排序方式: 共有47条查询结果,搜索用时 140 毫秒
1.
The time delay experiment proposed by I.I. Shapiro in 1964 and conducted in the seventies was the most precise experiment
of general relativity until that time. Further experimentation has improved the accuracy level of both the time delay and
the light deflection experiments. A simulation model is proposed that involves only a simple mass and time transformation
factor involving velocity of light. The light deflection and the time delay experiments are numerically simulated using this
model that does not use the general relativistic equations. The computed values presented in this paper compare well with
recent levels of accuracy of their respective experimental results. 相似文献
2.
Rajendra Singh?Ghadwal Ram?C.?Mehrotra Anirudh?SinghEmail author 《Transition Metal Chemistry》2005,30(7):836-844
An entirely new class of heterobimetallic homoleptic glycolate complexes of the type Nb(OGO)3{Ta(OGO)2} [where G=CMe2CH2CH2CMe2 (G1) (3); CMe2CH2 CHMe(G2) (4); CHMeCHMe (G3) (5); CH2CMe2CH2 (G4) (6); CMe2CMe2(G5) (7); CH2CHMeCH2 (G6) (8); CH2CEt2CH2 (G7) (9); CH2CMe(Prn)CH2 (G8) (10)] have been prepared by the reactions of Nb(OGO)2(OGOH) [G=G1 (1a); G2 (1b); G3 (1c); G4 (1d); G5 (1e); G6 (1f); G7 (1g); G8 (1h)] with Ta(OGO)2 (OPri) (G=G1 (2a); G2 (2b); G3 (2c); G4 (2d); G5 (2e) G6 (2f); G7 (2g); G8 (2h). In addition to the novel derivatives (2)–(10), our earlier investigations on heterobimetallic glycolate-alkoxide derivatives have been extended to derivatives of the type
Nb(OGO)
[where M=A1 n=3, G=G3 (11);G4 (12); G6 (13) G7 (14); Gs (15); G9=CH2CH2CH2 (16) and M=Ti (n=4, G=G4) (17), Zr(n=4,G=G4) (18)], which are conveniently prepared by the reactions of metalloligands Nb(OGO)2(OGOH) [G=G3 (1c); G4 (1d); G6 (1f); G7 (1g); G8 (1h); G9 (1i)] with different metal alkoxides. All of these new complexes have been characterized by elemental analyses, molecular weight
determinations, and spectroscopic (I.r. and 1H, 27Al-n.m.r.) studies. Structural features of the new derivatives have been elucidated on the basis of molecular weight and spectroscopic
data. 相似文献
3.
Ghadwal Rajendra Singh Sharma Malti Singh Anirudh Mehrotra Ram C. 《Transition Metal Chemistry》2004,29(4):419-424
Complexes of the types VO(L)(R-deaH), VO(R-dea)(LH), and VO(L)(OGOH)[L = deprotonated form of N-(1-hydroxyethyl) naphthaldimine; R-dea = deprotonated form of a N-substituted diethanolamine, with R = H or Ph; G = CH2CH2, CHMeCHMe, CMe2CMe2, CHMeCH2CMe2, CMe2CH2CH2CMe2] have been prepared by the equimolar reactions of VO(OPr
i
)3, LH2, and an appropriate diethanolamine or glycol in benzene. All of these coloured solid complexes have been characterised by elemental (C, H, N, and V) analyses and by spectroscopic (i.r., electronic, 1H-, 51V-n.m.r) studies. The relative lability of the hydroxy group(s) of N-(1-hydroxyethyl)naphthaldiamine, diethanolamine, and glycol has also been investigated. 相似文献
4.
Dr. Mahendra K. Sharma Dr. Sebastian Blomeyer Beate Neumann Dr. Hans-Georg Stammler Priv.-Doz. Dr. Rajendra S. Ghadwal 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(35):8249-8253
The first divinyldiarsenes [{(NHC)C(Ph)}As]2 (NHC=IPr 3 a , SIPr 3 b ; IPr=C{(NAr)CH}2; SIPr=C{(NAr)CH2}2; Ar=2,6-iPr2C6H3) are reported. Compounds 3 a and 3 b were prepared by the reduction of corresponding chlorides {(NHC)C(Ph)}AsCl2 (NHC=IPr 2 a , SIPr 2 b ) with Mg. Calculations revealed a small HOMO–LUMO energy gap of 3.86 ( 3 a ) and 4.24 eV ( 3 b ). Treatment of 3 a with (Me2S)AuCl led to the cleavage of the As=As bond to restore 2 a , which is expected to proceed via the diarsane [{(IPr)C(Ph)}AsCl]2 ( 4 ). Remarkably, 4 as well as 2 a can be selectively accessed on treatment of 3 a with an appropriate amount of C2Cl6. Moreover, 3 a readily reacts with PhEEPh (E=Se or Te) at room temperature to give {(IPr)C(Ph)}As(EPh)2 (E=Se 5 a ; Te 5 b ), revealing the cleavage of As=As and E−E bonds and the formation of As−E bonds. Such highly selective stepwise oxidation ( 3 a → 4 → 2 a ) and bond metathesis ( 3 a → 5 a , b ) reactions are unprecedented in main-group chemistry. 相似文献
5.
Dr. Ramachandran Azhakar Dr. Rajendra S. Ghadwal Prof. Dr. Herbert W. Roesky Prof. Dr. Ricardo A. Mata Hilke Wolf Regine Herbst‐Irmer Prof. Dr. Dietmar Stalke 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(11):3715-3720
Three‐ and five‐membered rings that bear the (Si‐C‐S ) and (Si‐C‐C‐C‐S ) unit have been synthesized by the reactions of L SiCl ( 1 ; L =PhC(NtBu)2) and L′ Si ( 2 ; L′ =CH{(C?CH2)(CMe)(2,6‐iPr2C6H3N)2}) with the thioketone 4,4′‐bis(dimethylamino)thiobenzophenone. Treatment of 4,4′‐bis(dimethylamino)thiobenzophenone with L SiCl at room temperature furnished the [1+2]‐cycloaddition product silathiacyclopropane 3 . However, reaction of 4,4′‐bis(dimethylamino)thiobenzophenone with L′ Si at low temperature afforded a [1+4]‐cycloaddition to yield the five‐membered ring product 4 . Compounds 3 and 4 were characterized by NMR spectroscopy, EIMS, and elemental analysis. The molecular structures of 3 and 4 were unambiguously established by single‐crystal X‐ray structural analysis. The room‐temperature reaction of 4,4′‐bis(dimethylamino)thiobenzophenone with L′ Si resulted in products 4 and 5 , in which 4 is the dearomatized product and 5 is formed under the 1,3‐migration of a hydrogen atom from the aromatic phenyl ring to the carbon atom of the C? S unit. Furthermore, the optimized structures of probable products were investigated by using DFT calculations. 相似文献
6.
Falk Ebeler Dr. Yury V. Vishnevskiy Beate Neumann Dr. Hans-Georg Stammler Priv.-Doz. Dr. Rajendra S. Ghadwal 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(31):e202200739
Mesoionic dithiolates [(MIDtAr)Li(LiBr)2(THF)3] (MIDtAr={SC(NDipp)}2CAr; Dipp=2,6-iPr2C6H3; Ar=Ph 3 a , 3-MeC6H4 (3-Tol) 3 b , 4-Me2NC6H4 (DMP) 3 c ) and [(MIDtPh)Li(THF)2] ( 4 ) are readily accessible (in≥90 % yields) as crystalline solids on treatments of anionic dicarbenes Li(ADCAr) ( 2 a - c ) (ADCAr={C(NDipp)2}2CAr) with elemental sulfur. 3 a - c and 4 are monoanionic ditopic ligands with both the sulfur atoms formally negatively charged, while the 1,3-imidazole unit bears a formal positive charge. Treatment of 4 with (L)GeCl2 (L=1,4-dioxane) affords the germylene (MIDtPh)GeCl ( 5 ) featuring a three-coordinated Ge atom. 5 reacts with (L)GeCl2 to give the Ge−Ge catenation product (MIDtPh)GeGeCl3 ( 6 ). KC8 reduction of 5 yields the homoleptic germylene (MIDtPh)2Ge ( 7 ). Compounds 3 a - c and 4 – 7 have been characterized by spectroscopic studies and single-crystal X-ray diffraction. The electronic structures of 4 – 7 have been analyzed by DFT calculations. 相似文献
7.
Dr. Dennis Rottschäfer Beate Neumann Dr. Hans-Georg Stammler Dr. Tetiana Sergeieva Dr. Diego M. Andrada Dr. Rajendra S. Ghadwal 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(9):3055-3064
Herein, we report the first 1,4-diphosphinine-1,4-diide compound [(ADCPh)P]2 ( 5-Ph ) (ADCPh=PhC{(NDipp)C}2; Dipp=2,6-iPr2C6H3) derived from an anionic dicarbene (ADCPh) as a red crystalline solid. Compound 5-Ph containing a 16π-electron planar fused-tricyclic ring system was obtained by the 4e reduction of [(ADCPh)PCl2]2 ( 4-Ph ) with Mg (or KC8) in a quantitative yield. Experimental and computational results imply that the central 8π-electrons C4P2 ring of 5-Ph , which is fused between two 6π-electrons C3N2 aromatic rings, is antiaromatic. Thus, each of the phosphorus atoms of 5-Ph has two electron-lone-pairs, one in a p-type orbital is in conjugation with the C=C bonds of the C4P2 ring, while the second resides in a σ-symmetric orbital. This can be shown with the gold complex [(ADCPh)P(AuCl)2]2 ( 6-Ph ) obtained by reacting 5-Ph with (Me2S)AuCl. A mixture of 5-Ph and 4-Ph undergoes comproportionation in the presence of MgCl2 to form the intermediate oxidation state compound [(ADCAr)P]2(MgCl4) ( 7-Ph ), which is an aromatic species. 相似文献
8.
9.
10.
Palladium‐Catalyzed Direct C2‐Arylation of an N‐Heterocyclic Carbene: An Atom‐Economic Route to Mesoionic Carbene Ligands 下载免费PDF全文
Dr. Rajendra S. Ghadwal Sven O. Reichmann Dr. Regine Herbst‐Irmer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(11):4247-4251
Blocking the C2 position of an imidazole‐derived classical N‐heterocyclic carbene (NHC) with an aryl group is an essential strategy to establish a route to mesoionic carbenes (MICs), which coordinate to the metal via the C4 (or C5) carbon atom. An efficient catalytic route to MIC precursors by direct arylation of an NHC is reported. Treatment of 1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene (IPr) with an aryl iodide (RC6H4I) in the presence of 0.5 mol % of [Pd2(dba)3] (dba=dibenzylideneacetone) precatalyst affords the C2‐arylated imidazolium salts {IPr(C6H4R)}I (R=H, 4‐Me, 2‐Me, 4‐OMe, 4‐COOMe) in excellent (up to 92 %) yields. Treatment of {IPr(C6H5)}I with CuI and KN(SiMe3)2 exclusively affords the MIC–copper complex [(IPrPh)CuI]. 相似文献