Doctoral Dissertations

Abstract

"As part of a project directed towards elucidating the characteristics of ligands which coordinate to give complexes having tetrahedral structures, a study of chelates containing the bulky quinuclidine group has been made. With 2-(N-morpholinylmethyl)-3-quinuclidinone (MQN), complexes having the general formula M(MQN)X₂ were prepared where the metal ion was Co(II), Ni(II), Fe(II), Cu(II), and Mn(II). The ligands 2-(N-piperidinylmethyl)-3-quinuclidinone (PQN) and 2-(N-dimethylaminomethyl)-3-quinuclidinone (DQN) were prepared along with the analogous cobalt(II) chloride complexes. The series of complexes Co(MQN)X₂ where X = Cl, Br, or I were prepared, and magnetic susceptibilities and spectral data obtained. They have room temperature magnetic moments in the range 4.66-4.85 with slight decreases at lower temperatures. Spectral parameters derived from their electronic absorption spectra are typical of tetrahedrally coordinated Co(II) ions with Dq varying between 390-430 cm⁻¹ in the solid phase. Band assignments corresponding to spin-allowed d-d transitions were made. Properties of Co(MQN)Cl₂, Co(PQN)Cl₂, and Co(DQN)Cl₂ show distortion from tetrahedral symmetry in the order MQN < PQN < DQN in the solid phase and PQN < MQN ~ DQN in solution. Infrared spectra are essentially identical for the MQN series and tentative Co-X stretching frequencies are given. The complex Co(MQN)(NCS)₂ · C₂H₅OH is octahedrally coordinated by virtue of bridging thiocyanate groups. A value of µeff of 4.38 was found for this compound and band assignments yield 970 cm⁻¹ for Dq in pure Oh symmetry. A series of nickel complexes, viz., Ni(MQN)X₂ where X = Cl, Br, or I were obtained by the addition of the appropriate metal salt to MQN. Two forms of a complex of general formula Ni(MqN)Cl₂ were prepared and characterized. The purple Ni(MQN)Cl₂ analog along with the corresponding purple bromide and green iodide were found to have pseudotetrahedral symmetries. Magnetic susceptibility data at 300º K give µeff values between 3.35 and 3.58 for these compounds. Further data were obtained from room temperature to 18º K for the three halide complexes and these show a slight decrease in µeff for Ni(MQN)Br₂, a slight increase in µeff for purple Ni(MQN)Cl₂, and a sharp increase in µeff for Ni(MQN)I₂ below 50º K. Some of the low temperature moments were found to be dependent upon the strength of the magnetic field. Band assignments were made and calculation of spectral parameters yield Dq values in the solid phase ranging from 525 to 550 cm⁻¹. The electronic absorption spectrum of Ni(MQN)Br₂ at 25º and 300º K is reported and tentative Ni-X stretching frequencies are given. In contrast to the purple, pseudotetrahedral Ni(MQN)Cl₂, an off-white compound of the same formula was prepared and characterized. This off-white analog contains octahedrally coordinated nickel atoms by virtue of halogen bridging. µeff is 3.40 at room temperature and Dq is found to be 1000 cm⁻¹. Low temperature electronic absorption spectra and infrared data the range 600-200 cm⁻¹ are given. Compounds having the formulas Ni(MQN)(NCS)₂ · CH₃OH and Ni(MQN)(NO₃)₂ were found to have octahedral symmetries about the central metal atom. The thiocyanate complex is believed to contain bridging and terminal thiocyanate groups and a structure similar to that of Co(MQN)(NCS)₂ · C₂H₅OH is proposed. The nitrate complex contains bridging or chelating nitrate groups. Room temperature µeff is 3.23 and Dq is 970 cm⁻¹ for Ni(MQN)(NCS)₂ · CH₃OH. These parameters are, respectively, 3.33 and 950 cm⁻¹ for Ni(MQN)(NO₃)₂. The only iron(II) complex obtained was Fe(MQN)Cl₂ and this has a pseudotetrahedral structure. The electronic absorption spectrum shows a broad, asymmetric band at about 6700 cm⁻¹ assigned to the ⁵E→⁵T₂ transition in pure Td symmetry. µeff is 5.27 at 294º and is essentially independent of temperature, as expected. The Mössbauer parameters ΔEQ and δ are 2.74 mm/sec and 0.91 mm/sec, respectively, at 300º K. Two manganese(II) complexes are reported, viz., Mn(MQN)Cl₂ and Mn(MQN)Br₂. Electronic absorption spectral bands could not be observed and values of µeff were not helpful in deducing the structures of these compounds. A comparison of d-spacings obtained for the Mn(II) complexes with the corresponding Ni(II) and Co(II) complexes was not useful. The series of complexes Cu(MQN)X₂ where X= Cl, Br, or NO₃ have been prepared and each was found to exhibit a broad band in the electronic absorption spectrum as is usually found in Cu(II) complexes. Values of µeff were found in the range 1.83-1.89 and showed essentially no dependence upon temperature. Comparison of X-ray diffraction data with analogous Co(II) and Ni(II) compounds and examination of Cu-X stretching frequencies suggested pseudotetrahedral structures for the chloride and bromide complexes. The nitrate complex is most likely octahedrally coordinated through bridging or chelating nitrate groups. Confirmation of these structures must await an X-ray crystallographic study. Perchlorate complexes of several metal(II) compounds were prepared. The cobalt, nickel, and copper complexes were found to contain two MQN ligands in the coordination spheres. Some of the complexes were hydrates. µeff was found to be 4.36 for Co(MQN)₂(ClO₄)₂; 4.02 for Ni(MQN)₂(ClO₄)₂ · 4H₂O; 1.98 for Cu(MQN)₂ (ClO₄)₂. All of the perchlorate complexes appeared to be tetrahedrally coordinated with two nitrogen-coordinated ligands."--Abstract, pages ii-v.

Advisor(s)

Long, Gary J., 1941-

Committee Member(s)

Tappmeyer, Wilbur P.
Webb, William H.
Venable, Raymond L., 1935-2008
Mayhan, Kenneth G.

Department(s)

Chemistry

Degree Name

Ph. D. in Chemistry

Publisher

University of Missouri--Rolla

Publication Date

1972

Pagination

xii, 107 pages

Note about bibliography

Includes bibliographical references (pages 99-103).

Rights

© 1972 Richard Cecil Dickinson, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Subject Headings

Chelates -- Analysis
Metal catalysts
Ligands

Thesis Number

T 2637

Print OCLC #

6039010

Electronic OCLC #

878051219

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