Abstract
Ph.D.
This study comprises the preparation and characterization of new carbene complexes of iron,
molybdenum, gold, copper and silver from azolyl and thienyl precursors. In addition, the
syntheses of aminoacyl chelate and metallacyclic iron compounds as well as unique 6-membered
dimeric and 18-membered trimeric thienyl gold compounds are reported. Furthermore,
di(vinyl)carbene complexes, which are not yet known for gold and which are very rare for most
other metals, are also described.
In contrast to most other carbene complexes that result from precursors in which the heteroatom
is situated a or y to the coordinated carbon atom, the new amino(organo)-, organo(thio)- and
di(organo) carbene complexes are unique in that they have been prepared from azolyl or thienyl
precursors in which the nucleophilic heteroatom is located outside the coordinated ring system
and is separated from the coordinated carbon by several bonds.
The complex [CpFe(CO)2C1] reacts with lithiated pyrazole, (thienyl)oxazoline or (thienyl)pyridine
to form precursor pyrazolyl and thienyl iron(II) compounds which upon alkylation or protonation
with CF3SO3Me or CF3SO3H afford amino(organo)-, organo(thio)- or heterometallacyclic
alkoxy(amino)- and hydroxy(amino)carbene complexes as well as compounds which show
pyridinium character. The heterometallacyclic complexes incorporate unusual ferropyridine or
ferropyrole rings. ' 3C-{'}I} NAIR data of the above compounds show that the coordinated
carbons of the azolyl and thienyl ligands are significantly affected upon carbene formation,
although an X-ray crystallographic investigation indicates that carbene formation has little if any
effect on bond distances in the azolyl ligand when it becomes a coordinated azolinylidene. The
molecular structures of the pyrazolyl complex [CpFe(C0) 2{C=CHCH=NNPh}], the
pyrazolinylidene complex [CPFe(C0) 2{CCHHNHI4P11}1[CF3S03], the 2-(2'-oxazolinyl)thien-
5-ylidene complex [CpFe(C0)2{CCHHC(1\1HCMe2CH26)}1[CF3S03] and the
heterometallacyclic complex [CpFe(C0){CC(=&CMe 2CH2(5)SCH---9-1)] indicate small
variations in iron-carbon distances of 1.981(2), 1.969(5), 1.99(1) and 1.959(7) A. Four equivalents of 2-(4',5'-dihydro-4',4'-dimethy1-2'-oxazolinyl)thien-3-yllithium reacts with the
acetate [Mo2(O2CMe)4] to form the stable, neutral, quadruply bonded dimolybdenum complex
[Mo2{C=C(6=NCMe2CH26)SCH2CH2} 2(02CMe)2], while 4-methylthiazoly1 lithium reacts with
the same acetate to form the unstable, thiazolyl molybdate [Mo 2{6=NCMe—Cfg} 8]4".
Reaction of [AuCI(tht)] (tetrahydrothiophene) with 2-(4',5'-dihydro-4',4'-dimethy1-2'-oxazoliny1)-
thien-3-yllithium or 2-(4',5'-dihydro-4',4'-dimethy1-2'-oxazolinyl)thien-5-yllithium afforded
dimeric and trimeric thienyl oligomers of gold(I). The molecular structure of the six-membered
dimeric compound [Au{C=C(=NCMe 2CH2O)SCH=CH}li shows a Au...Au separation of
2.8450(6)A, while such interactions are absent in the trimeric compound
[Au{C=C(C=NCMe2CH2O)SCH=CH}] 3 . Protonation of the former compound as well as the
stable monomers obtained from [Au(tht)C 6F5] or [Au(Cl)PPh 3J afforded unique di(vinyl)carbene
as well as imine complexes. Reaction of 2-(2'-pyridyl)thien-5-yllithium with [Au(COPPh 3] and
subsequent alkylation yields an organo(thio)carbene compound.
Finally, a series of cationic copper(I) bis(carbene) complexes were formed upon sequential
treatment of copper(I) trifluoromethanesulfonate with thiazolyl- or pyrazolyllithium and
CF3SO3Me. A similar reaction with 4-methylthiazol-2-yllithium and silver triflate produced the
first amino(thio)carbene complex of silver.