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lutetium(III) Chloride

LuCl3 salt
Molar Mass
281.320 g/mol
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Properties

StateSolid (hygroscopic; commonly hydrated)
Colorwhite
SolubilityVery soluble in water; soluble in alcohols
Melting Point800 °C (anhydrous)

About lutetium(III) Chloride

Lutetium(III) chloride is a white hygroscopic salt that you can buy as the anhydrous powder or — more commonly — as the heptahydrate or hexahydrate, because the anhydrous form is genuinely difficult to make from aqueous solution. Heat the hydrate in air and you don't get LuCl3, you get the oxychloride LuOCl with HCl evolved, a frustration shared by most heavy-lanthanide trichlorides. Clean anhydrous LuCl3 requires either vacuum sublimation, NH4Cl-assisted dehydration under flowing argon, or direct synthesis from Lu metal and Cl2 at red heat. In the crystal, Lu(III) sits in a 9-coordinate tricapped trigonal prism, the typical coordination geometry for the larger Ln(III) ions. The compound matters because it is the soluble entry point to all of lutetium's specialty applications: LSO scintillator synthesis (via reaction with SiO2 in the melt), Lu metal production by Ca reduction or molten-salt electrolysis, and especially Lu-177 radiopharmaceutical chemistry. Lu-177 is produced by neutron irradiation of Lu-176 (2.6% natural abundance) in research reactors at HFIR (Oak Ridge) or NRG Petten, has a 6.65-day half-life, and emits beta particles with a 2 mm tissue range that is essentially perfect for targeted internal radiotherapy. The DOTA chelator built into Lutathera (Lu-177 DOTATATE, FDA 2018, neuroendocrine tumors) and Pluvicto (Lu-177 PSMA-617, FDA 2022, metastatic castration-resistant prostate cancer) is loaded from no-carrier-added Lu-177 chloride solutions — making LuCl3 the proximate starting material for what is now a $5B+ theranostic market.

Where you'll encounter it

If you've ever read a press release about Pluvicto or Lutathera shrinking metastatic prostate or neuroendocrine tumors with Lu-177 beta therapy, the radioisotope arrived at the radiopharmacy as a no-carrier-added LuCl3 solution before being loaded onto its DOTA-targeting peptide. Novartis ships Pluvicto vials to over 200 US theranostic centers per week — each dose started as a tiny aliquot of Lu-177 LuCl3 produced at Oak Ridge HFIR or NRG Petten, conjugated under radiopharmacy hot-cell conditions with PSMA-617 peptide, and infused into a metastatic castration-resistant prostate cancer patient within days of production (the 6.65-day half-life is unforgiving). PET scanner manufacturers also pull stable LuCl3 into the synthesis of Lu2SiO5 (LSO) scintillator boules. Radiochemistry labs studying lanthanide separations use it as the standard heavy-end Ln(III) reference in their HDEHP solvent extraction screens.

Common Uses

  • Starting material for Lu-177 DOTATATE (Lutathera) and Lu-177 PSMA-617 (Pluvicto) radiopharmaceutical synthesis
  • Precursor for Lu2SiO5 (LSO) scintillator-crystal growth used in PET detectors
  • Lewis-acid catalyst for ring-opening polymerizations and aldol-type reactions
  • Dopant source for laser-crystal and phosphor synthesis (Yb:Lu2O3, Lu3Al5O12)
  • Feedstock for Lu metal production via molten-salt electrolysis
  • Reference standard in ICP-MS lanthanide quantification
  • Substrate for Lu-based MOF and coordination-polymer research
  • Analytical reagent in lanthanide-separation method development

Safety Information

GHS: Skin Irrit. 2 (H315), Eye Irrit. 2A (H319), STOT SE 3 (H335). Moderate acute toxicity (no specific OSHA PEL; lanthanide trichlorides handled under nuisance-dust controls, ACGIH TLV 10 mg/m3 inhalable for soluble Ln compounds is a typical workplace target). Hydrolyzes on contact with moisture to release HCl — handle anhydrous material in glovebox or under inert atmosphere. The Lu-177-loaded form (no-carrier-added LuCl3 in dilute HCl) is a beta-gamma emitter requiring NRC-licensed handling, lead shielding, and dose monitoring per 10 CFR 20.

This safety summary is for educational reference only and may not be complete. It is not a substitute for Safety Data Sheets (SDS), medical advice, or professional chemical safety guidance. Always consult appropriate SDS and qualified professionals before handling chemicals.

Constituent Elements

Lu — Lutetium Cl — Chlorine

Frequently Asked Questions

What is the molar mass of lutetium(III) chloride?
Anhydrous LuCl3 is 281.32 g/mol — Lu (174.97) + 3 Cl (3 x 35.45 = 106.35). Common hydrates: heptahydrate LuCl3.7H2O is 407.43 g/mol, hexahydrate LuCl3.6H2O is 389.42 g/mol. For radiopharmacy, the chemical mass is essentially negligible — Lu-177 is delivered no-carrier-added at activities of 10-200 GBq from a few microliters of dilute HCl solution containing nanogram-to-microgram total Lu.
What are Lu-177 radiopharmaceuticals?
Lu-177 is a 6.65-day-half-life beta emitter produced by neutron activation of Lu-176 in research reactors. Its beta particles average 150 keV and travel about 2 mm in tissue — long enough to kill clusters of tumor cells but short enough to spare distant healthy tissue. The targeting molecule (DOTATATE for somatostatin receptors on neuroendocrine tumors, PSMA-617 for prostate-specific membrane antigen) carries a DOTA chelator that loads Lu-177 from LuCl3 solution, then circulates and binds the tumor for hours. The accompanying low-energy gammas (113 keV, 208 keV) let the same dose be SPECT-imaged. Lutathera (FDA 2018) and Pluvicto (FDA 2022) define the modern theranostic playbook.
Why is anhydrous LuCl3 hard to prepare?
Heating LuCl3.7H2O in air drives off water but also drives off HCl, leaving the oxychloride LuOCl behind. The same hydrolysis defeats most heavy-lanthanide trichloride dehydrations because the Ln-O bond is competitive with Ln-Cl on energetic grounds. Three workarounds are standard: vacuum sublimation of crude LuCl3 at around 800 °C, dehydration of the hydrate while mixed with an excess of NH4Cl under flowing argon (the NH4Cl decomposition keeps the gas phase HCl-rich and suppresses oxychloride formation), or direct synthesis from Lu metal turnings under flowing Cl2 gas at red heat.