Title

Organotransition-metal Metallacarboranes 4

Alternative Title

Stable η⁸-C₈H₈ and η⁷-C₇H₇ complexes of titanium, vanadium, and chromium: synthesis and crystal structures of (η⁸-C₈H₈)M(Et₂C₂B₄H₄) (M = Ti, V) and (η⁷-C₇H₇)Cr(Et₂C₂B₄H₄)

Abstract

Full title: Organotransition-metal metallacarboranes. 4. Stable η8-C8H8 and η7-C7H7 complexes of titanium, vanadium, and chromium: Synthesis and crystal structures of (η8-C8H8)M[(C2H 5)2C2B4H4] (M = Ti, V) and (η7-C7H7)Cr[(C2H 5)2C2B4H4]. The reactions of C8H8 2- and (C2H5)2C2B4H 5 - ions with TiCl3 and VCl3 in THF gave as the major isolable products (η8-C8H8)Ti[(C2H 5)2C2B4H4] (1) and (η8-C8H8)V[(C2H 5)2C2B4H4] (2) respectively. In the corresponding reaction of CrCl3, no cyclooctatetraene complex was isolated; however, (η7-C7H7)Cr[(C2H 5)2C2B4H4] (3) was obtained in low yield. Complexes 1-3 were characterized spectroscopically and via X-ray crystal structure determinations. All three structures consist of a closo seven-vertex pentagonal-bipyramidal MC2B4 metallacarborane cage with the metal coordinated to a planar η8-C8H8 ligand in 1 and 2 and to a planar η7-C7H7 ligand in 3. Complexes 1-3 are indefinitely air-stable in the solid state; 2 and 3 exhibit no sensitivity to oxygen even in solution. The titanium complex 1 reacts with CH3I/AlCl3 to give the 5-iodo derivative and with I2 in benzene to give the 4,5-diiodo derivative. Magnetic susceptibility and ESR studies of the vanadium complex 2 support the assignment of V(IV), but the low-temperature ESR spectrum does not exhibit hyperfine structure attributable to vanadium-boron interaction. Crystal data: complex 1, Mr = 282, space group Pna21, Z = 4, a = 14.309 (3) Å, b = 12.660 (2) Å, c = 8.476 (2) Å, V = 1535 Å3, R = 0.049 for 1902 reflections having Fo 2 > 3σ(Fo 2); complex 2, Mr = 286, space group Pna21, Z = 4, a = 14.264 (5) Å, b = 12 595 (4) Å, c = 8.449 (2) Å, V = 1518 Å3, R = 0.047 for 1271 reflections having Fo 2 > 3σ(Fo 2); complex 3, Mr = 273, space group Pna21, Z = 4, a = 14.334 (3) Å, b = 12.230 (4) Å, c = 8.356 (1) Å, V = 1465 Å3, R = 0.065 for 1289 reflections having Fo 2 > 3σ(Fo 2). © 1984 American Chemical Society.

Department(s)

Chemistry

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 1984 American Chemical Society (ACS), All rights reserved.


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