trans,trans,trans-(1,5,9-Cyclododecatriene)nickel(0) a organonickel compound with the formula NiC12H18, better known as t-Ni(cdt). It is a 16-electron coordination complex featuring trigonal planar nickel(0) bound to the three alkene groups in the cyclododecatrieneligand.[1] X-ray structural analysis demonstrates that the three olefins adopt a propeller-like arrangement around the nickel atom center, making the structure chiral.[2] This extremely air-sensitive deep red solid was the first discovered Ni(0)-olefin complex.[3]
Preparation and properties
The complex is prepared by reduction of anhydrous nickel(II) acetylacetonate in ether in the presence of the triolefin:[4]
σ-Donating ligands such as carbon monoxide, isonitriles, phosphines, and hydrides can readily add onto t-Ni(cdt) to furnish tetrahedral 18-electron nickel complexes.[5] It has been demonstrated that this fourth coordination site can be leveraged to separate the t-Ni(cdt) enantiomers with recrystallization of diastereomeric 18-electron t-Ni(cdt)L* complexes (where L* = optically active dimethylmenthylphosphine ligand).[3][4]
Applications
The all-trans-(cdt) ligand has been shown to be easily displaced with olefins such as trans-cyclooctene,[3]ethylene,[6] all-cis-(cdt),[7]norbornene,[6][8] to give the corresponding colorless 16-electron Ni(0)-olefin complexes with coplanar geometry. Ni(cod)2 can also be easily prepared from Ni(cdt).
Formation of other 16-electron Ni(0)-olefin complexes from t-Ni(cdt)
Recently, it was demonstrated that t-Ni(cdt) can be used to synthesize unique air-stable 16-electron Ni(0)–olefin complexes, such as Ni(Fstb)3 and Ni(4-tBustb)3 using (E)-stilbene ligands.[9][10]
References
↑Wilke, G. (1960). "Hauptversammlung der Gesellschaft Deutscher Chemiker". Angewandte Chemie72 (16): 581–582. doi:10.1002/ange.19600721611.
↑Brauer, D. J.; Krüger, C. (1972). "The three-dimensional structure of trans.trans,trans-1,5,9-cyclododecatrienenickel". Journal of Organometallic Chemistry44 (2): 397–402. doi:10.1016/S0022-328X(00)82929-0.
↑Bogdanović, B.; Kröner, M.; Wilke, G. (1966). "Übergangsmetallkomplexe, I. Olefin-Komplexe des Nickels(0)". Justus Liebigs Annalen der Chemie699 (1): 1–23. doi:10.1002/jlac.19666990102. PMID5986842.