다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

8.4.5. Nitromercuration Reactions 3878 9. Hydroamination of Alkenes and Alkynes under Microwave Irradiation 3878 * To whom correspondence should be addressed. Phone: +49 241 8

Hydroamination: direct addition of amines to alkenes and alkynes.

: The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

N-heterocyclic carbene analogues with low-valent group 13 and group 14 elements: syntheses, structures, and reactivities of a new generation of multitalented ligands.

Four-step reduction of dpp-bian with sodium metal: crystal structures of the sodium salts of the mono-, di-, tri- and tetraanions of dpp-bian.

Novel neutral antimony(V) complexes were isolated as crystalline materials and characterized by IR and NMR spectroscopy: o-amidophenolate complexes [4,6-di-tert-butyl-N-(2,6-dimethylphenyl)-o-amidophenolato]triphenylantimony(V) (Ph3Sb[AP-Me], 1) and [4,6-di-tert-butyl-N-(2,6-diisopropylphenyl)-o-amidophenolato]triphenylantimony(v) (Ph3Sb[AP-iPr], 2); catecholate complexes (3,6-di-tert-butyl-4-methoxycatecholato)triphenylantimony(V) (Ph3Sb[(MeO)Cat], 3), its methanol solvate 3⋅CH3OH (4); (3,6-di-tert-butyl-4,5-di-methoxycatecholato)triphenylantimony(V) (Ph3Sb[(MeO)2Cat], 5) and its acetonitrile solvate 5⋅CH3CN (6). Complexes 1–7 were synthesized by oxidative addition of the corresponding o-iminobenzoquinones or o-benzoquinones to Ph3Sb. In the case of the phenanthrene-9,10-diolate (PhenCat) ligand, two different complexes were isolated: Ph3Sb[PhenCat] (7) and [Ph4Sb]+[Ph2Sb(PhenCat)2]− (8). Complexes 7 and 8 were found to be in equilibrium in solution. Molecular structures of 2, 4, 6, and 8 were determined by X-ray crystallography. Complexes 1–7 reversibly bind molecular oxygen to yield Ph3Sb[L-Me]O2 (9), Ph3Sb[L-iPr]O2 (10), Ph3Sb[(MeO)L′]O2 (11), Ph3Sb[(MeO)2L′]O2 (12) and Ph3Sb[PhenL′]O2 (13), which contain five-membered trioxastibolane species (where L is the O,O′,N-coordinated derivative of a 1-hydroperoxy-6-(N-aryl)-iminocyclohexa-2,4-dienol, and L′ the O,O′,O′′-coordinated derivative of 6-hydroperoxy-6-hydroxycyclohexa-2,4-dienone). Complexes 9–13 were characterized by IR and 1H NMR spectroscopy and X-ray crystallography.

Triphenylantimony(v) catecholates and o-amidophenolates: reversible binding of molecular oxygen.

In 2004, Carmona and co-workers reported the isolation of the first molecular zinc compound having a direct metal– metal bond, [Cp*Zn ZnCp*] (1a ; Cp*=C5Me5). Following this pioneering work, Robinson and co-workers synthesized the three-coordinate zinc ketiminate derivative [{HC(CMeNAr)2}Zn Zn{HC(CMeNAr)2}] (2) (Ar= 2,6iPr2C6H3). [2] A further breakthrough in this field was the synthesis by Power and co-workers of the two-coordinate compound, [Ar’Zn ZnAr’] (3) (Ar’= 2,6-(2,6iPr2C6H3)2C6H3), in which stabilization of Zn Zn bonding was achieved using a bulky aryl ligand. While our paper was being submitted, another dizincocene, [(C5Me4Et)Zn Zn(C5Me4Et)] (1b), was prepared and investigated by X-ray crystallography as well as computationally. So far, compounds 1–3 are the only examples of zinc organic derivatives which have a direct Zn Zn bond. The metal–metal bonds in these compounds (1a : 2.305(3); 1b : 2.295(3); 2 : 2.3586(7); 3 : 2.3591(9) ?) are significantly shorter than the sum of zinc covalent radii (2.5 ?). Density functional theory (DFT) calculations (B3LYP) for 1–3 showed that in 1a and 2 the metal 4s orbitals mainly contribute to the Zn Zn bond, whereas in 3 this bond is formed from the overlap of 4pz orbitals. Earlier we showed that the use of 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-bian) allowed the preparation of monomeric complexes of Group 1, 2, and 13 metals with the dpp-bian ligand in its anionic forms ([dpp-bian] , n= 1–4). Aggregation of alkaline-earth or aluminum complexes of [dpp-bian] (n= 1, 2) is prevented by two factors: the rigidity of the diimine fragment and the bulkiness of 2,6iPr2C6H3 substituents. Also the dpp-bian is able to stabilize the low oxidation state of germanium, thus providing twoand three-coordinate Ge species with the dianionic and radical-anionic dpp-bian ligand, [(dpp-bian)Ge] and [(dppbian)GeCl]. Being inspired by the development of the Zn Zn chemistry and to get more insight in solution behavior of zinc–zinc-bonded species we have attempted the synthesis of a Zn Zn compound stabilized with the radical-anionic dppbian. Herein we report on the synthesis and characterization by single-crystal X-ray analysis and ESR spectroscopy of the first zinc–zinc-bonded compound supported by radicalanionic ligands, [(dpp-bian)Zn Zn(dpp-bian)] (4), as well as examination of its electronic structure by computation (DFT). In contrast to magnesium, which reacts with dpp-bian in the presence of 1 mol% of MgI2 to give quantitative formation of [(dpp-bian)Mg(thf)3], zinc metal does not react with dpp-bian in the presence of ZnI2 in THF under the same conditions. However, stirring of dpp-bian with a large excess of zinc granules in THF in the presence of 0.5 mol equivalents of ZnI2 (formed in situ from the Zn and I2 in THF) at 20 8C for several minutes affords the cherry-red compound [{(dppbian)ZnI}2] (5) in 64% yield (Scheme 1). In solution compound 5 gives an ESR signal (2-methyltetrahydrofuran (Me-THF), 280 K: septet, gi= 2.0027, ai( I)= 0.24 mT, ai(2H N)= 0.51 mT) which clearly indicates the presence of the dpp-bian radical-anion. The N hyperfine coupling constant in 5 is only slightly different to those in Zn–DAD (DAD= 1,4-di-tert-butyl-1,3-diazadiene) radical-anionic species such as [(DAD)C Zn(DAD)]OTf

[(dpp‐bian)ZnZn(dpp‐bian)]: A Zinc–Zinc‐Bonded Compound Supported by Radical‐Anionic Ligands

Reversible Binding of Dioxygen by a Non-Transition-Metal Complex

A series of new yttrium complexes supported by the bulky enediamido dianionic ligand DAB2− (DAB2− = (2,6-C6H3iPr2)NC(Me)═C(Me)N(2,6-C6H3iPr2)2−), that is, {DAB}Y(THF)2(μ-Cl)2Li(THF)2 (1), {DAB}Y(OtBu)(THF)(DME) (2), and {{DAB}Y(BH4)2}{Li(DME)3} (3), was synthesized by salt metathesis. The complexes were isolated after recrystallization in 73, 66, and 52% yield, respectively, and characterized in solution by NMR and in the solid state by single-crystal X-ray diffraction studies. In complex 1, the DAB2− ligand is bonded to the metal center via two covalent Y—N bonds, while in complexes 2 and 3 additional η2-coordination of the C═C bond to the metal atom is observed, both in solution and in the solid state. The tert-butoxide and borohydride complexes 2 and 3 act as monoinitiators for the room temperature ring-opening polymerization of racemic lactide and β-butyrolactone, providing atactic polymers with controlled molecular weights and relatively narrow polydispersities (Mw/Mn = 1.15−1.82). Effectively immort...

Yttrium Complexes Supported by Linked Bis(amide) Ligand: Synthesis, Structure, and Catalytic Activity in the Ring-Opening Polymerization of Cyclic Esters

Georgy K. Fukin

Papers

Four-step reduction of dpp-bian with sodium metal: crystal structures of the sodium salts of the mono-, di-, tri- and tetraanions of dpp-bian.

Triphenylantimony(v) catecholates and o-amidophenolates: reversible binding of molecular oxygen.

[(dpp‐bian)ZnZn(dpp‐bian)]: A Zinc–Zinc‐Bonded Compound Supported by Radical‐Anionic Ligands

Reversible Binding of Dioxygen by a Non-Transition-Metal Complex

Yttrium Complexes Supported by Linked Bis(amide) Ligand: Synthesis, Structure, and Catalytic Activity in the Ring-Opening Polymerization of Cyclic Esters