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Synthesis, Properties, and Reaction Behavior of Cobalt and Copper Organometallic Complexes with Chelating Ligands

Zhang, Baoxin (2013)
Synthesis, Properties, and Reaction Behavior of Cobalt and Copper Organometallic Complexes with Chelating Ligands.
Technische Universität Darmstadt
Dissertation, Erstveröffentlichung

Kurzbeschreibung (Abstract)

Several cobalt complexes with tripodal chelating ligands Tp and Tp* (Tp = tris(pyrazolyl)borate; Tp* = tris(3,5-dimethyl-pyrazolyl)borate) were synthesized by treating the homoscorpionates of the first generation with CoBr2 under different conditions. These complexes were characterized with X-ray crystallographic determination as well as IR, NMR, MS, and UV-vis spectroscopies. Reaction of KTp with CoBr2 in THF afforded an unprecedented trinuclear Co(II) complex [TpCo(Hpz)Br]2(CoBr2) (1) with Tp as terminal ligands, as well as an oxidized side-product (Tp2Co)(Co2Br6) (2). The terminal Co(II) centers of (1) are octahedrally coordinated while the Co(II) in the bridging unit has a distorted tetrahedral geometry, holding a neighboring Co···Co distance of 3.472 Å. Reaction of KTp* with CoBr2 afforded half-sandwich Tp*CoBr (4) with pseudotetrahedrally coordinated Co(II) center, which is accessible to other donors. Mononuclear Tp*CoSPh (7) and dinuclear (Tp*Co)2O2(pz)2 (8) were prepared through ligand exchange reactions of LiSPh and Li(pz) with (4), respectively. (8) contains two octahedral Co(III) centers bridged by two pyrazolyl and a peroxide groups, in which the Co···Co distance is 3.591 Å.

Reaction of (dppf)Cu(NCMe) (dppf = 1,1’-bis(diphenylphosphino)ferrocene) with chloranilate dianion (CA2-) afforded tetranuclear complex (dppf)2Cu2(CA) (9). Single crystal X-ray diffraction revealed that the Cu(I) centers are coordinated by dppf and CA2- in a distorted-tetrahedral manner. The two Cu(I) centers are located almost in the same plane of the bridging ligand with the Cu···Cu separation of 7.940 Å. In its UV-Vis spectrum, the π−π∗ and n−π∗ absorptions of CA2- bridge are shown at 297.1 nm and 480.4 nm, respectively. Irreversible reduction waves were illustrated in the cyclic voltammogram of (9), which were attributed to an ECE process during the measurement.

Typ des Eintrags: Dissertation
Erschienen: 2013
Autor(en): Zhang, Baoxin
Art des Eintrags: Erstveröffentlichung
Titel: Synthesis, Properties, and Reaction Behavior of Cobalt and Copper Organometallic Complexes with Chelating Ligands
Sprache: Englisch
Referenten: Schneider, Prof. Dr. Jörg J. ; Klein, Prof. Dr. Hans-Friedrich
Publikationsjahr: 11 März 2013
Datum der mündlichen Prüfung: 29 April 2013
URL / URN: http://tuprints.ulb.tu-darmstadt.de/3683
Kurzbeschreibung (Abstract):

Several cobalt complexes with tripodal chelating ligands Tp and Tp* (Tp = tris(pyrazolyl)borate; Tp* = tris(3,5-dimethyl-pyrazolyl)borate) were synthesized by treating the homoscorpionates of the first generation with CoBr2 under different conditions. These complexes were characterized with X-ray crystallographic determination as well as IR, NMR, MS, and UV-vis spectroscopies. Reaction of KTp with CoBr2 in THF afforded an unprecedented trinuclear Co(II) complex [TpCo(Hpz)Br]2(CoBr2) (1) with Tp as terminal ligands, as well as an oxidized side-product (Tp2Co)(Co2Br6) (2). The terminal Co(II) centers of (1) are octahedrally coordinated while the Co(II) in the bridging unit has a distorted tetrahedral geometry, holding a neighboring Co···Co distance of 3.472 Å. Reaction of KTp* with CoBr2 afforded half-sandwich Tp*CoBr (4) with pseudotetrahedrally coordinated Co(II) center, which is accessible to other donors. Mononuclear Tp*CoSPh (7) and dinuclear (Tp*Co)2O2(pz)2 (8) were prepared through ligand exchange reactions of LiSPh and Li(pz) with (4), respectively. (8) contains two octahedral Co(III) centers bridged by two pyrazolyl and a peroxide groups, in which the Co···Co distance is 3.591 Å.

Reaction of (dppf)Cu(NCMe) (dppf = 1,1’-bis(diphenylphosphino)ferrocene) with chloranilate dianion (CA2-) afforded tetranuclear complex (dppf)2Cu2(CA) (9). Single crystal X-ray diffraction revealed that the Cu(I) centers are coordinated by dppf and CA2- in a distorted-tetrahedral manner. The two Cu(I) centers are located almost in the same plane of the bridging ligand with the Cu···Cu separation of 7.940 Å. In its UV-Vis spectrum, the π−π∗ and n−π∗ absorptions of CA2- bridge are shown at 297.1 nm and 480.4 nm, respectively. Irreversible reduction waves were illustrated in the cyclic voltammogram of (9), which were attributed to an ECE process during the measurement.

Alternatives oder übersetztes Abstract:
Alternatives AbstractSprache

Diverse Kobaltkomplexe mit den tripodalen Chelatliganden Tp und Tp* (Tp = tris(pyrazolyl)borat; Tp* = tris(3,5-dimethyl-pyrazolyl)borat) wurden durch Umsetzung von Homoscorpionaten des ersten Generation mit CoBr2 unter verschiedenen Bedingungen dargestellt. Diese Komplexe wurden sowohl kristallstrukturanalytisch als auch durch IR, NMR, MS, und UV-vis-Spektroskopie charakterisiert. In der Reaktion von KTp mit CoBr2 in THF wurde der neue dreikernige Co(II)-Komplex [TpCo(Hpz)Br]2(CoBr2) (1) sowie das oxidierte Nebenprodukt (Tp2Co)(Co2Br6) (2) erhalten. Während die terminalen Co(II)-Zentren in (1) oktaedrisch koordiniert sind, zeigt die verbrückende Co(II)-Einheit eine verzerrte tetraedrische Geometrie, wobei der Co···Co-Abstand 3.472 Å beträgt. In der Reaktion von KTp* mit CoBr2 wurde dagegen der Halbsandwichkomplex Tp*CoBr (4) mit pseudotetraedrisch koordiniertem Co(II)-Zentrum erhalten, welches dem Angriff von anderen Donormolekülen zugänglich ist. So wurden der einkernige Komplex Tp*CoSPh (7) sowie der zweikernige Komplex (Tp*Co)2O2(pz)2 (8) durch Ligandenaustauschreaktion von (4) mit LiSPh bzw. Li(pz) gebildet. (8) enthält zwei oktaedrisch koordinierte Co(III)-Zentren, die durch zwei Pyrazolyleinheiten und eine Peroxidgruppe verbrückt sind, wobei der Co···Co-Abstand 3.591 Å beträgt.

In der Reaktion von (dppf)Cu(NCMe) (dppf = 1,1'-bis(diphenylphosphino)ferrocen) mit dem Chloranilat-Dianion (CA2-) bildete sich der vierkernige Komplex (dppf)2Cu2(CA) (9). Eine Kristallstrukturanalyse zeigt, dass die Cu(I)-Zentren in (9) durch dppf und CA2- verzerrt-tetraedrisch koordiniert sind. Die beiden Cu(I)-Zentren befinden sich nahezu in der Ebene des verbrückenden CA-Ligands, wobei der Cu···Cu-Abstand 7.940 Å beträgt. Im UV-vis-Spektrum wurden die den π−π∗ und n−π∗-Übergängen der CA2--Brücke zugeordneten Absorptionsmaxima bei 297.1 nm bzw. 480.4 nm registriert. Eine cyclovoltammetrische Analyse von (9) ergab lediglich irreversible Reduktionswellen, die ECE-Prozessen zugeordnet wurden.

Deutsch
URN: urn:nbn:de:tuda-tuprints-36832
Sachgruppe der Dewey Dezimalklassifikatin (DDC): 500 Naturwissenschaften und Mathematik > 540 Chemie
Fachbereich(e)/-gebiet(e): 07 Fachbereich Chemie
07 Fachbereich Chemie > Eduard Zintl-Institut > Fachgebiet Anorganische Chemie
Hinterlegungsdatum: 08 Dez 2013 20:55
Letzte Änderung: 08 Dez 2013 20:55
PPN:
Referenten: Schneider, Prof. Dr. Jörg J. ; Klein, Prof. Dr. Hans-Friedrich
Datum der mündlichen Prüfung / Verteidigung / mdl. Prüfung: 29 April 2013
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