Organometallic anticancer compounds have emerged as promising alternatives to traditional platinum-based drugs like cisplatin, which suffer from inefficacy against platinum-resistant tumors and severe side effects. Organometallics, defined by their covalent metal-carbon bonds, offer structural diversity, stereochemistry, and kinetic control, making them suitable for medicinal chemistry. They are kinetically stable, lipophilic, and often uncharged, with metal atoms in low oxidation states, enabling new modes of action. Common organometallic classes, such as metallocenes, carbene, and CO ligands, have been applied in medicinal chemistry. Metallocenes, with two cyclopentadienyl ligands, are particularly relevant. Ferrocene, a metallocene, has been studied for its antiproliferative effects, though its toxicity is limited. Ferrocene derivatives, such as ferroquine, have shown antimalarial activity and are in clinical trials. Ferrocene can undergo redox reactions, generating reactive species that may damage DNA. Ferrocene derivatives have also been tested for antitumor activity, with some showing efficacy against cancer cells. Ferrocifens, derivatives of ferrocene linked to tamoxifen, have shown antiestrogenic activity against ER(+) breast cancer cells and are effective against ER(-) cell lines, suggesting a dual mode of action. These compounds may act through redox activation, generating quinone methide intermediates that interact with nucleophiles. Titanocene derivatives, such as titanocene dichloride, have shown antiproliferative activity but faced challenges in clinical trials due to poor solubility and hydrolytic instability. Recent developments include ansa-bridged derivatives with improved stability and activity. Molybdocene derivatives, like molybdenum dichloride, have shown promise as antitumor agents, with binding to DNA and potential for clinical application. Ruthenium-based organometallics, such as RAPTA derivatives, have been explored for their antitumor activity. These compounds, with improved solubility, show lower toxicity than cisplatin and inhibit metastasis in animal models. They may target proteins like cathepsin B and thioredoxin reductase, or inhibit P-glycoprotein, enhancing drug uptake. Some ruthenium complexes also inhibit GST, a key enzyme in detoxification, potentially increasing their cytotoxicity. Osmium-based complexes, though less studied, have shown antitumor activity. Some osmium derivatives, like osmium picolinate, exhibit anticancer activity comparable to carboplatin. These compounds may target telomerase, a crucial enzyme in cancer progression, or interact with DNA through intercalation. Iridium and rhodium complexes, though less studied, have shown DNA intercalation activity. Polypyridyl ligands in these complexesOrganometallic anticancer compounds have emerged as promising alternatives to traditional platinum-based drugs like cisplatin, which suffer from inefficacy against platinum-resistant tumors and severe side effects. Organometallics, defined by their covalent metal-carbon bonds, offer structural diversity, stereochemistry, and kinetic control, making them suitable for medicinal chemistry. They are kinetically stable, lipophilic, and often uncharged, with metal atoms in low oxidation states, enabling new modes of action. Common organometallic classes, such as metallocenes, carbene, and CO ligands, have been applied in medicinal chemistry. Metallocenes, with two cyclopentadienyl ligands, are particularly relevant. Ferrocene, a metallocene, has been studied for its antiproliferative effects, though its toxicity is limited. Ferrocene derivatives, such as ferroquine, have shown antimalarial activity and are in clinical trials. Ferrocene can undergo redox reactions, generating reactive species that may damage DNA. Ferrocene derivatives have also been tested for antitumor activity, with some showing efficacy against cancer cells. Ferrocifens, derivatives of ferrocene linked to tamoxifen, have shown antiestrogenic activity against ER(+) breast cancer cells and are effective against ER(-) cell lines, suggesting a dual mode of action. These compounds may act through redox activation, generating quinone methide intermediates that interact with nucleophiles. Titanocene derivatives, such as titanocene dichloride, have shown antiproliferative activity but faced challenges in clinical trials due to poor solubility and hydrolytic instability. Recent developments include ansa-bridged derivatives with improved stability and activity. Molybdocene derivatives, like molybdenum dichloride, have shown promise as antitumor agents, with binding to DNA and potential for clinical application. Ruthenium-based organometallics, such as RAPTA derivatives, have been explored for their antitumor activity. These compounds, with improved solubility, show lower toxicity than cisplatin and inhibit metastasis in animal models. They may target proteins like cathepsin B and thioredoxin reductase, or inhibit P-glycoprotein, enhancing drug uptake. Some ruthenium complexes also inhibit GST, a key enzyme in detoxification, potentially increasing their cytotoxicity. Osmium-based complexes, though less studied, have shown antitumor activity. Some osmium derivatives, like osmium picolinate, exhibit anticancer activity comparable to carboplatin. These compounds may target telomerase, a crucial enzyme in cancer progression, or interact with DNA through intercalation. Iridium and rhodium complexes, though less studied, have shown DNA intercalation activity. Polypyridyl ligands in these complexes