SPANphos is an

organophosphorus compound Organophosphorus chemistry is the scientific study of the synthesis and properties of organophosphorus compounds, which are organic compounds containing phosphorus. They are used primarily in pest control as an alternative to chlorinated hydrocarbo ...

used as a ligand in

organometallic Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkali, alkaline earth, and transition metals, and so ...

and

coordination chemistry A coordination complex is a chemical compound consisting of a central atom or ion, which is usually metallic and is called the ''coordination centre'', and a surrounding array of chemical bond, bound molecules or ions, that are in turn known as ' ...

. The compound is a rare example of a

trans-spanning ligand Trans-spanning ligands are bidentate ligands that can span opposite sites of a complex with square-planar geometry. A wide variety of ligands that chelate in the cis fashion already exist, but very few can link opposite vertices on a coordination po ...

and rigidly links mutually trans coordination sites. By virtue of its C₂-symmetric backbone, SPANphos forms a chiral cavity over the face of a square planar complexes, e.g. in MCl₂(SPANphos) (M = Pd, Pt). WABXIH

Synthesis

SPANphos can be prepared synthesized from relatively inexpensive reagents. In the first step 4,4,4',4',6,6'-hexamethyl-2,2'-spirobi

chromane Chromane (benzodihydropyran) is a heterocyclic chemical compound with the chemical formula C9H10O. Chromane is a structural feature of more complex compounds including E vitamins (tocopherols and tocotrienols), Dianin's compound, and the pharma ...

is prepared via an acid-catalyzed reaction of

p-cresol ''para''-Cresol, also 4-methylphenol, is an organic compound with the formula CH3C6H4(OH). It is a colourless solid that is widely used intermediate in the production of other chemicals. It is a derivative of phenol and is an isomer of ''o''- ...

and

acetone Acetone (2-propanone or dimethyl ketone) is an organic compound with the chemical formula, formula . It is the simplest and smallest ketone (). It is a colorless, highly Volatile organic compound, volatile, and flammable liquid with a charact ...

. The resultant spirocycle is halogenated with

N-bromosuccinimide ''N''-Bromosuccinimide or NBS is a chemical reagent used in radical substitution, electrophilic addition, and electrophilic substitution chemical reaction, reactions in organic chemistry. NBS can be a convenient source of Br•, the bromine radi ...

followed by lithium-bromide exchange using n-BuLi. Treatment of the resulting dilithio compound with

chlorodiphenylphosphine Chlorodiphenylphosphine is an organophosphorus compound with the formula (C6H5)2PCl, abbreviated Ph2PCl. It is a colourless oily liquid with a pungent odor that is often described as being garlic-like and detectable even in the ppb range. It is ...

completes the synthesis.{{cite journal , author = Z. Freixa, M. S. Beentjes, G. D. Batema, C. B. Dieleman, G. P. F. van Strijdonck, J. N. H. Reek, P. C. J. Kamer, J. Fraanje, K. Goubitz and P. W. N. M. van Leeuwen , title = SPANphos: A ''C''₂-Symmetric ''trans''-Coordinating Diphosphane Ligand , journal = Angewandte Chemie International Edition , year = 2003 , volume = 42 , issue = 11 , pages = 1322–1325 , doi = 10.1002/anie.200390330 , pmid = 12645065 : SPANphosPrep

References

Diphosphines