Carbon-rich Metallacarboranes. 14. Synthesis and Structure of Mixed-ligand Cobalt and Iron Complexes Derived from (C2H5)4C4B8H 8 2- and (C2H5)2C2B4H 5 -


The preparation of metallacarboranes having Et4C4B8H8 2- and Et2C2B4H4 2- ligands bound to a common metal center was explored via reactions of Et4C4B8H8 2- ion with CoCl2 or FeCl2 in tetrahydrofuran followed by addition of Et2C2B4H5 -. In the cobalt reaction the main products were purple (Et2C2B4H4)Co(Et4C 4B8H7OC4H8) (6a) and red-brown (Et2C2B4H3)Co(EtC4B 8H6OC4H8) (7) with small amounts of (Et4C4B8H7)2CoH (4b), (Et4C4B8H7)2Co 2 (2b), (Et4C4B8H8)2CoH(OC 4H8) (3b), and Et6C6B12H12 (8). The corresponding iron reaction gave primarily red (Et2C2B3H4)FeIIIH(Et 4C4B8H7) (11), with minor products (Et2C2B4H4)FeIII(Et 4C4B8H8OC4H8) (9a,b) and (Et2C2B4H3)FeIIH 2(Et4C4B8H7) (10). From spectroscopic evidence, 4b, 7, 10, and 11 are proposed to have direct interligand bonds. An X-ray crystallographic study of 6a confirmed the presence of closo-CoC2B4 and nido-CoC4B8 cages joined at a common cobalt vertex, with a THF substituent on the larger cage. The 13-vertex CoC4B8 system has the shape of a 14-vertex closo polyhedron (bicapped hexagonal antiprism) with an equatorial vertex missing and, except for the metal location, is analogous to the structure reported earlier for [(C6H5)2PCH2]2NiMe 4C4B8H8. Both cage systems in the molecule conform to the skeletal electron-counting rules for polyhedral cages. Crystal data: [(C2H5)2C2B4H 4]Co[(C2H5)4C4B 8H7OC4H8], Mr = 518, space group P21/c, a = 11.418 (5) Å, b = 14.639 (3) Å, c = 17.487 (8) Å, β = 100.74 (3)°, V = 2872 Å3, Z = 4, R = 0.057 for 2013 reflections having Fo 2 > 3σ(Fo 2). © 1985 American Chemical Society.



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© 1985 American Chemical Society (ACS), All rights reserved.

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01 Jan 1985