Ein größenselektiver Anionenaustausch ist möglich mit dem hier dargestellten Polyrotaxan‐Verbundnetz, dessen Sekundär‐Baueinheiten sich aus je sechs Kupferionen und Pseudorotaxaneinheiten ...zusammensetzen. Zur Synthese wurde eine neue Strategie für die Herstellung modular aufgebauter poröser Feststoffe eingeführt, bei der große, starre, ineinander greifende Übermoleküle als Primär‐ und Sekundär‐Baueinheiten dienen.
The chemistry of early transition metal porphyrin complexes, especially, that of the second- and third-row metal complexes has not been developed much due in part to their high oxophilicity. The ...authors have been interested in exploring zirconium and hafnium porphyrin complexes because they may show a rich organometallic chemistry as zirconocene derivatives do. The key entry to the organometallic zirconium porphyrin complexes would be Zr(porphyrin)Clsub 2, analogous to ZrCpsub 2Clsub 2. The dichloride complex may be converted to organometallic sigma-complexes such as dialkyl complexes by the reactions with alkyllithium or Grignard reagents. It may also form organometallic tau-complexes by replacing the two chlorides with a cyclooctatetraenyl dianion or a dicarbollide dianion. Indeed, the authors have succeeded in preparing Zr(por)Clsub 2 (por = OEP, TPP) and their organometallic derivatives Zr(TPP)Mesub 2 and Zr(OEP)(etasup 5-Csub 2Bsub 9Hsub 11). They have presented the preliminary results on their syntheses and characterization by spectroscopy but have been unable to grow X-ray-quality crystals of either of the organometallic complexes until recently. When they finished the structural characterization of Zr(OEP)(etasup 5Csub 2Bsub 9Hsub 11) by X-ray crystallography, however, Arnold and co-workers published the synthesis and characterization of Zr(OEP)Clsub 2 and several organometallic complexes derived from it, including Zr(OEP)(CHsub 2SiMesub 3)sub 2 and Zr(OEP)(etasup 5-Csub 2Bsub 9Hsub 11). Here they present their results on the syntheses and characterization of Zr(por)Clsub 2 (por = OEP, TPP), Zr(TPP)Mesub 2, and Zr(OEP)(etasup 5-Csub 2Bsub 9Hsub 11) and the X-ray structure of Zr(TPP)Clsub 2(THF). 22 refs., 2 tabs.
Eine wabenartige Struktur weist das aus D6h‐symmetrischen Cucurbiturilmolekülen und Rubidiumionen aufgebaute eindimensionale Koordinationspolymer auf (siehe Bild). Die Cucurbiturilmoleküle sind ...übereinandergestapelt und koordinieren über ihre Carbonylgruppen an die dazwischenliegenden Rubidiumionen. Form und Symmetrie der Baueinheiten bedingen die Bildung von Koordinationspolymerketten, die so angeordnet sind, daß eine Gerüststruktur mit großen, linearen, hexagonalen Kanälen entsteht.
Vertical and lateral heterogeneous structures of two-dimensional (2D) materials have paved the way for pioneering studies on the physics and applications of 2D materials. A hybridized hexagonal boron ...nitride (h-BN) and graphene lateral structure, a heterogeneous 2D structure, has been fabricated on single-crystal metals or metal foils by chemical vapor deposition (CVD). However, once fabricated on metals, the h-BN/graphene lateral structures require an additional transfer process for device applications, as reported for CVD graphene grown on metal foils. Here, we demonstrate that a single-crystal h-BN/graphene lateral structure can be epitaxially grown on a wide-gap semiconductor, SiC(0001). First, a single-crystal h-BN layer with the same orientation as bulk SiC was grown on a Si-terminated SiC substrate at 850 oC using borazine molecules. Second, when heated above 1150 oC in vacuum, the h-BN layer was partially removed and, subsequently, replaced with graphene domains. Interestingly, these graphene domains possess the same orientation as the h-BN layer, resulting in a single-crystal h-BN/graphene lateral structure on a whole sample area. For temperatures above 1600 oC, the single-crystal h-BN layer was completely replaced by the single-crystal graphene layer. The crystalline structure, electronic band structure, and atomic structure of the h-BN/graphene lateral structure were studied by using low energy electron diffraction, angle-resolved photoemission spectroscopy, and scanning tunneling microscopy, respectively. The h-BN/graphene lateral structure fabricated on a wide-gap semiconductor substrate can be directly applied to devices without a further transfer process, as reported for epitaxial graphene on a SiC substrate.
Interaction of neutral ruthenium(II) complexes of the type RuHCl(CO)(PPh
3) (L-L′) where L-L′ = Ph
2
PCH
2
CH
2
PPh
2 (dppe),
1; Ph
2PCH
2CH
2CH
2PPh
2 (dppp),
2; Ph
2PCH
2CH
2AsPh
2 (arphos),
3 with ...AgClO
4 in the presence of L″ L″ = P(OMe)
3 or PME
3 yielded the new cationic ruthenium(II) complexes RuH(CO)(PPh
3)(L″)(L-L′)ClO
4 where L-L′ = dppe,
4; dppp,
5 arphos,
6; L″ = PMe
3,
4; P(OMe)
3,
5 and
6. All the complexes have been characterized by both analytical and spectroscopic (IR and
1H NMR) methods. The structure of a cationic complex
6, RuH(CO)(PPh
3)(P(OMe)
3) (arphos)ClO
4·n−C
5H
12, has been confirmed by single-crystal X-ray diffraction. The Ru atom is octahedrally coordinated with CO, PPh
3, and arphos in the equatorial plane and H and P(OMe)
3 in the axial positions. In the hydrogenation of cyclohexene, some relations between structures and catalytic activities have been studied. The cationic complexes have shown lower catalytic activities than their neutral analogues.
(±)-1,4-Di-
O-benzoyl-2,3-
O-isopropylidene-
myo-inositol (1) crystallises in the triclinic space group,
P1 with unit-cell dimensions
a = 10.432(2),
b = 11.595(4),
c = 12.654(2)
A
̊
,
α = 67.72(3),
β ...= 11.595(4),
γ = 12.654(2) degrees. (±)-1,4-
O-Dibenzoyl-5,6-
O-isopropylidene-
myo-inositol (2) crystallises in the monoclinic space group,
P2
1/n with unit-cell dimensions
a = 9.101(2),
b = 10.4900(9),
c = 22.806(4)
A
̊
,
α = 90,
β = 95.452(10),
γ = 90 degrees. The inositol ring of
cis-acetal 1 is flattened, whereas that of
trans-acetal 2 is more puckered compared to
myo-inositol. The acyl migration rates are discussed in terms of the crystalline conformations of 1 and 2.
