Title

Boranometallacarboranes. 2. Crystal and Molecular Structures of [2,3-(C₂H₅)₂C₂B₄H₄]-5-Co[B₉H₁₂-1-O(CH₂)₄], [2,3-(CH₃)₂C₂B₃H₅]-5-Co[B₉H₁₂-1-O(CH₂)₄], and [1,2-(C₂H₅)₂C₂B₇H₇]-6-Co[B₉H₁₂-2-O(CH₂)₄]

Abstract

Full title: Boranometallacarboranes. 2. Crystal and molecular structures of [2,3-(C2H5)2C2B4H 4]-5-Co[B9H12-1-O(CH2)4], [2,3-(CH3)2C2B3H 5]-5-Co[B9H12-1-O(CH2)4], and [1,2-(C2H5)2C2B7H 7]-6-Co[B9H12-2-O(CH2)4]. X-ray crystallographic studies were conducted on the title compounds, which were obtained from reactions of 2,3-R2C2B4H5 - ions (R = CH3 or C2H5) with species formed from CoC12 and B5H8 - or B9H14 -, as described in the preceding article. Each complex incorporates both metallaborane and metallacarborane cages sharing a common metal atom, an arrangement not previously known. In all three species, the borane ligand is formally [B9,H12O(CH2)4]-, a derivative of B9H13 2- in which a tetrahydrofuran (THF) substituent displaces a terminal H-; the CoB9 cages are analogous to B10H14 with cobalt occupying the 5- or 6-position on the open face. The carborane ligands are different in the three compounds, such that the cobalt atom completes a 7-vertex closo-CoC2B4, a 6-vertex nido-CoC2B3, and a 10-vertex closo-CoC2B7 framework, respectively. In each case the borane and carborane ligands are arranged in a mutually twisted, unsymmetrical conformation, which appears to be a consequence of electronic factors rather than steric interaction between the ligands. In the (R2C2B7H7)Co(B9H 12·THF) complex, the 10-vertex CoC2B7 cage contains a long C-B bond [2.192 (9) Å], which creates a quasi-open face which may arise from the presence of electron density beyond the “normal” (2n + 2)-electron allotment in the skeletal bonding molecular orbitals of the cobaltacarborane. Crystal data: [2,3-(C2H5)2C2B4H 4]-5-Co[B9H12-1-O(CH2)4], mol wt 370.0, space group P21/n, Z = 4, a = 14.175 (4) Å, b = 9.032 (6) Å, c = 17.771 (3) Å, β = 112.12 (3)°, V = 2108 Å3, R = 0.038 for 2543 reflections having Fo 2 > 3σ(Fo 2); [2,3-(CH3)2C2B3H 5]-5-Co[B9,H121-O(CH2)4], mol wt 332.0, space group P21/n, Z = 4, a = 8.692 (2) Å, b = 9.658 (4) Å, c = 22.383 (9) Å, β = 97.51 (4)°, = V = 1863 Å3 R = 0.053 for 2370 reflections having Fo 2 > 3σ(Fo 2); [1,2-(C2H5)2C2B7H 7]-6-Co[B9H12-2-O(CH2)4], mol wt 405.3, space group P21/c, Z = 4, a = 13.166 (7) Å, b = 12.166 (5) Å, c = 14.786 (4) Å = 105.99 (5)°, V = 2277 Å3, R = 0.065 for 2426 reflections having Fo 2 > 3σ(Fo 2). © 1982 American Chemical Society.

Department(s)

Chemistry

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 1982 American Chemical Society (ACS), All rights reserved.


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