTH 2 ), 1,2-bis( S -8-thiotheophylline)ethane (EBTTH 2 ), 1,3-bis( S -8-thiotheophylline)propane (PBTTH 2 ) have been prepared following the procedure described by literature methods. , 1 H, 31 P{ 1 H} NMR, and 13 C{ 1 H} NMR spectra were recorded on a Bruker DRX300 spectrometer operating at 300.13 MHz ( 1 H), 121.49 MHz ( 31 P), and 75.47 MHz ( 13 C), respectively. Peak positions are relative to tetramethylsilane and were calibrated against the residual solvent resonance ( 1 H) or the deuterated solvent multiplet ( 13 C).…”