SPANphos

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SPANphos is an organophosphorus compound used as a ligand in organometallic and coordination chemistry. The compound is a rare example of a trans-spanning ligand 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).

SPANphos
Names
Preferred IUPAC name
(4,4,4′,4′,6,6′-Hexamethyl-3,3′,4,4′-tetrahydro-2,2′-spirobi[[1]benzopyran]-8,8′-diyl)bis(diphenylphosphane)
Identifiers
3D model (JSmol)
  • InChI=1S/C47H46O2P2/c1-33-27-39-43(41(29-33)50(35-19-11-7-12-20-35)36-21-13-8-14-22-36)48-47(31-45(39,3)4)32-46(5,6)40-28-34(2)30-42(44(40)49-47)51(37-23-15-9-16-24-37)38-25-17-10-18-26-38/h7-30H,31-32H2,1-6H3
    Key: RQMTZMWXNZQOPD-UHFFFAOYSA-N
  • CC1=CC(=C2C(=C1)C(CC3(O2)CC(C4=CC(=CC(=C4O3)P(C5=CC=CC=C5)C6=CC=CC=C6)C)(C)C)(C)C)P(C7=CC=CC=C7)C8=CC=CC=C8
Properties
C47H46O2P2
Molar mass 704.814 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Structure of PtCl2(SPANphos)[1]

Synthesis

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SPANphos can be prepared synthesized from relatively inexpensive reagents. In the first step 4,4,4',4',6,6'-hexamethyl-2,2'-spirobichromane is prepared via an acid-catalyzed reaction of p-cresol and acetone. The resultant spirocycle is halogenated with N-bromosuccinimide followed by lithium-bromide exchange using n-BuLi. Treatment of the resulting dilithio compound with chlorodiphenylphosphine completes the synthesis.[1]

 
Preparation of SPANphos from p-cresol

References

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  1. ^ a b 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 (2003). "SPANphos: A C2-Symmetric trans-Coordinating Diphosphane Ligand". Angewandte Chemie International Edition. 42 (11): 1322–1325. doi:10.1002/anie.200390330. PMID 12645065.{{cite journal}}: CS1 maint: multiple names: authors list (link)