Open research questions in Organometallic Complex Synthesis and Catalysis
40 unresolved questions extracted from the limitations and future-work sections of 102 Organometallic Complex Synthesis and Catalysis papers in our library. Each links back to the study that raised it.
What the literature leaves open
The homogeneous conversion of ambient dinitrogen to amine products via the N 2 reduction reaction (N 2 RR) remains a prized yet challenging feat for d-block complexes and is scarcely reported for f-block complexes.
Catalytic Ambient Temperature Dinitrogen Conversion to a Bis(silyl)amine by Mononuclear Group 4 Aryloxide Complexes · 2026 · DOIThe catalytic activity of cyclooctatetraenyl dianion complexes with alkali, alkaline earth, transition, lanthanide, and actinide metals has not been investigated, despite the potential for these multi-metal coordination platforms to enable novel catalytic transformations.
The unique coordination modes available in transition metal-COT2- complexes have not been systematically exploited or evaluated for their chemical and physical properties, limiting the rational design of new functional materials from these ligand-metal combinations.
Heterobimetallic lanthanide-transition metal multi-decker sandwich complexes with COT2- ligands have not been prepared or characterized, representing an unexplored synthetic target in organometallic f-element chemistry.
The synthesis and characterization of triple- and tetra-decker sandwich complexes with cyclooctatetraenyl dianion (COT2-) ligands coordinated to alkali, alkaline earth, and transition metals has not been systematically explored, leaving the accessibility and structural properties of these multi-decker architectures unknown.
For Ni-catalyzed C-N cross-coupling, CF3-substituted dppf-analogs (14 and 15) show little effect compared to unsubstituted dppf despite similar 31P NMR shifts; direct measurement of Ni-phosphine binding affinities and electronic properties of these ligands through complementary spectroscopic methods (e.g., FTIR, UV-vis) is needed to explain the lack of electronic differentiation.
The Pd-catalyzed oxidative carbonylation reaction shows that o-OMe substituted dppf (6) and unsubstituted dppf outperform o-CF3 (14) and all-tBu (18) analogs, but mechanistic investigation of how ortho-substituents on ferrocenyl rings affect carbonyl insertion kinetics versus reductive elimination selectivity is not provided.
The CO2-insertion energy barriers for compounds 4 and 28 were calculated using multiple computational methods (ωB97X-D, B3LYP-D3, M06-2X-D3); experimental kinetic validation of these calculated energy barriers through direct measurement of CO2-insertion rates with sterically demanding dppf-analogs has not been performed.
Asymmetric catalysis with chiral dppf-analogs shows inconsistent structure-activity relationships across different transformations (Rh-catalyzed hydrogenation, Pd-catalyzed allylic substitution, Ru-catalyzed hydrogenation); systematic comparison of chiral dppf-analogs across identical reaction classes with controlled steric and electronic parameters is lacking.
The trans-influence study on reductive elimination rates using dissymmetric ligands 30 and 31 shows ambiguous trends for the series XR=CF3, YR=CF3, and ZR=CF3 where the ligand trans to amido is varied; systematic investigation of additional electron-withdrawing and electron-donating substituents on dissymmetric dppf-analogs is needed to clarify the competing electronic effects on reductive elimination kinetics.
The p-cymene derivative targeting plectin showed anticancer activity in a murine colon carcinoma tumor model, but in vivo efficacy data are limited to a single mouse model. Additional pharmacokinetic studies, biodistribution analysis, and evaluation in alternative cancer models (primary tumors, invasive melanomas) are needed to establish the therapeutic potential of arene ruthenium complexes as anticancer agents.
The selectivity challenge for arene ruthenium–protein interactions remains unresolved: while thiomaltol-based complexes target Topo II and pyridinecarbothioamide complexes target plectin, no systematic methodology exists to predict or design arene ruthenium complexes with high selectivity for specific proteins while avoiding off-target interactions with the proteome.
Only one example of metallomesogen containing arene ruthenium complexes has been reported (the three-component system with pyrenyl-functionalized poly(arylester) dendrimers). The facility to modify and interchange different components suggests systematic exploration of alternative dendrimer structures, varied anion types, and different arene ligands is needed to establish design principles for arene ruthenium liquid-crystalline materials.
Lawrencium's chemical behaviour resembles actinide trivalent ions despite its unique atomic ground state (7s27p1/21 versus lutetium's 6s26d1), but this conclusion relies on computed reaction energies for only three simple molecular systems (MH3 decomposition); comprehensive experimental or computational characterization of lawrencium coordination chemistry with hard f-element ligands is lacking.
The stabilization of BkIV using 3,4,3-LI(1,2-HOPO) siderophore analogue successfully lowered the Bk4+/Bk3+ redox potential from +1.60 V to −0.1 V NHE, but B3LYP DFT calculations have not been validated experimentally for other transplutonium tetravalent complexes (e.g., CfIV or EsIV analogues) to confirm whether this chelation strategy generalizes beyond berkelium.
DFT calculations of the Bk(HDPA)3 complex show negligible differences in metal–ligand bonding when 5f orbitals are treated as valence versus effective core potential, but this finding has not been systematically tested across the full 5f series (Am through Cf) to determine at which point the core treatment becomes valid.
Berkelium ligand field splittings are reported to be an order of magnitude smaller than californium's, but this comparison is based on limited structural analogues (borate and HDPA complexes); systematic computational screening using hybrid DFT of Bk complexes with varying ligand donor strength and geometry is needed to establish whether this trend generalizes.
The prediction that transuranic elements beyond californium will display even greater deviations from lanthanide behaviour lacks computational or experimental validation beyond berkelium; CASSCF-SO calculations of einsteinium, fermium, or mendelevium complexes with borate or dipicolinic acid ligands are needed to test this periodicity break hypothesis.
The enhanced ligand field effects observed in californium complexes are hypothesized to arise from the accessibility of CfII, but computational validation of this redox mechanism using CASSCF or DFT calculations has not been performed for the An(HDPA)3·H2O series (An = Am–Cf) to confirm whether CfII formation actually occurs under the conditions studied.
Protonation of carbyne complex 217 with phenols (Ar = 2,6-C6H3Cl2, 2,6-C6H3Me2, 2,6-C6H3(iPr)2, 2,6-C6H3(OMe)2) and of [Re(≡CMe3)(NH-2,6-C6H3Me2)Cl3]2 (214) with potassium phenoxides yields carbene products through formal protonation of the carbyne carbon, but the electronic and steric effects of phenol/phenoxide substituents on protonation efficiency and regioselectivity remain quantitatively unexamined.
Deprotonation of aminocarbyne complex [ReCl(CNHMe)(CNMe)2(PMePh2)2]SbF6 (89b) with THF produces isocyanide product 90b, and reaction with zinc in acetonitrile gives 321, but the mechanistic differences between solvent-mediated deprotonation and metal-mediated reductive deprotonation of aminocarbynes have not been characterized.
The unexpected formation of carbyne complex 343 alongside expected carbene complex 344 in the reaction of [Cp(CO)2Re≡CPh]BBr4 (311) with 1-lithio-o-carborane (Scheme 68) indicates a competing rearrangement pathway, but the factors controlling carbyne versus carbene product selectivity in carborane-metal interactions remain unexplored.
Nucleophilic addition reactions to [Cp(CO)2Re≡CPh]BCl4 (2) with diverse nucleophiles (LiMe, BuLi, fluoride, chloride, cyanide, thiocyanate, LiPbPh3, selenolate, PMe3) yield carbene products, but the regioselectivity, reaction rates, and mechanistic pathways for competing nucleophile attack versus ligand substitution have not been quantitatively compared.
The [3+2] cycloaddition reactions of rhenium carbene-carbyne complexes with ethylene (Scheme 61) proceed through intermediates 315 that can be observed spectroscopically in some cases, but the effect of different alkoxy (R = CMe3, CMe2CF3, OCMe(CF3)2) and thiophenoxy substituents on reaction pathway selectivity and intermediate stability has not been systematically investigated.
The cycloaddition reactions of rhenium carbyne complexes with N-oxides (Schemes 58-60) show formation of observed intermediates 315 in some cases, but spectroscopic characterization and kinetic analysis of these intermediates across different carbyne ligand substituents (R = H, alkyl, aryl) remain incomplete.
Most-cited papers in Organometallic Complex Synthesis and Catalysis
- The chemistry of univalent metal β-diketiminates · Coordination Chemistry Reviews · 2012 · 249 citations
- Regioselective hydroformylation of propene catalysed by rhodium-zeolite · Nature · 2024 · 123 citations
- Transuranic Computational Chemistry · Chemistry – A European Journal · 2018 · 62 citations
- Aminocarbyne ligands in organometallic chemistry · Coordination Chemistry Reviews · 2021 · 56 citations
- Chemistry of sterically demanding dppf-analogs · Coordination Chemistry Reviews · 2021 · 46 citations
- Coordination chemistry of poly(thioether)borate ligands · Coordination Chemistry Reviews · 2010 · 37 citations
- Chemistry of rhenium carbyne complexes · Coordination Chemistry Reviews · 2013 · 36 citations
- Recent developments in two coordinate transition metal chemistry · Coordination Chemistry Reviews · 2023 · 21 citations
- Organoruthenium-bipyridyl complexes – A platform for diverse chemistry and applications · Coordination Chemistry Reviews · 2024 · 20 citations
- Arene Ruthenium Complexes in Supramolecular Chemistry · Advances in Inorganic Chemistry · 2018 · 10 citations
Most recent work
- Palladium-Catalyzed Markovnikov Hydroformylation of Olefins · Journal of the American Chemical Society · 2026
- Hydroformylation of Alkenylbenzenes Catalyzed by Rhodium-Phosphine Complexes: Mechanistic Features and Kinetic Behavior Resolved Through Bayesian Analysis · Catalysts · 2026
- A silver rush in organic chemistry · Science · 2026
- Multifaceted Lewis Acidity of a High‐Valent Cu(III) Hydroxide Complex · ChemistryEurope · 2026
- Speciation of Bulky Chiral Cyclopentadienyl Cobalt(III) Complexes: Isolation of Air-Stable 16-Electron Species · ChemRxiv · 2026
- Diiron(I) Bis(cyclopentadienyl) Complexes with Bridging Iminium Ligands: From Foundational Organometallic Chemistry to Unique Reactivity and Biological Potential · Accounts of Chemical Research · 2026
- Stereochemical Modulation of Palladacyclopentadienyl Complexes Bearing Diphosphine Ligands: A Key to Enhanced DNA Interaction and Anticancer Activity · European Journal of Inorganic Chemistry · 2026
- Development of Quinoline-Amido and Hydrogenated Quinoline-Imino Hafnium Complexes and Their Olefin Polymerizations · Inorganic Chemistry · 2026
- Iron Complexes Supported by a Dual Dearomatized PNPN Ligand · Inorganic Chemistry · 2026
- A Novel Heterometallic Ring {Cr <sub>5</sub> Ni <sub>3</sub> } and New {Cr <sub>6</sub> Co <sub>2</sub> } and {Cr <sub>6</sub> Zn <sub>2</sub> } Rings · Chemistry – A European Journal · 2026
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