Structural characterization of the triply bonded dirhenium(II) complexes Re2Cl4(.mu.-Ph2PCH2PPh2)2 and .alpha.-Re2Cl4(Me2P(CH2)2PMe2)
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The complexes Re2Cl4(LL)2, where LL are the bidentate ligands Ph2PCH2PPh2 (dppm) (1) and Me2P(CH2)2PMe2 (dmpe) (2), which both possess the electronic configuration σ2π4δ2δ∗2 and thus formally a metal-metal triple bond, have been structurally characterized by X-ray crystallography. Re2Cl4(dppm)2 (1): Re2P4C50H44; monoclinic, P21/n; a = 11.647 (3) Å, b = 12.849 (4) Å, c = 38.691 (9) Å, β = 85.96 (2)°, V= 5776 (43) Å3, Z = 4. The molecule has two dppm molecules spanning the Re-Re bond. The two fused five-membered rings assume twist-boat conformations, leading to a completely staggered arrangement of the substituents on the two rhenium atoms. The average Cl-Re-Re-Cl torsion angle is 56 °, and the Re-Re bond length is 2.234 (3) Å. Re2Cl4(dmpe)2.CH3OH (2) was isolated and crystallized as the α isomer, viz., with the dmpe ligands chelating. The crystallographic parameters are as follows: Re2Cl4P4OC13H36; orthorhombic, Ccma (nonstandard setting of Cmca); a = 11.595 (2) Å, b = 14.475 (2) Å, c = 14.925 (2) Å, V= 2505 (1) Å, Z = 4. The dimetallic unit has a Re-Re bond length of 2.264 (1) Å and an eclipsed conformation with the geminal chlorides in a cis configuration. The five-membered chelate rings have envelope conformations. © 1985, American Chemical Society. All rights reserved.
author list (cited authors)
Barder, T. J., Cotton, F. A., Dunbar, K. R., Powell, G. L., Schwotzer, W., & Walton, R. A.