Pyrazolyl-Bridged Iridium Dimers.1 4. Crystal and Molecular Structures of Bis(cycloocta-1,5-diene)bis(μ-pyrazolyl)diiridium(I), Its Dirhodium(I) Isomorph, and Two Bis(cycloocta-1,5-diene)diiridium(I) Analogues Incorporating 3,5-Disubstituted µ-Pyrazolyl Ligands

Kathy A. Beveridge, Gordon W. Bushnell, Stephen R. Stobart, Jerry L. Atwood, Michael J. Zaworotko

Research output: Contribution to journalArticlepeer-review

Abstract

The crystal and molecular structures of the homobimetallic complexes [M(COD)(μ-pz)]2 (1, M = Ir, 2, M = Rh; COD = cycloocta-1,5-diene, pzH = pyrazole), [Ir(COD)(μ-fpz)]2 (3, fpzH = 3,5-bis(trifluoro-methyUpyrazole], and [Ir(COD)(μ-CH3,5-CF3C3N2H)]2 (4, derived from 3-methyl-5-(trifluoromethyl)-pyrazole) have been determined by single-crystal X-ray diffraction. Compounds 1 and 2 are isomorphous, crystallizing in the space group Cmcm with a = 12.750 (4) Å, b = 12.037 (4) Å, and c = 13.432 (4) Å and a = 12.745 (4) Å,b = 12.019 (4) Å, and c = 13.405 (4) Å, respectively; the two molecules are virtually identical with Ir-Ir = 3.216 (1) Å in 1 and Rh-Rh = 3.267 (2) Å in 2, indicating that observed differences in reactivity originate from electronic effects. Compound 3, space group PI with a = 11.604 (5) Å, b = 11.968 (5) Å, c = 11.131 (4) Å, α = 95.10 (4)°, β = 97.52 (4)°, and λ = 110.32 (3)°, is sterically crowded by the substituent CF3 groups in the µ-fpz unit in a way which accords with the remarkably inert character of this complex compared with 1 and which may also be responsible for the significant contraction in Ir-Ir, to 3.073 (1) Å. The structure of compound 4 is disordered in terms of CH3,CF3 site occupancy, but in this molecule also Ir-rr is short at 3.066 (2) A.

Original languageEnglish
Pages (from-to)1447-1451
Number of pages5
JournalOrganometallics
Volume2
Issue number10
DOIs
Publication statusPublished - Oct 1983
Externally publishedYes

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