104489-92-1Relevant articles and documents
Coordination chemistry of the bicycloaminophosphorane Ph(H)P[(OCH2CH2)2N], a potential P/N ligand. Access to iron and ruthenium phosphoranides. Reversible migration of a phenyl group between iron and phosphorus: Crystal and molecular structure of η5-CpFe(CO)[P(OCH2CH2) 2N](η1-C6H5)
Vierling, Pierre,Riess, Jean G.,Grand, André
, p. 4144 - 4152 (2008/10/08)
The bicyclic aminophosphorane 1, in its open tautomeric form 1′, behaves toward η5-CpFe(CO)2X (X = Cl, Br) mainly as a P-bonded monodentate ligand by displacement of X, and as a P/N bidentate ligand by replacement of CO and X, to yield the cationic derivatives 8a,b,d and 10a,b,d, respectively. With η5-CpRu(CO)2Cl, only the latter behavior is observed, leading to the cationic complex 10c. In solution, the P/N chelates 10 are in equilibrium with the isomeric neutral derivatives 9, as a result of competition between N and X for coordination to the metal. Abstraction of the N-borne proton by LiMe in the cationic chelates 11 leads quantitatively to the first iron and ruthenium phosphoranide adducts 13. In the case of ruthenium, prior formation of the amido-phosphane chelate 12c is observed. The iron species 13b,d convert, under heating, into the iron η1-phenyl derivatives 15b,d as a result of migration of the phenyl group from phosphorus to iron, with concomitant conversion of the phosphoranide ligand into a phosphane ligand. Adduct 15b, C16H18FeNO3P, crystallizes in the monoclinic space group P21/n, with a = 7.776 (1) A?, b = 14.477 (3) A?, c = 14.083 (1) A?, β= 102.04 (1)°, and Z = 4. The Fe-C(Ph) (2.037 (5) A?), Fe-C(CO) (1.715 (5) A?), and Fe-P (2.105 (3) A?) bond lengths are among the shortest distances known for complexes of this type. The P-N bond is also remarkably short (1.692 (4) A?) in spite of the fact that the nitrogen atom is markedly pyramidal (∑N = 333 ± 9.0°). The phenyl group migration is quantitatively reversed from iron back to phosphorus under the action of gaseous HCl. Chemical labeling of the phenyl ring excludes an ortho-metalation pathway and shows that it is the same carbon atom that is bonded alternately to phosphorus and to iron, establishing a 1,2-sigmatropic shift mechanism for this reversible phenyl migration. Furthermore, this phenomenon exemplifies (i) a metal-induced interconversion between a hypervalent P(V) phosphorane (1) and a trivalent P(III) phosphane derivative (17) and (ii) the possible intermediate formation of phosphoranide adducts in P-C bond rupture processes.
