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 2422 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) , b = 12.849 (4) , c = 38.691 (9) , = 85.96 (2), V= 5776 (43) 3, 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 [1], and the Re-Re bond length is 2.234 (3) . Re2Cl4(dmpe)2.CH3OH (2) was isolated and crystallized as the isomer, viz., with the dmpe ligands chelating. The crystallographic parameters are as follows: Re2Cl4P4OC13H36; orthorhombic, Ccma (nonstandard setting of Cmca); a = 11.595 (2) , b = 14.475 (2) , c = 14.925 (2) , V= 2505 (1) , Z = 4. The dimetallic unit has a Re-Re bond length of 2.264 (1) 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.
