Boron-Boron Quadruple Bond in Li3B2- and Li4B2 Clusters

2021 ◽  
Author(s):  
Amlan Jyoti Kalita ◽  
Shahnaz Sultana Rohman ◽  
Chayanika Kashyap ◽  
Sabman Swabaka Ullah ◽  
Indrani Baruah ◽  
...  
Keyword(s):  
Quadruple Bond

Homopolar quadruple bonding to first row p-block elements is expected due to the presence of four valence orbitals accessible for bonding. Although, quadruple bonding in C2 has been proposed, no...

Room-Temperature Chemical Synthesis of C2

2019 ◽  
Author(s):  
Kazunori Miyamoto ◽  
Shodai Narita ◽  
Yui Masumoto ◽  
Takahiro Hashishin ◽  
Mutsumi Kimura ◽  
...  
Keyword(s):  
Chemical Synthesis ◽  
Ground State ◽  
Room Temperature ◽  
Chemical Species ◽  
Quadruple Bond ◽  
Photon Excitation ◽  
Physical Energy ◽  
Theoretical Predictions ◽  
Carbon Arc ◽  
Inherent Nature

Diatomic carbon (C<sub>2</sub>) is historically an elusive chemical species. It has long been believed that the generation of C<sub>2 </sub>requires extremely high “physical” energy, such as an electric carbon arc or multiple photon excitation, and so it has been the general consensus that the inherent nature of C<sub>2 </sub><i>in the ground state </i>is experimentally inaccessible. Here, we present the first “chemical” synthesis of C<sub>2 </sub>in a flask at <i>room temperature or below</i>, providing the first experimental evidence to support theoretical predictions that (1) C<sub>2 </sub>has a singlet biradical character with a quadruple bond, thus settling a long-standing controversy between experimental and theoretical chemists, and that (2) C<sub>2 </sub>serves as a molecular element in the formation of sp<sup>2</sup>-carbon allotropes such as graphite, carbon nanotubes and C<sub>60</sub>.

The electronic nature of the metal-metal quadruple bond: variable photon energy photoelectron spectroscopy of Mo2(O2CCH3)4

1992 ◽  
Vol 114 (26) ◽  
pp. 10492-10497 ◽  
Author(s):  
Dennis L. Lichtenberger ◽  
Charles D. Ray ◽  
Frank Stepniak ◽  
Yu Chen ◽  
J. H. Weaver
Keyword(s):  
Photon Energy ◽  
Photoelectron Spectroscopy ◽  
Electronic Nature ◽  
Quadruple Bond ◽  
Metal Metal

Tetracarbanilanilidodichromium(II): A Clue to the Understanding of the CrCr Quadruple Bond

1979 ◽  
Vol 18 (11) ◽  
pp. 874-875 ◽  
Author(s):  
F. Albert Cotton ◽  
William H. Ilsley ◽  
Wolfgang Kaim
Keyword(s):  
Quadruple Bond

Preparation and characterization of a new series of Cr(II) hydroborates

1995 ◽  
Vol 73 (7) ◽  
pp. 1126-1134 ◽  
Author(s):  
Michel Dionne ◽  
Shoukang Hao ◽  
Sandro Gambarotta
Keyword(s):  
Trinuclear Complex ◽  
Synthesis And Characterization ◽  
Crystal Data ◽  
X Ray ◽  
X Ray Crystallography ◽  
Quadruple Bond ◽  
Quadruple Bonds ◽  
Reaction Proceeds

The synthesis and characterization of a new series of mono-, di-, and trinuclear Cr(II) borohydride compounds is described. The reaction of CrCl2(TMEDA) with two equivalents of NaBH4 afforded the thermally unstable (TMEDA)Cr(BH4)2 (1), which was converted by treatment with pyridine into the octahedral monomeric (Py)4Cr(BH4)2 (2). The reaction proceeds via formation of an intermediate trinuclear complex {[(TMEDA)(Py)Cr(η2-BH4)]2[(Py)2Cr(η2-BH4)2]}(µ,η1-BH4)2 (3), which was isolated and characterized by X-ray crystallography. Reaction of 1 and 2 with both CO2 and RN=C=NR (R = Cy, iPr) afforded hydride insertion and formation of the corresponding diamagnetic lantern-type Cr(II) formate (HCO2)4Cr2Py2 (4) and formamidinate compounds [RNC(H)NR]2Cr2(µ-BH)4 (R = Cy (5a), iPr (5b)), respectively, with supershort Cr—Cr quadruple bonds. The structures of 1, 2, 3, and 5b were elucidated by X-ray analysis. Crystal data are as follows. 1: C6H24N2B2Cr, monoclinic, Cc, a = 8.517(2) Å, b = 15.921(5) Å, c = 9.624(2) Å, β = 115.59(1)°, Z = 4, R = 0.022, Rw = 0.029; 2: C28H44N4B2O2Cr, monoclinic, P21/n, a = 12.021(1) Å, b = 15.555(1) Å, c = 15.723(1) Å, β = 90.13(2)°, Z = 4, R = 0.074, Rw = 0.086; 3: C32H76N8B6Cr3, monoclinic, P21/n, a = 8.515(1) Å, b = 14.525(1) Å, c = 18.286(2) Å, β = 91.38(1)°, Z = 2, R = 0.051, Rw = 0.060; 5b: C21H49N6BCr2, monoclinic, C2/c, a = 17.000(1) Å, b = 9.033(1) Å, c = 19.160(1) Å, β = 105.579(9)°, Z = 4, R = 0.069, Rw = 0.078. Keywords: divalent chromium, borohydride, Cr—Cr quadruple bond.

scholarly journals Interaction of dirhenium(III) tryptophan complex compound with DNA and protein

2021 ◽  
pp. 35-40
Author(s):  
O.A. Holichenko ◽  
◽  
N.I. Shtemenko ◽  
A.A. Ovcharenko ◽  
A.V. Shtemenko
Keyword(s):  
Complex Compound ◽  
Blue Shift ◽  
Binding Activity ◽  
Significant Shift ◽  
Amino Acid Residues ◽  
Conjugated Systems ◽  
Quadruple Bond ◽  
G4 Dna ◽  
Main Protein ◽  
Dna Silencing

We report about the interactions of dirhenium(III) compound cis-[Re2(Trp)2Cl4(CH3CN)2]Cl2 (I) with bovine serum protein (BSA) and guanine (G4) quadruplexes DNA by UV-Vis titration. Addition of I to BSA led to the interaction between these compounds with binding constant 5.6103 M–1 and hyperchromism (20.9%) of the main protein absorption band (280 nm). These results support our assumption about formation of the additional conjugated systems during the process of interaction with BSA. Stabilization of the quadruple bonded rhenium(III) complex compound was shown in the presence of BSA (the rate of destruction was reduced), that may be explained by interaction between amino acid residues of BSA and quadruple bond of dirhenium(III) complex compound. In addition, we have obtained data about strong hyperchromism (up to 100%) and significant shift of the maximum of absorption (blue shift) towards UV (2–9 nm) and visible (22 nm) regions in the spectra of mixtures G4s and I, that, in our opinion, correlated with a conformational change in DNA and with formation of additional conjugated systems around quadruple bond of I. In a whole, our work confirms the strong binding activity of a cluster dirhenium(III) compound towards G4 quadruplexes, that exceed the binding activity to proteins and witness to preferential interactions of I with G4 DNA in a living cell. These results may be used in DNA "silencing technology" and "antisense therapy".

First Examples of Homogeneous Catalytic Cyclotrimerization and Polymerization of Phenylacetylene and Copolymerization of Phenylacetylene and Norbonene with Dinuclear Complexes Containing Unbridged Metal-Metal Quadruple Bond

2003 ◽  
Vol 68 (6) ◽  
pp. 1094-1104 ◽  
Author(s):  
Konstantinos Mertis ◽  
Stavros Arbilias ◽  
Demos Argyris ◽  
Nikos Psaroudakis ◽  
Jiří Vohlídal ◽  
...  
Keyword(s):  
Dinuclear Complexes ◽  
Addition Reactions ◽  
Polymer Yield ◽  
Quadruple Bond ◽  
Metal Metal ◽  
Medium Activity ◽  
Copolymer Structure ◽  
Almost All ◽  
Ligand Addition ◽  
Low Activity

First examples of application of dinuclear complexes containing unbrigded metal-metal quadruple bond as catalysts in cyclotrimerization, oligomerization and polymerization of substituted acetylene are reported. The d4-d4 dinuclear complexes (Bu4N)2[Re2X8] (1) (1a, X = Cl; 1b, X = Br and 1c, X = I) show low activity and the complex [Mo2Cl4(MeOH)2(PPh3)2] (2) medium activity in cyclotrimerization and oligomerization of phenylacetylene (PA). In contrast, the tungsten-based d4-d4, complex Na4[W2Cl8] (3) exhibits high polymerization activity (polymer yield above 90%) and ca 75% cis-selectivity in tetrahydrofuran. The activity and cis-stereoselectivity of these single-component catalysts decrease in the order 3 >> 2 >> 1, which is proportional to the metal-metal quadruple bond propensity towards ligand addition reactions. Complex 3 induces metathesis polymerization of norbornene (NBE) to poly(cyclopentene-1,3-diylvinylene) with 82% cis-selectivity and copolymerization of PA and NBE to almost all-cis high-molecular-weight copolymer containing cyclopentene-1,3-diylvinylene units, which is free of longer sequences of both PA and NBE units. This suggests that also homopolymerization of PA with 3 proceeds by the metathesis mechanism and that the PA/NBE copolymer structure is close to the alternating one.

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