Search Results (52)

A novel multidentate ligand with an O,N,O-tridentate ligand moiety and an N-heterocyclic carbene (NHC) was synthesized. Its palladium complex, in which the NHC part coordinates to the palladium atom, was synthesized and structurally characterized. The O,N,O-part coordinated to an early transition metal such as titanium. The Ti-Pd heterobimetallic complex was observed in solution. Full article

Nature-inspired ligands, including natural product scaffolds and bio-inspired motifs, have emerged as an important source for the development of gold(I) complexes with promising preclinical anticancer activity. This review focuses on structurally characterised gold(I) complexes derived from these ligands, emphasising how ligand structure and gold coordination influence the biological activity. This paper covers the synthesis of nature-inspired gold(I) complexes, alkynyl, N-heterocyclic carbene (NHC), heteroatom-donor, and heterobimetallic complexes, which collectively contribute to enhanced cytotoxicity, stability, and mechanistic diversity. By focusing on these nature-inspired gold(I) complexes, this review provides a concise structure–activity perspective and outlines future opportunities for rational design in anticancer research. Full article

Heterobimetallic iron–group 9 carbonyl cations, FeM(CO)_n⁺ (M = Rh, Ir; n = 9–11), were generated in the gas phase via pulsed laser vaporization within a supersonic expansion and characterized by infrared photodissociation spectroscopy in the carbonyl stretching region. By combining experimental spectra with density functional theory simulations, the geometric and electronic structures of these clusters were unambiguously assigned. Mass spectrometry and photodissociation results identified FeM(CO)₉⁺ as the saturated species for M = Rh and Ir, in contrast to the lighter cobalt analog FeCo(CO)₈⁺. The FeM(CO)₉⁺ cations adopt a C_4v-symmetric singlet ground-state structure with all carbonyl ligands terminally bound, corresponding to a (OC)₅Fe–M(CO)₄ configuration. These complexes can be formally described as combination products of the stable neutral Fe(CO)₅ and cationic M(CO)₄⁺ fragments. Analyses based on canonical molecular orbitals, Mayer bond orders, and fragment-based correlation diagrams reveal the presence of a dative Fe→M interaction in FeM(CO)₉⁺, which formally enables the heavier Rh/Ir metal center to attain an 18-electron configuration. However, this bond is weaker than a typical covalent single bond, as the key molecular orbitals involved possess antibonding character. This study provides important insights into the structure and bonding of heteronuclear transition metal carbonyl clusters, highlighting distinctive coordination behavior between late 3d and heavier 4d/5d congeners. Full article

A novel heterobimetallic ruthenium(II)–gold(I) complex featuring a bridging bis(diphenylphosphino)butane (dppb) ligand was prepared and fully characterized. Single-crystal X-ray diffraction revealed a piano-stool geometry around Ru(II) with η⁶-cymene, two chlorido ligands, and one phosphorus atom from dppb, while the Au(I) center adopts a linear P–Au–Cl coordination. Structural integrity in the solution was confirmed by 1D and 2D NMR spectroscopy, while solution behavior was further monitored by variable solvent ³¹P NMR and UV/Vis spectroscopy, indicating that the organometallic Ru–arene core remains intact, whereas the chlorido ligands coordinated to Ru exhibit partial lability. Complementary characterization included elemental analysis, FTIR, and UV/Vis spectroscopy. Spectrofluorimetric and FRET analyses showed that Au(dppb), Ru(dppb), and the heterobimetallic AuRu complex bind to BSA with apparent constants of 1.41 × 10⁵, 5.12 × 10², and 2.66 × 10⁴ M⁻¹, respectively, following a static quenching mechanism. In vivo biological evaluation in Wistar rats revealed no significant hepatotoxicity or nephrotoxicity, with only mild and reversible histological alterations and preserved hepatocyte nuclear morphology. Hematological analysis indicated a statistically significant reduction in leukocyte populations, suggesting immunomodulatory potential, while elevated serum glucose levels point to possible endocrine or metabolic activity. These findings highlight compound structural stability and intriguing bioactivity profile, making it a promising platform for further organometallic drug development and testing. Full article

The synthesis and characterization of the tripodal phosphines RSi(CH₂CH₂PPh₂)₃ (R = Me, OMe, OEt) (1–3) is described. The ¹H NMR spectra of all phosphines display virtual coupling patterns. The ligands form the corresponding trinuclear Pd complexes [RSi(CH₂CH₂PPh₂)₃]₂(PdCl₂)₃ (4–6) with three PdCl₂ moieties sandwiched between two tripodal ligands. The complexes 4, 5, and 7 (R = OH) have been analyzed by single crystal X-ray diffraction. The coordination at the Pd center is square planar with the phosphine groups occupying trans positions. The ³¹P{¹H} MAS NMR spectra of polycrystalline 1 are in accordance with the packing motif of the molecules in the unit cell. The tripodal ligand 3 has successfully been immobilized on silica as 3i. It coordinates PdCl₂ on the surface, as demonstrated by ³¹P{¹H} MAS NMR. Hereby, the cis coordination is prevalent when 3i has maximal surface coverage. At low surface coverage, one tripodal linker can accommodate trans coordination at the metal center. A surface-bound trinuclear Pd complex has been generated, as well as a heterobimetallic Pd/Cu complex. All surface species have been characterized by ³¹P{¹H} MAS NMR. Full article

Heterobimetallic complexes of an ambidentate deferiprone derivative, 3-hydroxy-2-methyl-1-(3-((pyridin-2-ylmethyl)amino)propyl)pyridin-4(1H)-one (PyPropHpH), incorporating an octahedral [Co(4N)]³⁺ (4N = tris(2-aminoethyl)amine (tren) or tris(2-pyridylmethyl)amine (tpa)) and a half-sandwich type [(η⁶-p-cym)Ru]²⁺ (p-cym = p-cymene) entity have been synthesized and characterized by various analytical techniques. The reaction between PyPropHpH and [Co(4N)Cl]Cl₂ resulted in the exclusive (O,O) coordination of the ligand to Co(III) yielding [Co(tren)PyPropHp](PF₆)₂ (1) and [Co(tpa)PyPropHp](PF₆)₂ (2). This binding mode was further supported by the molecular structure of [Co(tpa)PyPropHp]₂(ClO₄)₃(OH)·6H₂O (5) and [Co(tren)PyPropHpH]Cl(PF₆)₂·2H₂O·C₂H₅OH (6), respectively, obtained via the slow evaporation of the appropriate reaction mixtures and analyzed using X-ray crystallography. Subsequent treatment of 1 or 2 with [Ru(η⁶-p-cym)Cl₂]₂ in a one-pot reaction afforded the corresponding heterobimetallic complexes, [Co(tren)PyPropHp(η⁶-p-cym)RuCl](PF₆)₃ (3) and [Co(tpa)PyPropHp(η⁶-p-cym)RuCl](PF₆)₃ (4), in which the piano-stool Ru core is coordinated by the (N,N) chelating set of the ligand. Cyclic voltammetric measurements revealed that the tpa complexes can be reduced at less negative potentials, suggesting their capability to be bioreductively activated under hypoxia (1% O₂). Hypoxia activation of 2 and 4 was demonstrated by cytotoxicity studies on the MCF-7 human breast cancer cell line. PyPropHpH was shown to be a typical iron-chelating anticancer agent, raising the mRNA levels of TfR1, Ndrg1 and p21. Further qRT-PCR studies provided unambiguous evidence for the bioreduction of 2 after 72 h incubation under hypoxia, in which the characteristic gene induction profile caused by the liberated iron-sequestering PyPropHpH was observed. Full article

The controlled formation of mixed-metal bimetallics was realised through use of a fac-[Re(CO)₃(N,N′-bpy-P)Cl] complex bearing an exogenous 2,4,6-trioxa-1,3,5,7-tetramethyl-8-phosphaadamantane donor at the 5-position of the bpy. The introduction of gold, silver, and rhodium with appropriate secondary ligands was readily achieved from established starting materials. Restricted rotation about the C_(bpy)-P bond was observed in several of the bimetallic complexes and correlated with the relative steric bulk of the second metal moiety. Related chemistry with the 6-substituted derivative proved more limited in scope with only the bimetallic Re/Au complex being isolated. Full article

We report a straightforward alkane elimination strategy to prepare well-defined heterobimetallic Al/Mo species. Notably, the reaction of the monohydride complex of molybdenum, Cp*MoH(CO)₃, with triisobutyl aluminum affords a new heterobimetallic [MoAl]₂ tetranuclear compound, [Cp*Mo(CO)(µ-CO)₂Al(ⁱBu)₂]₂, (1), featuring a 12-membered C₄O₄Mo₂Al₂ ring in which isocarbonyls bridge the Mo and Al centers. The addition of pyridine to this complex successfully results in the dissociation of the dimer into a new discrete binuclear complex, [Cp*Mo(CO)₂(µ-CO)Al(Py)(iBu)₂], (2). Switching the nature of the Lewis base from pyridine to tetrahydrofuran does not lead to the THF analogue of adduct 2, but rather to a complex reaction where one of the identified products corresponds to a tetranuclear species, [Cp*Mo(CO)₃(μ-CH₂CH₂CH₂CH₂O)Al(iBu)₂]₂, (3), featuring two bridging alkoxybutyl fragments originating from the C-O ring opening of THF. Compound 3 adds to the unusual occurrences of THF ring opening by heterobimetallic complexes, which is evocative of masked metal-only frustrated Lewis pair behavior and highlights the high reactivity of these Al/Mo assemblies. Full article

The paper describes a heterobimetallic mixed-ligand hexanuclear precursor [NaMn₂(thd)₄(OAc)]₂ (1) (thd = 2,2,6,6-tetramethyl-3,5-heptadionate; OAc = acetate) that was designed based on its lithium homoleptic analogue, [LiMn₂(thd)₅], by replacing one of the thd ligands with an acetate group in order to accommodate 5-coordinated sodium instead of tetrahedral lithium ion. The complex, which is highly volatile and soluble in a variety of common solvents, has been synthesized by both the solid-state and solution methods. The unique “dimer-of-trimers” heterometallic structure consists of two trinuclear [NaMn^II₂(thd)₄]⁺ units firmly bridged by two acetate ligands. X-ray diffraction techniques, DART mass spectrometry, ICP-OES analysis, and IR spectroscopy have been employed to confirm the structure and composition of the hexanuclear complex. Similar to the Li counterpart forming LiMn₂O₄ spinel material upon thermal decomposition, the title Na:Mn = 1:2 compound was utilized as the first single-source precursor for the low-temperature preparation of Na₄Mn₉O₁₈ tunnel oxide. Importantly, four Mn sites in the hexanuclear molecule can be potentially partially substituted by other transition metals, leading to heterotri- and tetrametallic precursors for the advanced quaternary and quinary Na-ion oxide cathode materials. Full article

A convenient synthesis of [HB(HImMe)₃](PF₆)₂ (ImMe = N-methylimidazolyl) is decribed. This salt serves in situ as a precursor to the tris(imidazolylidenyl)borate Li[HB(ImMe)₃] pro-ligand upon deprotonation with ⁿBuLi. Reaction with [W(≡CC₆H₄Me-4)(CO)₂(pic)₂(Br)] (pic = 4-picoline) affords the carbyne complex [W(≡CC₆H₄Me-4)(CO)₂{HB(ImMe)₃}]. Interrogation of experimental and computational data for this compound allow a ranking of familiar tripodal and facially coordinating ligands according to steric (percentage buried volume) and electronic (ν_CO) properties. The reaction of [W(≡CC₆H₄Me-4)(CO)₂{HB(ImMe)₃}] with [AuCl(SMe₂)] affords the heterobimetallic semi-bridging carbyne complex [WAu(μ-CC₆H₄Me-4)(CO)₂(Cl){HB(ImMe)₃}]. Full article

This review summarizes developments in the synthesis and catalytic applications of those heterobimetallic carbene complexes in which at least two different metals are bound to the same ligand by at least one M-C(carbene) bond each. Several new synthetic methods for such complexes yielding well-defined and thoroughly characterized compounds are presented. The new complexes were found to be catalytically active in several (most often tandem) reactions. In certain cases, the incorporation of two different metals into the same imidazole- or triazol-based NHC-carbene complex resulted in the substantially higher catalytic activity of the heterobimetallic complex compared either to its homobimetallic analogs or to mixtures of comparable mononuclear complex fragments containing the two metals independently. This is a clear demonstration of advantageous metal–metal cooperation within the catalyst. Opposite examples are also discussed, where the heterobimetallic carbene complex proved inferior in relation to its homobimetallic analogs or to mixtures of homonuclear fragments. Full article

Heterometallic phosphinidene complexes are appealing species for the construction of novel organophosphorus ligands thanks to the high reactivity expected from the combination of M-P multiple bonding and the intrinsically different electronic and coordination preferences of the distinct metals. In a preliminary study, we found that the heterobimetallic complex [MoReCp(μ-PMes*)(CO)₆] (Mes* = 2,4,6-C₆H₂^tBu₃) reacted with CN(p-C₆H₄OMe) via [2+1]-cycloaddition to form a novel azaphosphallene complex. We have now examined in detail the reactions of the above complex and those of its MoMn analogue with different isocyanides, which turned out to be strongly dependent on experimental conditions and on the size of the substituent at the isocyanide. All the products formed follow from one or several of the following reaction pathways: (i) CO substitution by CNR; (ii) addition of CNR at the group 7 metal centre; and (iii) [2+1] cycloaddition of isocyanide at a Mo=P bond to form azaphosphallene groups, with the former process being dominant in reactions at room temperature and for the Mn system. In contrast, low-temperature reactions of the Re system favoured the addition processes, with the [2+1] cycloaddition at Mo=P bonds only taking place at substrates without metal-metal bonds and when the size of the CNR group does not cause unbearable steric clashes when placed in between the Cp and Mes* groups. Full article

The reaction between the ((E)-N′-(2-hydroxy-3-methoxybenzylidene)pyrazine-2-carbohydrazide) (H₂opch) ligand and the metallo-precursor [Dy(hfac)₃]·2H₂O led to the formation of an homometallic coordination complex with the formula [Dy₂(hfac)₃(H₂O)(Hopch)₂][Dy(hfac)₄] (1). In presence of both [Dy(hfac)₃] 2H₂O and the Fe(II) salt, the heterobimetallic tetranuclear [FeDy₃(hfac)₈(H₂O)₂(opch)₂] (2) was isolated, while the addition of the co-ligand 1,2-Bis(2-hydroxy-3-methoxybenzylidene) hydrazine (H₂bmh) led to the formation of two heterobimetallic tetranuclear complexes with the formula [Fe₃Dy(hfac)₆(opch)₂(H₂bmh)] C₆H₁₄ (3) C₆H₁₄ and [Fe₂Dy₂(hfac)₇(opch)₂(H₂bmh)] 0.5C₇H₁₆ (4) 0.5C₇H₁₆. Single crystal X-ray diffraction and dc magnetic investigation demonstrated that 3 and 4 involved the iron center in the +II and +III oxidation states. Dynamic magnetic measurements highlighted the single-molecule magnet behavior of 1 and 2 in a zero applied dc field primarily due to the ferromagnetic interactions taking place in these compounds. Full article

An unusual heterobimetallic volatile compound [Pb₂Co₅(acac)₁₄] was synthesized by the gas phase/solid-state technique. The preparation can be readily scaled up using the solution approach. X-ray powder diffraction, ICP-OES analysis, and DART mass spectrometry were engaged to confirm the composition and purity of heterobimetallic complex. The composition is unique among the large family of lead(tin): transition metal = 2:1, 1:1, and 1:2 β-diketonates compounds that are mostly represented by coordination polymers. The molecular structure of the complex was elucidated by synchrotron single crystal X-ray diffraction to reveal the unique heptanuclear moiety {Co(acac)₂[Pb(acac)₂-Co(acac)₂-Co(acac)₂]₂} built upon bridging interactions of acetylacetonate oxygens to neighboring metal centers that bring their coordination numbers to six. The appearance of unique heptanuclear assembly can be attributed to the fact that the [Co(acac)₂] units feature both cis- and trans-bis-bridging modes, making the polynuclear moiety rather flexible. This type of octahedral coordination is relatively unique among known lead(tin)-3d transition metal β-diketonates. Due to the high-volatility, [Pb₂Co₅(acac)₁₄] can be potentially applied as a MOCVD precursor for the low-temperature preparation of lead-containing functional materials. Full article