f-Element Disiloxanediolates: Novel Si−O-based Inorganic Heterocycles

Lorenz, Volker; Fischer, Axel; Jacob, K.; Brüser, Wolfgang; Edelmann, Frank T.

doi:10.1002/1521-3765(20010216)7:4<848::aid-chem848>3.0.co;2-r

Cited by 38 publications

(17 citation statements)

References 70 publications

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“…Whereas most reactions of tetraphenyldisiloxanediol with the lanthanide silylamide reagents as described above proceeded in a clear and straightforward manner, a completely different picture was seen when anhydrous lanthanide trihalides were treated with Ph 2 Si(OLi)OSiPh 2 (OLi) ( 4 ) 9b. Some products resulting from these reactions still remain to be fully characterized, but it appears that they are all different from that shown in Scheme .…”

Section: Heterobimetallic Siloxanediolates Of the Lanthanidesmentioning

confidence: 98%

“…An interesting example, in which retention of lithium halide led to a self‐assembled polymeric structure is the product obtained from the reaction of anhydrous NdBr 3 with three equivalents of 4 in THF solution according to Scheme . Extraction of the crude product with diethyl ether afforded the heterobimetallic neodymium disiloxanediolate 24 as a blue crystalline solid 9b.…”

Section: Heterobimetallic Siloxanediolates Of the Lanthanidesmentioning

confidence: 99%

“…In contrast to the molecular structure of 23 there are four tricoordinate disiloxanediolate oxygen atoms, whereas two are tetracoordinate. In 24 a polymeric superstructure results from retention of lithium bromide, which connects these monomeric units to give a linear chain polymer 9b.…”

Section: Heterobimetallic Siloxanediolates Of the Lanthanidesmentioning

confidence: 99%

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Disiloxanediolates and Metallasilsesquioxanes of the Rare Earth Elements

Lorenz

Edelmann

Gießmann

et al. 2010

Zeitschrift anorg allge chemie

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This research report summarizes recent results in the chemistry of lanthanide disiloxanediolates and metallasilsesquioxanes. Both classes of compound can be regarded as realistic model compounds for silica-supported lanthanide catalysts. Heterobimetallic siloxanediolates of the lanthanidesThe chemistry of metallasiloxanes derived from silanediols, disiloxanediols and related Si-OH species continues to be an area of vigorous research activities [1][2][3][4][5][6][7] Lanthanide(III) disiloxanediolates a) Lanthanide(III) mono(disiloxanediolates)By now, the chemistry of lanthanide bis(disiloxanediolates) is well established, and some lanthanide tris(disiloxanediolates) have also been prepared and structurally characterized (vide infra) [9]. Only the synthesis of mono-substituted rare earth metal complexes derived from difunctional siloxanediolate ligands had not been achieved until recently. Thus far only one compound of this type has been synthesized and structurally 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 Scheme 1An X-ray study confirmed the presence of the first mono(trisiloxanediolate) complex of a lanthanide element. The molecule contains a puckered eight-membered for hafnium and uranium [6,7,9]. In these cases, however, the trisiloxanediolate ligand is formed by ring-enlargement reactions starting from disiloxanediolate precursors. A prominent structural feature of compound 5 is the presence of a so-called "ate" complex resulting from retention of lithium chloride. "Ate" complexes are a common phenomenon in organolanthanide chemistry. Their formation involves retention of alkali halides formed during the course of a reaction, thereby reflecting the strong tendency of the large lanthanide ions to achieve high coordination numbers [11]. In compound 5 the situation is such that a complex of the type "[Ph 2 Si(OSiPh 2 O) 2 ]YbCl" is sterically highly unsaturated (coordination number 3 at Yb). In this case stabilitzation is achieved not only by coordination of one THF ligand but also through "ate" complex formation with retention of two equivalents of LiCl. One lithium chloride is connected to the central ytterbium via two bridging chloride ligands. The second LiCl is coordinated in a rather peculiar way by additional coordination of a siloxide oxygen atom to Li. In both cases, the coordination sphere around lithium is supplemented by two THF ligands (Fig. 1) [10]. Page 4 of 53Wiley-VCH ZAAC 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 Accordingly these complexes have been termed "metallacrown" derivatives of scandium and yttrium [9]. In contrast, large Ln 3+ ions such as Pr 3+ , Nd 3+ or Sm 3+ do no fit into the center of the twelve-membered ...

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Section: Heterobimetallic Siloxanediolates Of the Lanthanidesmentioning

confidence: 98%

Section: Heterobimetallic Siloxanediolates Of the Lanthanidesmentioning

confidence: 99%

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Disiloxanediolates and Metallasilsesquioxanes of the Rare Earth Elements

Lorenz

Edelmann

Gießmann

et al. 2010

Zeitschrift anorg allge chemie

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“…[12][13][14][15][16][17][18][19][20] Our group recently synthesized a sterically overloaded silanediol of formula (CH 2 SiR 2 OH) 2 (1),…”

Section: Yttrium and Lanthanum Disiloxidesmentioning

confidence: 99%

“…[8][9][10][11][12][13] In particular work by the Edelmann group has resulted in significant advancements in the synthesis of rare earth metal complexes supported by the tetraphenyldisiloxanediolate dianion, [(Ph 2 SiO) 2 O] 2-. [12][13][14][15][16][17][18][19][20] Our group recently synthesized a sterically overloaded silanediol of formula (CH 2 SiR 2 OH) 2 (1),…”

Section: Brianmentioning

confidence: 99%

Synthesis and structure of sterically overloaded tetra-coordinated yttrium and lanthanum disiloxides

McNerney

Mummadi

Hung‐Low

et al. 2016

Inorganic Chemistry Communications

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Synthesis and structure of sterically overloaded tetra-coordinated yttrium and lanthanum disiloxides, Inorganic Chemistry Communications (2016Communications ( ), doi: 10.1016Communications ( /j.inoche.2016 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT Synthesis and Structure of Sterically Overloaded Tetra-coordinated Yttrium and Lanthanum DisiloxidesBrian McNerney [a] , Suresh Mummadi [a] , Fernando Hung-Low [a] , David B. Cordes [b] , Daniel K.Unruh [a] , Clemens Krempner* [a] [a] Department of Chemistry & Biochemistry, Texas Tech University, Box 1061, Lubbock, Texas, 79409-1061 In the past half century, rare earth metal siloxides [1] have gained some popularity primarily due to their potential as homogeneous catalysts in polymerization catalysis [2][3][4] , as precursors for the formation of metal oxides and silicates [5][6][7] , and as models for silica-supported lanthanide metal heterogeneous catalysts. [8][9][10][11][12][13] In particular work by the Edelmann group has resulted in significant advancements in the synthesis of rare earth metal complexes supported by the. [12][13][14][15][16][17][18][19][20] Our group recently synthesized a sterically overloaded silanediol of formula (CH 2 SiR 2 OH) 2 (1),where R = Si(SiMe 3 ) 2 Me, and demonstrated that its deprotonated form serves as a dianionic chelating spectator ligand for aluminum alkyls, hydroxides and alkoxides. [21] One of these complexes, a monomeric aluminum isopropoxide (Scheme 1) proved to be one of the most active MPV A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPTcatalyst for the reduction of ketones and aldehydes reported so far. [22] Key to its high activty was its monomeric nature enforced by the bulkiness of the supporting disiloxide ligand. Based on these results, we reasoned that sterically overloaded disilanol 1 might be the ideal ligand for the synthesis of heteroleptic and salt-and adduct-free rare earth siloxide complexes, the latter potentially useful as Lewis acid catalysts.Scheme 1. Synthesis of sterically overloaded aluminum disiloxides.We first attempted to prepare the heteroleptic yttrium and lanthanum disiloxides of formula [(CH 2 R 2 SiO) 2 MN(SiMe 3 ) 2 ] (M = Ln, Y; R = SiMe(SiMe 3 ) 2 ) (2), respectively, as illustrated in Scheme 2. Initially, one equivalent of disilanol 1 was reacted with one equivalent of La(N(SiMe 3 ) 2 ) 3 in toluene as solvent. The reaction, however, did not give 2 but instead yielded the spirocyclic lanthanum disiloxide 3 as the main product irrespective whether toluene, THF or hexanes were used as solvents. Best yield...

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Lanthanides: Siloxides

Krempner

McNerney

2012

Encyclopedia of Inorganic and Bioinorganic Chemistry

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The chemistry of rare earth siloxides, also referred to as rare earth silanolates or silyloxides, is reviewed. After a brief discussion of the electronic and steric properties of various siloxide ligands, the synthetic and structural aspects of divalent, trivalent, and tetravalent rare earth siloxides are presented along with selected reactivity studies. The main focus, however, is on the chemistry of trivalent rare earth siloxides with special emphasis given to the steric and electronic influence of the siloxide ligand on the structure, stability, and reactivity on the supported rare earth metal. Applications of some heteroleptic rare earth siloxides as homogeneous catalysts in the polymerization of isoprene and hydrosilylation of olefins are included and briefly discussed.

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f-Element Disiloxanediolates: Novel Si−O-based Inorganic Heterocycles

Cited by 38 publications

References 70 publications

Disiloxanediolates and Metallasilsesquioxanes of the Rare Earth Elements

Disiloxanediolates and Metallasilsesquioxanes of the Rare Earth Elements

Synthesis and structure of sterically overloaded tetra-coordinated yttrium and lanthanum disiloxides

Lanthanides: Siloxides

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