Seven-vertex Phosphinohalometallacarboranes of Iron, Cobalt, and Nickel: Syntheses, Structures, and Reactions

Abstract

The reaction of the nido-2,3-Et2C2B4H5 - ion with (Ph3P)2NiBr2 in THF at room temperature gave purple, crystalline 1-Br-1,5-(Ph3P)2-1,2,3-Ni(Et2C 2B4H3) (1), whose phosphino ligands are attached to nickel and boron, respectively. The same carborane ion reacted with (Ph2PCH2)2 and MCl2 (M = Co, Fe) in THF to give the crystalline metallacarboranes 1,1-(Ph2PCH2)2-1-Cl-1,2,3-M(Et 2C2B4H4) (2, M = Co; 3, M = Fe). Products 1-3 were structurally characterized by single-crystal X-ray diffraction and by IR, UV-visible, and mass spectra; in addition, high-field NMR spectra were obtained for the diamagnetic species 1 and 2, while paramagnetic 3 was examined via ESR and magnetic susceptibility measurements, which support the presence of low-spin Fe(III) in 3. The MC2B4 cages in all three compounds have normal closo seven-vertex (pentagonal-bipyramidal) geometry. Although 3 has one less electron than 2, its cage shows no significant distortion; hence, the unpaired electron appears to be localized in a nonbonding orbital on iron. The chlorine ligand in 2 was unaffected by NaH but was displaced by CN on treatment with KCN in refluxing CH3OH, giving 1,1-(Ph2PCH2)2-1-CN-1,2,3-Co(Et 2C2B4H4). The reaction of 2 with CH3MgI gave the iodo complex 1,1-(Ph2PCH2)2-1-I-1,2,3-Co(Et 2C2B4H4) as the only isolable metallacarborane product. The crystal structure determinations on 1, 2, and 3 are the first to be reported for metallacarboranes containing first-row transition-metal-halogen bonds Crystal data for 1: mol wt 792; space group P1Z = 2; a = 11.115 (4), b = 12.497 (5), c = 14.358 (8) Å; α = 90.34 (4), β = 94.57 (4), γ = 91.80 (2)°; V = 1987 Å3; R = 0.059 for 4741 reflections having F0 2 > 3σ(F0 2). Crystal data for 2: mol wt 622; space group P21; Z = 2; a = 8.311 (2), b = 15.357 (3), c = 12.635 (5) Å; β = 99.59 (2)°; V = 1590 Å3; R = 0.049 for 2285 reflections having F0 2 > 3σ(F0 2). Crystal data for 3: mol wt 619; space group P21; Z = 2; a = 8.307 (2), b = 15.310 (5), c = 12.540 (3) Å; β = 99.72 (2)°; V = 1572 Å3; R = 0.030 for 3352 reflections having F0 2 > 3σ(F0 2). © 1985 American Chemical Society.

Department(s)

Chemistry

International Standard Serial Number (ISSN)

0020-1669

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

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

Publication Date

01 Jan 1985

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