Dissertation > Mathematical sciences and chemical > Chemistry > Physical Chemistry ( theoretical chemistry ),chemical physics > Structural Chemistry > Complex chemistry ( coordination chemistry )

Containing new synthetic methods and reactivity studies of rare earth compounds of the machine sulfur ligands

Author LiYanRong
Tutor ZhouXiGeng
School Fudan University
Course Organic Chemistry
Keywords Elemental sulfur Insertion reaction Bis (cyclopentadienyl) rare - earth alkyl compounds (Cyclopentadienyl) rare-earth hydrocarbon sulfur-based compounds (Cyclopentadienyl) rare-earth sulfur compounds (Cyclopentadienyl) Rare Earth , sulfur compounds Synthesis Crystal structure
CLC O641.4
Type PhD thesis
Year 2005
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The synthesis and transformation of lanthanide complexes containing sulfur-based ligands are receiving increasing attention for both fundamental interest and potential applications in catalysts and materials science. Presently lanthanide thiolate complexes have been prepared by either classical metathetical reactions or by oxidation addition of organic disulfides to low-valent lanthanide species. Insertion reaction of metal-ligand bonds are powerful tools for the construction of ancillary ligands in organolanthanide chemistry, although tellurium and selenium insertion into a lanthanide-carbon bond proved to be feasible 10 years ago, surprisingly no example of the formation of thiolate ligands by the insertion of elemental sulfur into the lanthanide-carbon σ-bond has been reported.Furthermore, very little is known about the reactivity of lanthanocene thiolates in comparison with containing C- or N-based anion. In continuation of our studies on insertion into lanthanide-ligand bonds, we are especially interested to determine if thilolate complexes of rare earths may be synthesized by sulfur insertion into organolanthanide alkyls, because the latter route has significant advantages in that it avoids the synthesis of the intermediate organosulfurs and gives potentially easy access or inaccessible by other routes. In this thesis, we firstly study the activation of organolanthanide on elemental sulfur, by which twenty-one new organolanthanide complexes are synthesized. This thesis consists of five chapters. The details are as follows:In chapter I, preface, the development of organolanthanide complexes containing sulfur ligands in recent years is summarized.In Chapter II, we have demonstrated that organolanthanide alkyl complexes exhibit high activity toward elemental sulfur. Elemental sulfur inserts readily into the Ln-C σ-bonds of (C5H52LnR (R = Me, nBu) under mild conditions, giving organolanthanide thiolate complexes [(C5H52LnSR]2 (R = Me, Ln = Yb (1), Y (2), Er (3), Dy (4); R = nBu, Ln = Y (5), Er (6), Dy (7)) which offer a novel method for synthesis of organolanthanide thiolate complexes. The organolanthanide thiolate complexes are unstable in sulution with S8, allowing a mild and efficient transformation into lanthanocene sulfides [(Cp2Ln)2(μ3-S)(THF)]2 (Ln = Y (8), Yb (9)) and disulfides [Cp2Yb(THF)]2(μ-η22-S2) (10). The present results would seem tooffer a new route to generate lanthanocene sulfide and disulfido complexes, which still remains undeveloped due to the lack of a general synthetic approach.Complexes 1-10 were characterized by elemental analysis, IR, and mass spectroscopies. Structures of complexes 1, 5, 6, 8, 9 and 10 were also confirmed by the X-ray crystal structure analysis. The crystal structural data proves that only one sulfur atom was inserted into the lanthanide-carbon bond.In Chapter III, We continued to study on the factors affecting on sulfur insertion reactions by modifying cyclopentadienyl with tert-butyldimethylsilyl and we synthesized organolanthanide thiolate compounds [(C5H4SiMe2tBu)2Ln(μ-SMe)]2 [Ln = Yb (15), Y (16), Dy (17), Er (18)]. Unlikely the insertion reaction of elemental sulfur into lanthanide-carbon of Cp2LnnBu, We have obtained the organolanthanide compounds [(C5H4SiMe2tBu)2Ln(μ-SnBu)]2 [Ln = Y (19), Dy (20), Er (21)] at room temperature. The results proved that steric hindrance factor can affects the insertion of sulfur into the lanthanide-carbon, and restrain the transformation from organolanthanide thiolate complexes to lanthanocene sulfides or disulfides.In Chapter IV, we studied the activation of cycylopendienyl free oganolanthanide complexes on sulfur by which bis(guanidinate) lanthanides thiolate complexes {[(SiMe32NC(NCy)2]2LnSnBu}2 [Ln = Y (25), Dy (26), Nd(27)] were synthesized by the insertion of elemental sulfur into the Ln-C bonds of [(SiMe32NC(NCy)2]2LnR [Ln = Y (22), Dy (23), Nd (24)]. The complexe 25 were confirmed by X-ray diffraction crystal analysis.In Chapter V, in the course of synthesizing the bis(thienylmethyl-cyclopentadienyl) organolanthanide chloride complexes, two unexpected polynuclear lanthanide oxide complexes [(α-C4H3S)CH2C5H4Yb]6O9H6 (28) and [Sm4Cl8(THF)10](μ3222-O22 (29) were isolated。 The two complexes were confirmed by X-ray diffraction crystal analysis.

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