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Urea‐bridged Bicyclic Bisphosphines Containing the Grouping P‐CCl 2 ‐P
Author(s) -
Shevchenko Igor,
Fischer Axel K.,
Jones Peter G.,
Schmutzler Reinhard
Publication year - 2002
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/1521-3749(200208)628:8<1903::aid-zaac1903>3.0.co;2-q
Subject(s) - chemistry , dimer , stereochemistry , crystallography , ring (chemistry) , crystal structure , urea , bicyclic molecule , molecule , nmr spectra database , spectral line , organic chemistry , physics , astronomy
Some chemical properties of the cyclic bisphosphines 3b and 6 , which contain the grouping P‐CCl 2 ‐P, are discussed. Reduction of 3b with R 3 P (R = i‐Pr, Ph) gives the dimer 11 of the phosphaalkene 10 . 11 may have different structures in solution and in crystalline form. The bridging of 6 with the silylated urea 2 gives the unsymmetrical product 7 , which rearranges slowly into 8 . Compounds 7 and 8 exhibit unprecedentedly low chemical shifts in the 31 P NMR. The structures of 8 and 11 were established by X‐ray analysis and their NMR spectra are discussed. The four‐membered ring of 8 is non‐planar, with a fold angle of 32° about the C···C axis. Two non‐crystallographic mirror planes pass through (i) the two CCl 2 groups and the CO group and (ii) the two phosphorus atoms and the urea unit. The structure of 11 consists of two independent molecules, each with crystallographic inversion symmetry; each four‐membered ring has one long and one short P‐C bond.