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Heterometallic platinum(ii) compounds with β-aminoethylferrocenes: Synthesis, electrochemical behaviour and anticancer activity

A new family of heterometallic compounds 3-6 containing ferrocenyl and platinum(ii) centers has been synthesized by reaction of 1-β- aminoethylferrocene (1) and 1,1′-bis(β-aminoethyl)ferrocene (2) with Pt(ii) precursors. Using K2[PtCl4] as the Pt(ii) source, the cis-square-planar neutral compounds [Fe{η5-C 5H4(CH2)2NH2} 2PtCl2] (3) and [{Fe(η5-C5H 4(CH2)2NH2)(η5-C 5H5)}2PtCl2] (5) were obtained. Reaction of cis-[PtCl2(dmso)2] with 1 and 2 resulted in the displacement of dmso and chloride ligands from the platinum coordination sphere, affording the cationic and neutral compounds [Fe{η5- C5H4(CH2)2NH2} 2Pt(dmso)Cl]Cl (4) and [Fe(η5-C5H 4(CH2)2NH2)(η5-C 5H5)Pt(dmso)Cl2] (6). Compounds 3-6 were thoroughly characterized using multinuclear (1H, 13C, 195Pt) NMR, IR spectroscopy, ESI mass spectrometry and elemental analysis. Single-crystal X-ray analysis of heterometallic 6 confirmed the cis geometry of the molecule and revealed that the platinum atom is held in a perfect square-planar geometry. The electrochemical behaviour of the heterometallic compounds 3-6, which has been examined by cyclic (CV) and square wave (SWV) voltammetries in dichloromethane and dmso solution, is characterized by the reversible one-electron oxidation of the ferrocene moieties. The results of the biological activity studies revealed that the organometallic complex 5 is active against all cell lines with GI50 values in the range 1.7-2.3 μM. When compared to the standard anticancer drug cisplatin, heterotrimetallic 5, possessing two aminoethylferrocenyl units coordinated to the Pt(ii) center, showed a greater activity profile in the colon cancer cell line. Cell cycle studies revealed that the new mixed compound exhibits a mechanism of action different to cisplatin.

Structural influences on the electrochemistry of 1,10-di(hydroxyalkyl) ferrocenes. Structure of [Fe{h5-C5H4eCH(OH)e(CH2)3OH}2]

Abstract A series of 1,1'-di(hydroxyalkyl)ferrocenes, [Fc'{(CH 2)nOH}2], with n = 1 (1), 2 (2), 3 (3) and 4 (4) and Fc' = Fe(η5-C5H4)2, was synthesized. The electrochemistry of the di(hydroxyalkyl)ferrocenes was studied by cyclic voltammetry in CH2Cl2/0.1 M [N nBu4][PF6] utilizing a glassy carbon working electrode. The ferrocenyl group showed reversible electrochemistry with the formal reduction potential, Eo' , inversely proportional to alkyl chain length and approximately 59 mV smaller than those of the corresponding mono(hydroxyalkyl)ferrocenes derivatives [Fc(CH2)mOH] with m = 1 (1m), 2 (2m), 3 (3m), and 4 (4m) and Fc = Fe(η5-C 5H5)(η5-C5H4 -). The tetraalcohol [Fc'{CH(OH)(CH2)3OH} 2], 5, possessing four OH functionalities, two in the terminal positions and two more, one on each of the two α-C relative to the ferrocenyl (Fc' for dialcohols or Fc for monosubstituted derivatives) group, was isolated as a side product during the synthesis of 4. The formal reduction potential of 5 was Eo' = -24 mV vs. FcH/FcH+ and closely approached Eo' of [FcCH(OH)CH3] (Eo' = -11 mV), [Fc'{CH(OH)CH3}2] (-21 mV) and 1 (0.00 mV vs. FcH/ FcH+). The single crystal X-ray structure of the tetraalcohol 5 (Z = 8, orthorhombic, space group Pbca) was also solved.

Influence of a dimetal ion binding ferrocene ligand on the samarium diiodide promoted pinacol coupling reaction

Substantial yield increases have been noted in the use of a di-SmI2 binding ligand for the pinacol coupling of alkyl aldehydes compared to 1:1 complexes of SmI2 and tetraglyme. High diastereoselectivities of ca. 10:1 are also observed for α-substituted alkyl aldehydes in favour of the (±)-isomers.