Design of hydroxyl- and thioether-functionalized iron-platinum dimetallacyclopentenone complexes. Crystal and electronic structures, Hirshfeld and docking analyses and anticancer activity evaluated by in silico simulation

Abstract

A series of metal-metal bonded iron-platinum heterobimetallic complexes has been prepared by carbon-carbon coupling of [(OC)3Fe(µ-C=O)(µ-dppm)Pt(PPh3)] (1) (dppm = Ph2PCH2PPh2) with the terminal alkynols 4-pentyn-1-ol, 4-pentyn-2-ol and the internal thioether-functionalized alkyne 1,4-bis(p-tolylthio)but-2-yne. The resulting dimetallacyclopentenones [(OC)2Fe(µ-dppm){µ-C(=O)C((CH2)3OH)=CH}Pt(PPh3)] (2a) and [(OC)2Fe(µ-dppm){µ-C(=O)C(CH2CHOHCH3)=CH}Pt(PPh3)] (2b) featuring intramolecular hydrogen O-H···O=C bonding have been structurally characterized, as well as [(OC)2Fe(µ-dppm){µ-C(=O)C(CH2S(p-tolyl))=C(CH2S(p-tolyl))}Pt(PPh3)] (2c). NMR studies reveal that coupling of 1 with HCC-CH2CH2CH2OH yields initially the kinetic isomer [(OC)2Fe(µ-dppm){µ-C(=O)C(H)=C((CH2)3OH)}Pt(PPh3)] (2a’), which upon heating converts quantitatively to the thermodynamic isomer 2a. Furthermore, the molecular structures of series 2 were investigated by means of Hirshfeld surface analyses. As targets for a bioinformatic study, molecular docking studies were applied to the complexes 2 and revealed the occurrence of intermolecular interactions with four different protein residues associated with breast (1hk7 and 3eqm) and prostate cancer (2q7k and 2ax6). According to the docking results, this family of complexes displays better activity on prostate cancer proteins rather than breast cancer ones. The molecular structures of compounds 2 were also optimized using DFT quantum chemical calculations. The large band gap implies low reactivity and good stability of these complexes.