Chiral complexes containing m-m quadruple bonds (m = molybdenum or rhenium) /
| Main Author: | |
|---|---|
| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1990.
|
| Subjects: | |
| Online Access: | Link to OAKTrust copy |
| Abstract: | Several complexes of the type Mo ₂X ₄(PP)₂ (X = Cl, Br or I; PP = R,R-diop, S,S-diop, S,S-bppm, dpcp or tetraphos-I) and Re₂Cl₆ (S,S-isodiop) will be reported. In Mo₂Cl₄ (R,R-diop)₂ , it is found that the structure is disordered so that while only one set of ligand atoms can be found, there are two incompletely occupied sets of metal atoms. The principal form (P), which is A-Mo₂CLi(R,R-diop)₂ , occupies 89% of the sites, while the secondary form (S), which is A-Mo₂Cl₄ (R,R-diop)₂ , occupies 11%. The P form has a twist angle of -78° and the S form has an angle of about 87°. The ¹H NMR spectrum shows that both the P and S molecules are present but in a P/S ratio of 1.7. The CD spectrum is found to be fully in accordance with the theoretical prediction that a Λ molecule with a twist angle 90° -χ will have the same signs for the CD bands as a Δ molecule with a twist angle χ. Both the complexes, β-Mo₂Cl₄(S,S-bppm)₂ and Re₂Cl₆ (S,S-isodiop) have an average twist angle of about 0° for the central portion. The one-electron static-coupling mechanism will be invoked to explain the CD spectra for these two complexes. It is found in the structure of Re2Cl₆ (S,S-isodiop) the diop ligand has been rearranged to give isodiop through a pathway similar to the acid-catalyzed rearrangements of acetals. The complexes β-Mo₂X₄(dpcp)₂ (X = Cl, Br, I) have the same twist angle (P-Mo-Mo-P) of about 22°, and in all these the Mo-Mo distance is 2.155 [5] A . Several interesting effects of the halogen atoms on the Mo-Mo bonds will be discussed. |
|---|---|
| Item Description: | Typescript (photocopy). Vita. "Major subject: Chemistry." |
| Physical Description: | xi, 147 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |