Research Article The Use of a Flexible Calix[4]arene Template to …downloads.hindawi.com/archive/2013/910172.pdf · 2019. 7. 31. · chemistry for complexing metallic cations [ ];

Hindawi Publishing CorporationJournal of CrystallographyVolume 2013 Article ID 910172 4 pageshttpdxdoiorg1011552013910172

Research ArticleThe Use of a Flexible Calix[4]arene Template to Stabilizea Cyclooctatetraindiyl Samarium-Potassium Complex

Geoffroy Guillemot12 Euro Solari1 Carlo Floriani1 and Thierry Prangeacute3

1 Institut de ChimieMoleculaire et Biologique Ecole Polytechnique Federale de Lausanne EPFL-BCH CH-1015 Lausanne Switzerland2 Institut Parisien de Chimie Moleculaire (UMR 7201-CNRS) Universite Pierre et Marie Curie Case Courrier 42 4 Place Jussieu75252 Paris Cedex 05 France

3 Laboratoire de Cristallographie et RMN Biologiques (UMR 8015-CNRS) Faculte de Pharmacie Universite Paris Descartes4 Avenue de lrsquoObservatoire 75006 Paris France

Correspondence should be addressed to Prange Thierry thierryprangeparisdescartesfr

Received 13 May 2013 Accepted 3 October 2013

Academic Editors M Akkurt J Jasinski and L MacGillivray

Copyright copy 2013 Guillemot Geoffroy et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

A sandwich compound of cyclooctatetraendiyl (COT)2minus samarium-potassium was synthesized and analyzed using a flexiblecalix[4]arene dianion This compound [p-tBu-calix[4]-(OMe)

2(O)2]arenediyl-samarium-(1205788-cyclooctatetraendiyl)-potassium

120583(tetrahydrofurane)3 is constructed as a linear sequence L-Sm-L1015840-K-L10158401015840 where L L1015840 and L10158401015840 are specific ligands with L = OO-

dimethyl-calix[4]arene2minus L1015840 = cyclo-octatetraendiyl and L10158401015840 = tetrahydrofurane templates

1 Introduction

For a long time the organometallic chemistry of lan-thanides (Ln) [1] has been dominated by the use ofpolycyclic hydrocarbons including the cyclopentadienylanion or the cyclooctatetraendiyl dianion as exemplifiedby the well-known lanthanocene [Cp

2Ln(III)]+ [2] and

[bis(cyclooctatetraenyl)Ln]minus complexes [3] In the last twodecades the organometallic and redox chemistry of thesehard metal ions has been extensively developed by theintroduction of amido thiolato and aryloxo ligands as wellas macrocyclic ligands such as octa-alkyl-porphyrinogensand calix[4]arenes [4 5] and a number of such examplesof COT2minus complexes have recently been published [6ndash10]Calixarenes are useful building blocks in supramolecularchemistry for complexing metallic cations [11] the useof calix[4]arene anions [12] brings significant peculiarities(i) the electron-rich environment provided by the oxygendonor atoms forms an ideal platform for developing theorganometallic and redox chemistry of lanthanides (ii) thequasi-planar arrangement of the four oxygen atoms result-ing from the cone conformation of the calix allows the

formation of ldquohalf-sandwichrdquo-type metallic complexes and(iii) it can accommodate up to 12 electrons to the metalcentre depending on the degree of 120587-donation Thereforeit came out that an interesting analogy can be drawnbetween the quasi-planar calix[4]arene polyanion and itselectronically similar cyclooctatetraendiyl dianion [13] inthe attempt to develop new scaffoldings in organometal-lic chemistry of Lanthanides In the present study wereport on the synthesis and crystallographic analysis of themixed cyclooctatetraendiyl samarium-potassium complex[119901-tBu-calix[4]-(OMe)

2(O)2]arenediyl samarium-(1205788-cyclo-

octatetraendiyl) potassium-120583(THF)3 stabilized by a flexible

calix[4]arene dianion template a compound that widensthe ability of unsymmetrical calix[4]arene as a useful andadaptable ligand in organometallic chemistry

2 Experimental

A solution of cyclooctatetraendiide dipotassium in THF[14] (88mL 0275M 242mmol) was added dropwise toa suspension of 2 (46 g 247mmol) [15] in THF (150mL)

2 Journal of Crystallography

at minus30∘C The reaction mixture was stirred overnight whileslowlywarming to room temperature leading to a suspensionof a white solid in a red solution The solid was filtered offthe solution was concentrated to ca 30mL and subsequentlykept at 3∘CThe orange precipitate was collected and dried invacuo Yield 21 g (34) of 3

Elemental analysis calcd () for C70H98KO8Sm (125704)

C 6688 H 786 found C 6649 H 760 Crystals suitable forXray crystallographywere grown at 3∘C from a THF solutionCrystal data Triclinic with parameters 119886 = 144610(2) A119887 = 154330(4) A 119888 = 65550(4) A 120572 = 10602(5)∘ 120573 =9862(5)

∘ 120574 = 10208(5)∘ and 119881 = 3387(1) A3 Crystalswere very sensitive to air and moisture They were fished outunder neutral atmosphere or under oil using a nylon loop andimmediately cryocooled in liquid nitrogen

Diffraction data were collected at 119879 = 143K on aMar345Image Plate detector (3∘ lt 2120579 lt 52∘) using the Mo K120572wavelength in the rotation method (180 steps of one degreeper frame) Diffraction data were processed with the HKLpackage [16] (22696 recorded reflections redundancy sim 2119877symm = 0028 completeness 92) No absorption correctionwas applied The final data set was reformatted for structuredetermination and refinement using the SHELXSL programs[17]

The structure was solved in centrosymmetric P-1 spacegroup by directmethodsDuring refinements a solvatedTHFmolecule was located highly disordered in the packing withhigh temperature factors Hydrogen atoms were kept at theirtheoretical places and refined as riding atoms to their bondedcarbon The four terbutyls of the calix[4]arene ligand knownto still rotate at low temperature were refined as restrainedgroups The final 119877 was 00514 (10196 observed data with119868 gt 2120590(119868)) and 1199081198772 = 01335 (calculated with the 11873unique squared reflections having 119868 gt 0) The coordinateswere deposited with the CCDC 12 Union Road CambridgeCB2 1EZ UK ref 880827

3 Discussion

The starting materials we devised in our previous work onlanthanides chemistry are displayed in Scheme 1 The useof the bis-O-methylated calix[4]arene allows tuning of themacrocyclic charge [12] to a value appropriate for entering thechemistry of lanthanides The reaction of LnCl

3(THF)

2with

the lithium or sodium salt of [119901-tBu-calix[4]-(OMe)2(OH)2]

[18] led to the formation of dimeric complexes2[119901-tBu-calix[4]-(OMe)

2(O)2-Ln(THF)]

2(120583-Cl)

2in which

the metal ions are bridged by two chloride anionsUnder dinitrogen the reduction of these lanthanidecomplexes (Ln = Pr Sm) by sodium naphthalenide hasbeen reported to carry out the four-electron reduction ofdinitrogen to a (120583

3-1205782 1205782 1205782-N

2) moiety supported

by a trinuclear complex and exhibiting a very highdegree of d(NndashN) bond elongation [15] The analogybetween C

8H8

2minus and [119901-tBu-calix[4]-(OMe)2(O)2]2minus

dianions led us to investigate the exchange reactionbetween [119901-tBu-calix[4]-(OMe)

2(O)2Sm(THF)]

2(120583-Cl)

2

and C8H8K2 This gave the mixed sandwich compound 3

Table 1 Calix[4]arene elliptical parametersa in 3 compared tocompounds 2 and 4a

Compound Da (A) Db (A) 120576 Reference3

Ring I 9937(5) 5467(5) 0835 mdashRing II 9854(5) 5396(5) 0836 mdash

2Ring I 9689(3) 5816(3) 0799 [15]

4Ring I 8861(4) 7752(4) 0484 idRing II 9668(4) 7441(4) 0638 idRing III 9503(4) 5694(4) 0800 id

aDa Db and 120576 are the long and short distances and eccentricity of the ellipsewhich encompasses the four para aromatic carbons of the ligand

The content of the asymmetric unit is shown in Figure 1The samarium-potassium complex adopts a linear structurewith a cylindrical shape of 15 A in length and forms asandwich scaffold with the samarium and potassium cationsinterspersedwith the three different ligands the calix[4]arenedianion on one side of the samarium (ligand L) the cyclooc-tatetraendiyl dianion (ligand L1015840) in between samarium andpotassium and three coordinating tetrahydrofuranes (THF)on the other side of the potassium (ligand L10158401015840)

Ligand L On one side a dissymmetric calix[4]arene is usedwith alternate protected (methoxy) and free (oxygen anion)polar atoms It interacts with the samarium cation at shortdistance with only two oxygens forcing the skeleton toassume a very constrained elliptical conformation with theSm1-O(2) and Sm1-O(4) distances particularly long (119889

2=

2694(3) A and 1198894= 2795(4) A) compared to the two

others Sm1-O(1) and Sm1-O(3) (1198891= 2189(3) A and 119889

3=

2186(3) A) Table 1 reports the macrocycle ring eccentricitycompared with two other nonsymmetric calix[4]arene com-pounds the parent dimer (L-SmCl)

22 and the correspond-

ing (L3Sm2N2) complex 4 (Scheme 1) all using the same

flexible ligand The calix[4] ligand in the asymmetric unitof 3 has a much higher 120576 value than those observed in thestructures of 2 and 4 [15] It is interesting to note that in thedinitrogen complex 4 the three calix[4]arene ligands adaptthemselves to the central Sm

2-N2cluster through their high

plasticity This is evidenced by the different values of each 120576parameter (Table 1)

1198711015840-The Central Ligand The cyclooctatetraindiyl dianion

adopts a perfect planar configuration due to its aromaticityand supports a full coordination with both the potassiumand samarium cations located on opposite sides Withinthe dianion the average bond distance is ⟨119889⟩ = 1413 Awith sd sim 003 A while the mean angle is around the idealvalue of 31205874 with sd sim10∘ These values correspond to anearly perfect unconstrained octagon The two samariumand potassium cations at 4552(2) A from each other areperpendicular to the center of the ring with individualdistances = 209 and 246 A from the COT plane respectivelyThese distances are relevant to a similar partition of charges

Journal of Crystallography 3

L-Sm

Cl

ClSm-L L-Sm-

N N

Sm Sm

Sm

LL

L

23

4

O

O

L998400-K2

THF (==

L998400998400)

-K-L998400998400

L =L998400= =Ominus

Ominus

Scheme 1 Preparation of the samarium-potassium complex 3 from calix[4]arene (OMe)2(OH)

2samarium chloride 2

Sm

K

O1O3

O2 O4

Figure 1 Overall view of the samarium-potassium sandwich struc-ture of 3The solvated THFmolecule and hydrogens are omitted forclarity The three ligands are given in different colors L is in blackCOT is in orange and the potassium THFs (ligand L10158401015840) are in green

on both sides according to the respective ionic radii of Sm3+and K+ (sim 11 and 133 A)

11987110158401015840-Potassium TemplateThe potassium ion completes on the

other side its coordination sphere with three molecules ofTHF

Solvation In addition to the title molecule in the asymmetricunit there is an additional solvated THF molecule (notshown in Figure 1) with very large thermal parameters Thismolecule lies in the vicinity of the L10158401015840 ligand

4 Conclusion

The present structure of a mixed rare earth-potassium com-plex of cyclooctatetraindiyl dianion together with the twoother crystal structures of 2 and 4 illustrates and generalizeshow the plasticity of a calix[4]arene dianion with alternateMeOO-polar groups can be used in the building of stablescaffolds in reactive organometallic systems of lanthanides

References

[1] W J Evans ldquoThe importance of questioning scientific assump-tions some lessons from f element chemistryrdquo Inorganic Chem-istry vol 46 no 9 pp 3435ndash3449 2007

[2] C-T Qian and C-J Zhu ldquoSynthesis structure and reactivity oflanthanocene complexesrdquo Chinese Journal of Chemistry vol 20no 6 pp 519ndash535 2002

[3] U Kilimann and F T Edelmann ldquoNeue cyclooctatetraenyl-lanthanid(III)-komplexerdquo Journal of Organometallic Chemistryvol 444 no 1-2 pp C15ndashC17 1993

[4] M F Lappert W J Evans and D M P Mingos ldquoRecentadvances in the organometallic chemistry of the group 3 andlanthanoid elementsrdquo Journal of Organometallic Chemistry vol647 no 1-2 2002

[5] F T Edelmann ldquoLanthanides and actinides annual surveyof their organometallic chemistry covering the year 2008rdquoCoordination Chemistry Reviews vol 255 no 15-16 pp 1834ndash1920 2011

[6] J Xia Z Jin and W Chen ldquoSynthesis and crystal structure of anew lanthanide cyclooctatetraene complex (1205788-C

8H8)Er(120583-1205788-

C8H8)K(120583-1205788-C

8H8)Er(120583-1205788-C

8H8) K(THF)

4rdquo Journal of the

Chemical Society Chemical Communications no 17 pp 1214ndash1215 1991

[7] U Kilimann M Schafer R Herbst-Irmer and F T EdelmannldquoCyclooctatetraenyl-komplexe der fruhen ubergangsmetalleund lanthanoide IV Strukturchemie des anionisichensandwich-komplexes [Ce(COT)

2]minusrdquo Journal of Organometallic

Chemistry vol 469 no 1 pp C15ndashC18 1994

[8] J Xia X Zhuang Z Jin and W Chen ldquoSynthesis and crystalstructure of [(C

8H8)3(C6H5CH2C5H4)Nd2K(THF)

3]rdquo Polyhe-

dron vol 15 no 19 pp 3399ndash3403 1996


[9] J Jin Z Jin G Wei and W Chen ldquo(1205832-1205788 1205788-cyclo-octatetraenyl)-(1205788-cyclo-octatetraenyl)-tris(tetrahydrofuran-O)-samarium-sodiumrdquo Chinese Journal of Inorganic Chemistryvol 9 p 326 1993

[10] W J Evans J L Shreeve and J W Ziller ldquoSynthesis andstructure of inverse cyclooctatetraenyl sandwich complexes ofEuropium(II) [(C

5Me5)(THF)

2Eu]2(120583-C8H8and [(THF)

3K(120583-

C8H8)]2Eurdquo Polyhedron vol 14 no 20-21 pp 2945ndash2951 1995

[11] J L Atwood GW Orr R K Juneja S G Bott and F HamadaldquoSupramolecular assemblies based on calixarenesrdquo Pure andApplied Chemistry vol 65 pp 1471ndash1476 1993

[12] C Floriani and R Floriani-MoroMetal Reactivity on Oxo Sur-faces Modeled by Calix[4]arenes Kluwer Academic PublishersDordrecht The Nederlands 2002

[13] T Sommerfeld ldquoA fresh look at aromatic dianionsrdquo Journal ofthe American Chemical Society vol 124 no 6 pp 1119ndash11242002

[14] T J Katz ldquoThe cyclooctatetraenyl dianionrdquo Journal of theAmerican Chemical Society vol 82 pp 3784ndash3785 1960

[15] G Guillemot B Castellano T Prange E Solari andC FlorianildquoUse of calix[4]arenes in the redox chemistry of lanthanides thereduction of dinitrogen by a calix[4]arene-samarium complexrdquoInorganic Chemistry vol 46 no 13 pp 5152ndash5154 2007

[16] Z Otwinowski and W Minor ldquoProcessing of X-ray diffractiondata collected in oscillationmoderdquoMethods in Enzymology vol276 pp 307ndash326 1997

[17] G M Sheldrick ldquoA short history of SHELXrdquo Acta Crystallo-graphica A vol 64 no 1 pp 112ndash122 2008

[18] G Guillemot E Solari C Rizzoli and C Floriani ldquoAlkaliand alkaline-earth-metalated forms of calix[4]arenes synthonsin the synthesis of transition metal complexesrdquo ChemistrymdashAEuropean Journal vol 8 no 9 pp 2072ndash2080 2002

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at minus30∘C The reaction mixture was stirred overnight whileslowlywarming to room temperature leading to a suspensionof a white solid in a red solution The solid was filtered offthe solution was concentrated to ca 30mL and subsequentlykept at 3∘CThe orange precipitate was collected and dried invacuo Yield 21 g (34) of 3

Elemental analysis calcd () for C70H98KO8Sm (125704)

C 6688 H 786 found C 6649 H 760 Crystals suitable forXray crystallographywere grown at 3∘C from a THF solutionCrystal data Triclinic with parameters 119886 = 144610(2) A119887 = 154330(4) A 119888 = 65550(4) A 120572 = 10602(5)∘ 120573 =9862(5)

∘ 120574 = 10208(5)∘ and 119881 = 3387(1) A3 Crystalswere very sensitive to air and moisture They were fished outunder neutral atmosphere or under oil using a nylon loop andimmediately cryocooled in liquid nitrogen

Diffraction data were collected at 119879 = 143K on aMar345Image Plate detector (3∘ lt 2120579 lt 52∘) using the Mo K120572wavelength in the rotation method (180 steps of one degreeper frame) Diffraction data were processed with the HKLpackage [16] (22696 recorded reflections redundancy sim 2119877symm = 0028 completeness 92) No absorption correctionwas applied The final data set was reformatted for structuredetermination and refinement using the SHELXSL programs[17]

The structure was solved in centrosymmetric P-1 spacegroup by directmethodsDuring refinements a solvatedTHFmolecule was located highly disordered in the packing withhigh temperature factors Hydrogen atoms were kept at theirtheoretical places and refined as riding atoms to their bondedcarbon The four terbutyls of the calix[4]arene ligand knownto still rotate at low temperature were refined as restrainedgroups The final 119877 was 00514 (10196 observed data with119868 gt 2120590(119868)) and 1199081198772 = 01335 (calculated with the 11873unique squared reflections having 119868 gt 0) The coordinateswere deposited with the CCDC 12 Union Road CambridgeCB2 1EZ UK ref 880827

3 Discussion

The starting materials we devised in our previous work onlanthanides chemistry are displayed in Scheme 1 The useof the bis-O-methylated calix[4]arene allows tuning of themacrocyclic charge [12] to a value appropriate for entering thechemistry of lanthanides The reaction of LnCl

3(THF)

2with

the lithium or sodium salt of [119901-tBu-calix[4]-(OMe)2(OH)2]

[18] led to the formation of dimeric complexes2[119901-tBu-calix[4]-(OMe)

2(O)2-Ln(THF)]

2(120583-Cl)

2in which

the metal ions are bridged by two chloride anionsUnder dinitrogen the reduction of these lanthanidecomplexes (Ln = Pr Sm) by sodium naphthalenide hasbeen reported to carry out the four-electron reduction ofdinitrogen to a (120583

3-1205782 1205782 1205782-N

2) moiety supported

by a trinuclear complex and exhibiting a very highdegree of d(NndashN) bond elongation [15] The analogybetween C

8H8

2minus and [119901-tBu-calix[4]-(OMe)2(O)2]2minus

dianions led us to investigate the exchange reactionbetween [119901-tBu-calix[4]-(OMe)

2(O)2Sm(THF)]

2(120583-Cl)

2

and C8H8K2 This gave the mixed sandwich compound 3

Table 1 Calix[4]arene elliptical parametersa in 3 compared tocompounds 2 and 4a

Compound Da (A) Db (A) 120576 Reference3

Ring I 9937(5) 5467(5) 0835 mdashRing II 9854(5) 5396(5) 0836 mdash

2Ring I 9689(3) 5816(3) 0799 [15]

4Ring I 8861(4) 7752(4) 0484 idRing II 9668(4) 7441(4) 0638 idRing III 9503(4) 5694(4) 0800 id

aDa Db and 120576 are the long and short distances and eccentricity of the ellipsewhich encompasses the four para aromatic carbons of the ligand

The content of the asymmetric unit is shown in Figure 1The samarium-potassium complex adopts a linear structurewith a cylindrical shape of 15 A in length and forms asandwich scaffold with the samarium and potassium cationsinterspersedwith the three different ligands the calix[4]arenedianion on one side of the samarium (ligand L) the cyclooc-tatetraendiyl dianion (ligand L1015840) in between samarium andpotassium and three coordinating tetrahydrofuranes (THF)on the other side of the potassium (ligand L10158401015840)

Ligand L On one side a dissymmetric calix[4]arene is usedwith alternate protected (methoxy) and free (oxygen anion)polar atoms It interacts with the samarium cation at shortdistance with only two oxygens forcing the skeleton toassume a very constrained elliptical conformation with theSm1-O(2) and Sm1-O(4) distances particularly long (119889

2=

2694(3) A and 1198894= 2795(4) A) compared to the two

others Sm1-O(1) and Sm1-O(3) (1198891= 2189(3) A and 119889

3=

2186(3) A) Table 1 reports the macrocycle ring eccentricitycompared with two other nonsymmetric calix[4]arene com-pounds the parent dimer (L-SmCl)

22 and the correspond-

ing (L3Sm2N2) complex 4 (Scheme 1) all using the same

flexible ligand The calix[4] ligand in the asymmetric unitof 3 has a much higher 120576 value than those observed in thestructures of 2 and 4 [15] It is interesting to note that in thedinitrogen complex 4 the three calix[4]arene ligands adaptthemselves to the central Sm

2-N2cluster through their high

plasticity This is evidenced by the different values of each 120576parameter (Table 1)

1198711015840-The Central Ligand The cyclooctatetraindiyl dianion

adopts a perfect planar configuration due to its aromaticityand supports a full coordination with both the potassiumand samarium cations located on opposite sides Withinthe dianion the average bond distance is ⟨119889⟩ = 1413 Awith sd sim 003 A while the mean angle is around the idealvalue of 31205874 with sd sim10∘ These values correspond to anearly perfect unconstrained octagon The two samariumand potassium cations at 4552(2) A from each other areperpendicular to the center of the ring with individualdistances = 209 and 246 A from the COT plane respectivelyThese distances are relevant to a similar partition of charges


L-Sm

Cl

ClSm-L L-Sm-

N N

Sm Sm

Sm

LL

L

23

4

O

O

L998400-K2

THF (==

L998400998400)

-K-L998400998400

L =L998400= =Ominus

Ominus



Sm

K

O1O3

O2 O4






4 Conclusion


References







8H8)Er(120583-1205788-

C8H8)K(120583-1205788-C

8H8)Er(120583-1205788-C

8H8) K(THF)








3]rdquo Polyhe-





5Me5)(THF)

2Eu]2(120583-C8H8and [(THF)

3K(120583-

















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




L-Sm

Cl

ClSm-L L-Sm-

N N

Sm Sm

Sm

LL

L

23

4

O

O

L998400-K2

THF (==

L998400998400)

-K-L998400998400

L =L998400= =Ominus

Ominus



Sm

K

O1O3

O2 O4






4 Conclusion


References







8H8)Er(120583-1205788-

C8H8)K(120583-1205788-C

8H8)Er(120583-1205788-C

8H8) K(THF)








3]rdquo Polyhe-





5Me5)(THF)

2Eu]2(120583-C8H8and [(THF)

3K(120583-

















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials






5Me5)(THF)

2Eu]2(120583-C8H8and [(THF)

3K(120583-

















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials










CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



Documents

Research Article The Use of a Flexible Calix[4]arene Template to …downloads.hindawi.com/archive/2013/910172.pdf · 2019. 7. 31. · chemistry for complexing metallic cations [ ];