In this study, the effect of a donor ligand on the stabilization of a carbonyl pyrazine tungsten complex was studied. The pentacarbonylpyrazinetungsten(0) complex could be formed from the photolysis of hexacarbonyltungsten(0) in the presence of pyrazine and could be isolated as crystalline solid. However, the complex was found to be unstable in solution, being converted to a bimetallic complex, (CO)5W(pyz)W(CO)5 and free pyrazine molecule. Two complexes exist in solution at equilibrium. The equilibrium constant could be determined by 1H-NMR spectroscopy and found to be 0.0396 at 25&deg / C. To test whether the introduction of a second pyrazine ligand might provide stability for the carbonyl-pyrazine-tungsten complex, W(CO)4(pyz)2 was attempted to be synthesized. The cis-W(CO)4(pyz)2 complex could be generated from the thermal substitution reaction of cis-W(CO)4(piperidine)2 with excess pyrazine in dichloromethane. However, this complex could not be isolated because of the lack of stability. The complex could only be identified by IR spectroscopy in solution. To stabilize the pentacarbonylpyrazinetungsten(0) complex, trimethylphosphite was introduced to the complex as a donor ligand. For this purpose, cis-W(CO)4[P(OCH3)3](thf), photogenerated from W(CO)5[P(OCH3)3] in tetrahydrofuran (thf), was reacted with pyrazine. The replacement of tetrahydrofuran with pyrazine (pyz) yielded cis-W(CO)4[P(OCH3)3](pyz). The complex could be isolated from the reaction solution and characterized by means of IR, 1H-, 13C-, 31P-NMR, and Mass spectroscopies. The introduction of P(OCH3)3 has proved that a donor ligand will strengthen the metal-pyrazine bond and thus stabilizes the complex. As a result of this stabilization, the complex could be isolated as the first example of tungsten pyrazine complexes that contain a donor ligand.

Pentacarbonylacryloylferrocenetungsten(0) complex was synthesized photochemically from hexacarbonyltungsten(0) and acryloyferrocene (acfc). UV irradiation of W(CO)6 in the presence of acryloylferrocene at 10 oC for 4 hours in n-hexane solution generates the W(CO)5(&amp / #61544 / 2-acfc) complex as the sole monosubstitution product of the photolysis, as monitored by FT-IR spectroscopy. The product complex could be isolated from the reaction solution and characterized by IR, Raman, 1H-NMR, 13C-NMR spectroscopies, mass spectrometry and elemental analysis. The complex was found to be unstable in solution and to decompose to the parent W(CO)6 complex and free acryloylferrocene molecule. The instability of the complex makes its isolation as analytically pure substance difficult. In order to stabilize the tungsten-olefin bond, trimethylphosphite was introduced as a donor ligand into the molecule. Thus, a complex containing a donor ligand in addition to the olefinic ligand was prepared starting with W(CO)6, trimethylphosphite, and acryloylferrocene. UV irradiation of W(CO)5[P(OMe)3] with acryloylferrocene in n-hexane solution at room temperature generates W(CO)4[P(OMe)3](&amp / #61544 / 2-acfc), which was isolated from the reaction solution and characterized by IR, 1H-NMR, 13C-NMR spectroscopies and mass spectrometry. The complex was found to have a cis arrangement of four CO groups in the pseudo-octahedral geometry. However, the cis-W(CO)4[P(OMe)3](&amp / #61544 / 2-acfc) complex was found to be less stable than W(CO)5(&amp / #61544 / 2-acfc).

Bibliography: leaves 317-318 / 318 leaves (some folded) : ill ; 31 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physical and Inorganic Chemistry, 1983

Typescript (photocopy) / 2 microfiche in end pocket / 190 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physical and Inorganic Chemistry, 1984

Thesis (Ph. D.)--University of Adelaide, Dept. of Physical and Inorganic Chemistry, 1983. / Includes bibliographical references (leaves 317-318).

Thesis (Ph. D.)--University of Adelaide, 1985. / Includes bibliographical references (leaves 204-208).

Thesis (Ph. D.)--University of Hong Kong, 2007. / Also available in print.

Thesis (Ph.D.) -- University of Adelaide, Dept. of Physical and Inorganic Chemistry, 1984. / Typescript (photocopy). 2 microfiche in end pocket.

Thesis (M.Sc. (Organic Chemistry))--Mahidol University, 1984.

Thesis (Ph. D.)--University of Hong Kong, 1999. / Includes bibliographical references.