Reactivity studies of metalloporphyrins and metallotetraazaporphyrins / Yaping Ni.

Format:

Book

Manuscript

Microformat

Thesis/Dissertation

Author/Creator:

Ni, Yaping.

Contributor:

Wayland, Bradford B., advisor.

University of Pennsylvania.

Language:

English

Subjects (All):

Penn dissertations--Chemistry.

Chemistry--Penn dissertations.

Local Subjects:

Penn dissertations--Chemistry.

Chemistry--Penn dissertations.

Physical Description:

xvii, 205 pages : illustrations ; 29 cm

Production:

1997.

Summary:

This dissertation focuses on reactivity studies of metalloporphyrins and metallotetraazaporphyrins.

A series of octaethyltetraazaporphyrinato rhodium, (OETAP)Rh, complexes were prepared for comparative studies with the corresponding octaethylporphyrinato rhodium, (OEP)Rh, derivatives. ((OETAP)Rh) $\sb2$ (1) reacts like ((OEP)Rh) $\sb2$ (2) with CH$\sb3$I, CH$\sb3$NC, (CH$\sb3$O)$\sb3$P and CH$\sb2$=CH$\sb2$, but reactions of 1 are invariably much slower than those for 2. ((OETAP)Rh) $\sb2$ fails to react with H$\sb2$, CO, CH$\sb3$CHO, CH$\sb3$C$\sb6$H$\sb5$ which are prominent substrate reactions for 2. Reactivity and equilibrium studies indicate that a substantially larger Rh-Rh bond dissociation enthalpy for 1 compared with 2 is primarily responsible for the slower rates and reduced scope of substrate reactions for ((OETAP)Rh) $\sb2.$ Dissolution of 1 in pyridine results in formation of a persistent OETAP anion radical complex of Rh(III), (OETAP$\sp{\cdot -}$)Rh$\sp{\rm III}$(py)$\sb2$, which contrasts with 2 where disproportionation produces (OEP)Rh$\sp{\rm I}$ anion and (OEP)Rh$\sp{\rm III}$(py)$\sb2$ cation. (OEP) pi cation radical complexes ((OEP)M$\sp\cdot\rbrack\sp+$ or their dimers of Rh and Co were formed when reacting (OEP)Co and (OEP)Rh-I with AgBF$\sb4$, and ((OEP)$\sp\cdot$Co) $\sp+$BF$\sb4\sp-$ were identified as containing a porphyrin a$\sb{\rm 1u}$ radical cation. No evidence was obtained for the (OETAP) pi-cation radical species in the analogous reactions. The X-ray crystal and molecular structure determination for (OETAP)Rh-CH$\sb3$ reveals a smaller hole size and corresponding shorter Rh-N distances for the (OETAP)Rh derivative in comparison with (OEP)Rh-CH$\sb3.$ Differences in the structure and reactivity of (OETAP)M and (OEP)M complexes are discussed in terms of the smaller hole size and lower energy of the HOMO/LUMO orbitals of the OETAP ligand.

Cobalt(II) porphyrins react with organic radicals ($\cdot$C(CH$\sb3$)(R)X) by $\beta$-hydrogen abstraction to form a transient cobalt hydride, which adds to fluoroalkenes to form fluoroalkyl cobalt porphyrin complexes. Addition of (por)Co-H to fluoroalkenes were found to occur with high regioselectivity corresponding to formation of the most stable fluoroorganic radicals. Crystal structure of (OEP)Co-CFCICF$\sb2$H shows M-C bond shortening in fluoroalkyl metal complex compared to alkyl metal analogues. Photolysis of (TMP)Co-Rf produces (TMP)Co and $\cdot$R$\sb{\rm f}$, which can initiate and control the polymerization of methyl acrylate.

Notes:

Supervisor: Bradford B. Wayland.

Thesis (Ph.D. in Chemistry) -- University of Pennsylvania, 1997.

Includes bibliographical references.

Local Notes:

University Microfilms order no.: 98-14894.

OCLC:

187457362