Bent vs Linear Metallocenes Involving C5Me5 vs C8H8 Ligands: Synthesis, Structure, and Reactivity of the Triple-Decked (C5Me5)(THF)
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- 作者：William J. Evans ; Robert D. Clark ; Mohammad A. Ansari ; and Joseph W. Ziller
- 刊名：Journal of the American Chemical Society
- 出版年：1998
- 出版时间：September 23, 1998
- 年：1998
- 卷：120
- 期：37
- 页码：9555 - 9563
- 全文大小：165K
- 年卷期：v.120,no.37(September 23, 1998)
- ISSN：1520-5126
文摘
A new series of bimetallic triple-decked organometallic sandwich complexes involving Sm(II) canbe prepared by reacting [(C5Me4R)Sm(
-I)(THF)2]2 with 1 equiv of K2C8H8 in toluene to form [(C5Me4R)Sm(THF)]2(-
8:8-C8H8) (R = Me, 1; R = Et, 2). The diglyme ([MeOCH2CH2]2O) adduct of 1, {[(C5Me5)Sm(diglyme)]2(-8:8-C8H8)}(THF)2 (3) crystallizes from THF with a bridging (C8H8)2- dianion sandwichedbetween two [(C5Me5)Sm(diglyme)]+ cations with a 137.6
(C5Me5 ring centroid)-Sm-(C8H8 ring centroid)angle. This bent triple-decked metallocene has 2.91(2) Å Sm-C(C5Me5) and 2.96(5) Å Sm-C(C8H8) averagedistances. 1 and 2 can be desolvated at 30-50 C under high vacuum over several hours to yield [(C5Me4R)Sm]2(-8:8-C8H8) (R = Me, 4; R = Et, 5). It was of interest to determine if 4 and 5 had triple-deckedmetallocene structures with three parallel rings since previously characterized bis(cyclooctatetraenyl) lanthanideand actinide complexes such as uranocene, (C8H8)2U, and [(C8H8)2Ce]- have parallel rings whereas (C5Me5)2Sm is bent. Complex 4 is found to crystallize from toluene with a structure that retains the bent geometry of3 with 149.3 and 148.9 (C5Me5 ring centroid)-Sm-(C8H8 ring centroid) angles. 5 crystallizes from toluenewith a similar bent triple-decked metallocene structure with 157.6 (C5Me5 ring centroid)-Sm-(C8H8 ringcentroid) angles. The ethyl groups in 5 are oriented toward the metal center with 3.40 Å Sm···C(CH2CH3)distances. Complexes 1 and 2 each do two-electron reductions of 1,3,5,7-C8H8 to form (C5Me4R)Sm(C8H8)(THF); 4 and 5 react similarly with 1,3,5,7-C8H8 to form (C5Me4R)Sm(C8H8). A two-electron reduction ofC5Me5Cl by 1 generates (C5Me5)Sm(C8H8)(THF) and (C5Me5)2SmCl(THF), a product in which C5Me5Cl hasbeen added to a single (C5Me5)Sm(THF) unit in 1.
-I)(THF)2]2 with 1 equiv of K2C8H8 in toluene to form [(C5Me4R)Sm(THF)]2(-8:8-C8H8) (R = Me, 1; R = Et, 2). The diglyme ([MeOCH2CH2]2O) adduct of 1, {[(C5Me5)Sm(diglyme)]2(-8:8-C8H8)}(THF)2 (3) crystallizes from THF with a bridging (C8H8)2- dianion sandwichedbetween two [(C5Me5)Sm(diglyme)]+ cations with a 137.6 (C5Me5 ring centroid)-Sm-(C8H8 ring centroid)angle. This bent triple-decked metallocene has 2.91(2) Å Sm-C(C5Me5) and 2.96(5) Å Sm-C(C8H8) averagedistances. 1 and 2 can be desolvated at 30-50 C under high vacuum over several hours to yield [(C5Me4R)Sm]2(-8:8-C8H8) (R = Me, 4; R = Et, 5). It was of interest to determine if 4 and 5 had triple-deckedmetallocene structures with three parallel rings since previously characterized bis(cyclooctatetraenyl) lanthanideand actinide complexes such as uranocene, (C8H8)2U, and [(C8H8)2Ce]- have parallel rings whereas (C5Me5)2Sm is bent. Complex 4 is found to crystallize from toluene with a structure that retains the bent geometry of3 with 149.3 and 148.9 (C5Me5 ring centroid)-Sm-(C8H8 ring centroid) angles. 5 crystallizes from toluenewith a similar bent triple-decked metallocene structure with 157.6 (C5Me5 ring centroid)-Sm-(C8H8 ringcentroid) angles. The ethyl groups in 5 are oriented toward the metal center with 3.40 Å Sm···C(CH2CH3)distances. Complexes 1 and 2 each do two-electron reductions of 1,3,5,7-C8H8 to form (C5Me4R)Sm(C8H8)(THF); 4 and 5 react similarly with 1,3,5,7-C8H8 to form (C5Me4R)Sm(C8H8). A two-electron reduction ofC5Me5Cl by 1 generates (C5Me5)Sm(C8H8)(THF) and (C5Me5)2SmCl(THF), a product in which C5Me5Cl hasbeen added to a single (C5Me5)Sm(THF) unit in 1.