A Fast Catalytic Process of Transfer of a Phosphorus Atom: How Folding of the Reagent is Related to its Catalytic Activity. A Possible Correlation with Rna Behavior

Abstract

A simple and very fast process of transfer of a phosphorus atom, performed by a simple molecule acting as catalyst in an almost infinite catalytic cycle is described. The catalyst donates a P atom to a mixture of two different Grignard reagents giving, in a very fast and in a highly selective manner, only one phosphorus-containing compound with an enormous rate enhancement with respect to the corresponding no-catalyzed reaction which gives a final cluttered mixture of many organophosphorus products. The focal factor to explain this highly selective process of P transport lies in the folded structure of the reagent with particular angles around the phosphorus atom which can facilitate the formation of cyclic trigonal bipyramidal pentacoordinated species and then its catalytic activity. In a similar manner, RNA can adopt, in a precise position, a particular three-dimensional structure that might facilitate the formation of pentacoordinated species leading to the catalytic function.     

Structure of novel N-fluorosilylmethyl-N-isopropylureas

Novel N-isopropyl-N',N'-dimethyl-N-(silylmethyl)ureas Me₂NC(O)N(Prⁱ)CH₂SiMe_nX_3–n (X = OEt, F; n = 0–2) were synthesized, and their structure was confirmed by ¹H, ¹³C and ²⁹Si NMR spectroscopy. According to NMR data, the silicon atom of the fluorosilanes (X = F) is pentacoordinated. The X-ray diffraction analysis of the (trifluorosilyl)methylcontaining urea showed that it exists as (O–Si) chelate with intramolecular dative bond C=O→Si (1.880 Å).     

平面四配位和五配位的B6S5团簇

采用B3LYP/def2-TZVP优化和在耦合簇方法(CCSD)单点水平下, 将$B_{6}S^{n}_{5}$ (n=0, +1, +2)作为基础结构研究证实了S原子对于形成B平面多配位结构具有良好的作用. 研究发现, $B_{6}S^{n}_{5}$ (n=0, +1, +2) 3种价态下最稳定和次稳定结构均为纯平面结构, 仅在不同电子数下两者的能量次序发生改变. 中性的B₆S₅因满足18电子规则其最稳定结构具有D_5h对称性, 且中心B为平面五配位. 在$B_{6}S^{+}_{5}$和$B_{6}S^{2+}_{5}$中, 其17电子和16电子时的最稳定结构中的所有B均为平面四配位. 18电子的B₆S₅更为稳定.     

SYNTHESIS,STRUCTURE AND THERMOLYSIS OF PENTACOORDINATE 1,2-OXASTIBETANES

Pentacoordinate 1,2-oxastibetanes have been synthesized and characterized by x-ray crystallographic analysis and NMR spectroscopy. Thermolyses of a pentacoordinate 1,2-oxastibetane were carried out under various conditions to give the corresponding oxirane with retention of configuration, the oxirane with inversion of configuration and the olefin respectively.     

一个具有四方锥和三角双锥构型的线性混合桥连三核铜配合物

以反式-3-[N,N-二(2-吡啶甲基)氨甲基]-2-羟基-5-甲基苯甲醛肟(H₂L)为配体,合成了一个新颖的线性三核铜(Ⅱ)配合物[Cu₃L₂(py)](ClO₄)₂·2THF (1)(py=吡啶,THF=四氢呋喃),对其进行了红外、紫外、热重和单晶结构表征。配合物1属于单斜晶系,空间群为C2/c,a=2.969 0(7) nm,b=1.302 8(3) nm,c=2.057 4(9) nm,β=132.435(2)°,V=5.873(3) nm³,Z=4,R₁=0.047 9。单晶结构表明,这是一个混合桥(-N-O-和μ₂-O-)连的线性五配位三核铜(Ⅱ)配合物:每个铜均由3个氮原子和2个氧原子配位,中间的铜为扭曲的三角双锥构型,而两侧的铜为扭曲的四方锥构型。变温磁化率显示1的铜离子间存在中等的反铁磁性(J=-33.3(5) cm^-1)。     

Trifluoromethylation and pentafluorophenylation of enamines

A reaction of enamines with Me₃SiCF₃ and Me₃SiC₆F₅ in the presence of carboxylic acids leading to α-CF₃-and α-C₆F₅-substituted amines has been studied. 3-Cyanobenzoic acid was found to be the optimal promoter of these reactions. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1466–1468, August, 2007.     

N-(Chlorodimethylsilyl)methyl anilides: synthesis and structure

N-(Chlorodimethylsilyl)methyl anilides of formula RC(O)N(C₆H₄X)CH₂SiMe₂Cl (R = Me, Ph; X = H, Me, Cl) were obtained by the reaction of N-TMS-containing anilides with ClCH₂Si(Hal)Me₂ (Hal = F, Cl). The silicon atom in these compounds is pentacoordinate according to the results of NMR and X-ray diffraction analysis.     

直接由SiO2合成双羟基四配位硅化物及其结构表征

化合物;直接由SiO2合成双羟基四配位硅化物及其结构表征     

Phosphoryl Transfer Enzymes and Hypervalent Phosphorus Chemistry: A Keynote Lecture of the 7th International Conference on Heteroatom Chemistry

The coordination tendencies of phosphorus to form a hexacoordinated state from a pentacoordinated state which might assist in describing mechanistic action of phosphoryl transfer enzymes are delineated. The factors discussed include substrate and transition or intermediate state anionicity; hydrogen bonding; packing effects, i.e., van der Waals forces; the ease of formation of hexacoordinate phosphorus from lower coordinate states; and the pseudorotation problem common to nonrigid pentacoordinate phosphorus. In view of the work reported in this account and recent work on enzyme promiscuity and moonlighting activities, it is suggested that donor action should play a role in determining active-site interactions in phosphoryl transfer enzyme mechanisms.