In this study we present a(re-)investigation into cyclodimethylsiloxanes in relation to silyl-ether bonding towards alkali metal ions.We demonstrate that all(non-radioactive)alkali metal ions can be incorporated into ...In this study we present a(re-)investigation into cyclodimethylsiloxanes in relation to silyl-ether bonding towards alkali metal ions.We demonstrate that all(non-radioactive)alkali metal ions can be incorporated into D_(n) cyclosiloxane frameworks(D=(SiMe_(2)O),n=5–8),employing appropriate cation–anion combinations.Starting with the Li^(+)cation we were able to observe the coordination of D_(5) with Li^(+)based on a suitable X-ray structure after reacting D_(5) with LiI and GaI_(3).Due to template effects,the dinuclear coordination compound[Li2(D_(5))(D_(6))(GaI_(4))_(2)](1)was obtained.The direct reaction of D_(6) with LiI and GaI_(3) yields[Li(D_(6))GaI_(4)](2)in quantitative yield.Na^(+)ions could be trapped in D_(6) and D_(7) ligand moieties after the conversion of NaI,GaI_(3),and the respective siloxane.The molecular structure of[Na(D_(6))GaI_(4)](3)reveals a six-fold coordinated Na^(+)ion,which is located on top of the siloxane D_(6).In the case of[Na(D_(7))(DCM)GaI_(4)](4),the larger ligand D_(7) provides 15-crown-5-like geometry in which the sodium ion is coordinated by the ligand in a coplanar fashion and further saturated by the solvent DCM(DCM=dichloromethane).The K^(+)ion was bound within the D_(7) ligand in a similar manner and[K(D_(7))(DCM)GaI_(4)](5)could be characterized.Due to the resemblance of NH_(4)^(+)to K^(+),this cation was also employed for complex formation.Counterintuitively,we were able to synthesize and characterize the first ever non-metal-cyclosiloxane coordination compound.After the conversion of D_(6) with NH_(4)I and GaI_(3),the compound[NH_(4)(D_(7))][Ga_(2)I_(7)](6)was obtained.The ammonium cation favors D_(7) coordination over D_(6),and the willing formation of hydrogen bonding in such a siloxane moiety was realized.As these compounds could be obtained,we also tested the limits of silyl-ether bonding.Therefore,we reacted D_(8) with in situ generated Rb[GaI_(4)]and Cs[GaI_(4)].In the case of Rb^(+),we could cumbersomely characterize[Rb(D_(8))(DCM)GaI_(4)](7)via an X-ray structure,as well as by means of mass spectrometry,but the compound starts decomposing readily in solution.The reaction with the Cs^(+)salt failed.To obtain meaningful spectroscopic data from a Rb^(+)compound and to somehow obtain a Cs^(+)complex,we employed the weakly coordinating anion[Al_(F)]^(−)(Al_(F)^(−)=[Al{OC(CF_(3))_(3)}_(4)]^(−)).The conversion of M[Al_(F)]then yielded 11[M(D_(8))AL_(F)](M=Rb:8;M=Cs^(+):9)in the solid state.Both compounds 8 and 9 were fully characterized.Finally,we aimed at synthesizing 2:1 complexes of such siloxanes.The reactions of excess D_(5) with K[Al_(F)]and D_(6) with Cs[Al_(F)]turned out to be expedient and,in the forms of[K(D_(5))_(2)][Al_(F)](10)and[Cs(D_(6))_(2)][Al_(F)](12),the first ever sandwich-type complexes observed bearing a cyclosiloxane ligand were characterized.展开更多
基金financially supported by the Deutsche Forschungsgemeinschaft(DFG).
文摘In this study we present a(re-)investigation into cyclodimethylsiloxanes in relation to silyl-ether bonding towards alkali metal ions.We demonstrate that all(non-radioactive)alkali metal ions can be incorporated into D_(n) cyclosiloxane frameworks(D=(SiMe_(2)O),n=5–8),employing appropriate cation–anion combinations.Starting with the Li^(+)cation we were able to observe the coordination of D_(5) with Li^(+)based on a suitable X-ray structure after reacting D_(5) with LiI and GaI_(3).Due to template effects,the dinuclear coordination compound[Li2(D_(5))(D_(6))(GaI_(4))_(2)](1)was obtained.The direct reaction of D_(6) with LiI and GaI_(3) yields[Li(D_(6))GaI_(4)](2)in quantitative yield.Na^(+)ions could be trapped in D_(6) and D_(7) ligand moieties after the conversion of NaI,GaI_(3),and the respective siloxane.The molecular structure of[Na(D_(6))GaI_(4)](3)reveals a six-fold coordinated Na^(+)ion,which is located on top of the siloxane D_(6).In the case of[Na(D_(7))(DCM)GaI_(4)](4),the larger ligand D_(7) provides 15-crown-5-like geometry in which the sodium ion is coordinated by the ligand in a coplanar fashion and further saturated by the solvent DCM(DCM=dichloromethane).The K^(+)ion was bound within the D_(7) ligand in a similar manner and[K(D_(7))(DCM)GaI_(4)](5)could be characterized.Due to the resemblance of NH_(4)^(+)to K^(+),this cation was also employed for complex formation.Counterintuitively,we were able to synthesize and characterize the first ever non-metal-cyclosiloxane coordination compound.After the conversion of D_(6) with NH_(4)I and GaI_(3),the compound[NH_(4)(D_(7))][Ga_(2)I_(7)](6)was obtained.The ammonium cation favors D_(7) coordination over D_(6),and the willing formation of hydrogen bonding in such a siloxane moiety was realized.As these compounds could be obtained,we also tested the limits of silyl-ether bonding.Therefore,we reacted D_(8) with in situ generated Rb[GaI_(4)]and Cs[GaI_(4)].In the case of Rb^(+),we could cumbersomely characterize[Rb(D_(8))(DCM)GaI_(4)](7)via an X-ray structure,as well as by means of mass spectrometry,but the compound starts decomposing readily in solution.The reaction with the Cs^(+)salt failed.To obtain meaningful spectroscopic data from a Rb^(+)compound and to somehow obtain a Cs^(+)complex,we employed the weakly coordinating anion[Al_(F)]^(−)(Al_(F)^(−)=[Al{OC(CF_(3))_(3)}_(4)]^(−)).The conversion of M[Al_(F)]then yielded 11[M(D_(8))AL_(F)](M=Rb:8;M=Cs^(+):9)in the solid state.Both compounds 8 and 9 were fully characterized.Finally,we aimed at synthesizing 2:1 complexes of such siloxanes.The reactions of excess D_(5) with K[Al_(F)]and D_(6) with Cs[Al_(F)]turned out to be expedient and,in the forms of[K(D_(5))_(2)][Al_(F)](10)and[Cs(D_(6))_(2)][Al_(F)](12),the first ever sandwich-type complexes observed bearing a cyclosiloxane ligand were characterized.
