What are the hazards of nickel carbonyl?

Nickel tetracarbonyl, also known as carbonyl nickel or tetracarbonylnickel, is an organometallic complex with the molecular formula Ni(CO)4. First synthesized in 1890 by Ludwig Mond, it was the first synthetic simple metal carbonyl complex. At room temperature, nickel tetracarbonyl is a colorless liquid that is highly volatile and extremely toxic. Table of Contents 1 Structure 2 Preparation 3 Reactions 4 Toxicity 5 External Links 6 References The structure of Ni(CO)4 is tetrahedral, with the Ni atom at the center connected to four carbonyl groups (carbon monoxide ligands). In the CO ligand, the C-O bond is a triple bond, with the carbon end coordinating to the metal. It took some time to determine the structure of tetracarbonylnickel, to the point that most publications before 1950 believed it to be composed of CO chains chelated to the metal. Like other metal carbonyl complexes such as pentacarbonyl iron and hexacarbonyl molybdenum, nickel tetracarbonyl has 18 valence electrons, satisfying the 18-electron rule. All of these complexes have a symmetrical structure, are charge-free, and are highly volatile. The formal oxidation state of the nickel atom in tetracarbonylnickel is zero. In 1890, Ludwig Mond first synthesized Ni(CO)4 by reacting nickel with carbon monoxide. This was the first simple metal carbonyl compound to be synthesized, sparking a surge in the synthesis and study of carbonyl complexes, among which V, Cr, Mn, Fe, and Co are important. Metallic nickel can react with carbon monoxide at room temperature to form tetracarbonylnickel. The process of purifying metallic nickel using the Mond method involves passing carbon monoxide over the surface of impure nickel at 323 K, resulting in the formation of tetracarbonylnickel; subsequent heating then causes tetracarbonylnickel to decompose into metallic nickel, thereby achieving purification. Similar to other low-cost metal carbonyl complexes, Ni(CO)4 can undergo substitution reactions and oxidation reactions. Reaction with Lewis basic ligands such as triphenylphosphine yields Ni(CO)3(PPh3) and Ni(CO)2(PPh3)2, in a manner similar to the reaction with 2,2’-bipyridine. Chlorine and other halogens can oxidize tetracarbonylnickel to NiCl2 while releasing CO gas, which can be used to destroy excess tetracarbonylnickel. Reduction of tetracarbonylnickel or treatment with hydroxides yields the cluster compounds 2− and 2−. Ni(CO)4 can carbonylate halides or halogenated aromatics; for example, vinyl bromides such as PhCH=CHBr react with tetra-cobaltocene and sodium methoxide to yield unsaturated esters. Such reactions may proceed via a Ni(CO)3 intermediate, followed by an oxidative addition reaction. Metal carbonyl complexes are susceptible to attack by nucleophiles; treating Ni(CO)4 with a nucleophile (Nu−) yields an acyl derivative. Toxic Ni(CO)4 is highly volatile and extremely toxic, due to the combined effect of the nickel powder released upon decomposition and carbon monoxide in the body. Skin contact, especially inhalation of tetracarbonylnickel, can be fatal; the LC50 after 30 minutes of exposure is approximately 3 ppm, while the concentration that causes immediate death is 30 ppm. Its vapor has a smell of rot and soot, and it can catch fire on its own in the air. Laboratories that use nickel tetracarbonyl often keep canaries, which are more sensitive to it, to indicate the concentration of nickel tetracarbonyl. Nickel poisoning can be divided into two stages. Symptoms during the first phase include headache and chest pain, which can last for several hours before subsiding. The second phase occurs 16 hours later, characterized by coughing, difficulty breathing, and severe fatigue caused by pneumonia; the symptoms reach their most severe level after four days, and death may occur due to cardiopulmonary and acute renal failure. Recovery takes a long time, and it is often accompanied by symptoms such as fatigue, depression, and difficulty breathing. Cases of permanent respiratory damage caused by nickel tetracarbonyl are not common, and its carcinogenicity remains controversial. External links: International Chemical Safety Card 0064 – Information page on tetracarbonylnickel; NIOSH Chemical Safety; European Chemicals Agency; IARC on “Nickel and its compounds”; NIST database. References: ^ Mond L, Langer K, Quincke F. Action of carbon monoxide on nickel. Journal of the Chemical Society. 1890: 749-753. DOI; Lascelles, Keith; Morgan, Lindsay G.; & Nicholls, David. Nickel Compounds. Ullmann’s Encyclopedia of Industrial Chemistry. 1991, A17 (5): 235-249. EROS Encyclopedia of Reagents for Organic Synthesis, John Wiley & Sons, 2003. C. Elschenbroich, A. Salzer, “Organometallics: A Concise Introduction” (2nd Ed), Wiley-VCH: Weinheim, 1992. ISBN 3-527-28165-7; Shi Z. Nickel carbonyl: toxicity and human health. The Science of the Total Environment. 1991, 148: 293-298. DOI; Sunderman FW. A Pilgrimage into the Archive of Nickel Toxicology. Annals of Clinical and Laboratory Science. 1989, 19: 1-16; Armit HW. The toxicity of nickel carbonyl. Part II. Journal of Hygiene. 1908, 8: 565-610; Armit HW. The toxicity of nickel carbonyl. Journal of Hygiene. 1907, 7: 525-551; Barceloux DG. Nickel. Journal of Toxicology–Clinical Toxicology. 1999, 37: 239-258. DOI.