六核钴原子簇化学——Ⅲ.一些含Co_6八面体簇骼的原子簇化合物的合成、结构和电化学性质

(R_3P)_(4-n)CoX_n(R=Ph,Et等;X=Cl,Br;n=1,2)与Na_2E_x(E=S,Se;x=1,2)在DMF或DMF/乙醇介质中反应得到了一系列六核钴的原子簇化合物Co_6(μ_3-E)_8(PR_3)_6.这些化合物含有正规的或畸变的Co_6八面簇骼.化合物可以用I_2氧化生成正一价的簇合物而不改变簇骼的几何构型.反过来,正一价的簇合物也可以被苊烯钠还原生成中性的簇合物.本文还研究了这些化合物的电化学性质并提出了氧化还原反应的电子传递过程。     

簇合物C03(CO)7(μ3-S) [μ,η2-CNP(S)(C6H4OCH3)OC(Ph)CH]和Co3(CO)7(μ3-S) [μ,η2-SCNC(CH3)2P(S)(Cl)N(Ph)]的合成与晶体结构

用Co2(CO)8分别与两个杂环配体C(S)NHP(S) (C6H4OCH3)OC(Ph)CH (L1)和C(S)NHC(CH3)2P(S) (CI)N(Ph) (L2)反应.合成两个新的三核钴羰基硫簇合物Co3(CO)7(μ3-S) [μ,η2-CNP(S) (C6H4OCH3)OC(Ph)CH] (Ⅰ)和Co3(CO)7(μ3-S) [μ,η2-SCNC(CH3)2P(S) (CI) N(Ph)] (Ⅱ).用元素分析,IR,1H NMR,31P NMR 及 MS谱表征了它们的结构,同时用X射线衍射法测定了它们的晶体分子结构,二者属于三斜晶系,P1空间群,I的晶胞参数为:a=0.84768(1)nm,b=1.19049(3)nm,c=1.43639(1)nm,α=86.926(1)°,β=81.60l(3)°,γ=88.535(2)°,V=1.4318(5)nm3,Z=2,Dc=1.641g@em-3,F(000)=716,μ=1.893mm-1,R=0.0602,Rw=0.1515.Ⅱ的晶胞参数为:a=1.2050(2)nm,b=1.2448(2)nm,c=0.8951(2)nm,α=97.49(1)°,β=93.552(4)°,γ=108.432(3)°,V=1.2554(3)nm3,Z=2,Dc=1.84lg@cm-3,F(000)=690,μ=2.419mm-1,R=0.0423,Rw=0.1075.Ⅰ和Ⅱ的分子骨架Co3S为三角锥构型,S作为面桥基配体,所有C0作为端基配体与三个Co原子成键.I中含有CoCoCN四元环组件,Ⅱ中含有CoCoSCN五元环组件.     

Fe3（Co）9（μ3—S）2的P（YR）3（Y=O,S）取代衍生物的合成和结构

用Fe_3(CO)_9(μ_3-S)_2和P(YR)_3(Y=O,S)在温和条件下反应,获得8种一取代和二取代新的簇合物,发现Fe_3(CO)_9(μ_3-S)_2和P(OR)_3有新的二取代方式,进而合成了另8种具有新的结构的二取代簇合物。对这些簇合物进行了元素分析和IR、~1H NMR、MS表征,并对Fe_3(CO)_7(μ_2-CO)·[P(O-cyclo-C_6H_(11)](μ_3-S)(Ⅷ)进行了X光单晶结构分析。     

[μ-PhC(O)S](μ-RS)Fe_2(CO)_6与(μ-R~1S)(μ-XMgS)Fe_2(CO)_6新奇反应的研究——孪合簇合物[(μ-RS)Fe_2(CO)_6](μ_4-S)[μ-R~1S)Fe_2(CO)_6]的合成、鉴定及形成机理

通过(μ-RS)(μ-XMgS)Fe_2(CO)_6与PhC(O)Cl反应合成了4个新苯甲酰配合物[μ-PhC(O)S](μ-RS)Fe_2(CO)_6(R=Me,Et,n—Bu,CH_2=CHCH_2). 它们进一步与(μ-R~1S)(μ-XMgS)Fe_2(CO)_6反应得8个不同 R,R~1基的孪合簇合物[(μ-RS)Fe_2(CO)_6](μ_4-S)[(μ-R~1S)Fe_2(CO)_6].其中R=n-Bu,R~1=Ph的配合物经X射线单晶结构分析表明是由1个μ_4-S将2个碎片PhS Fe_2(CO)_6及n-BuSFe_2(CO)_6螺结在一起的.其空间群为P—1; a=9.028(3),b=10.386(1),c=16.723(5)A;α=87.70(2),β=75.67(2),γ=82.26(2)°; Z=2; D_x=1.743g/cm~3.最终偏离因子R=0.031.     

四面体手性簇合物CpMo(RCp)WFe(CO)~7(μ~3-S)和CpW(RCp)MoFe(CO)~7 (μ~3- S)的合成及结构表征(R=CO~2Et,COMe,n-Bu)

利用等瓣置换法,通过M*[(R-Cp)M1(CO)3](R=CO2Et,COMe;M*=Na;R=n-Bu;M*=Li)与CpM2FeCo(CO)8(μ3-S)反应,得到六种环戊二烯配体含有较大取代基的含硫四面体手性簇合物(R-Cp)M1CpM2Fe(CO)7(μ3-S)(I-3:M1=W,M2=Mo,R=CO2Et;Ⅱ:M1=W,M2=Mo,R=COMe;Ⅲ:M1=W,M2=Mo,R=n-Bu;Ⅳ-2:M1=Mo,M2=W,R=CO2Et;V:M1=Mo,M2=W,R=COMe;Ⅵ:M1=Mo,M2=W,R=n-Bu).通过元素分析,IR,1H/13C NMR对合成的簇合物结构进行了表征,并讨论了反应途径.     

含硫磷桥基的两核铁羰基簇合物的合成和晶体结构

Fe3(CO)12与杂环二硫代次膦酸盐SP(C6H4OR)(S)N(C6H5)NC(Me)(R=Me,Et)反应,得到两个新的含硫磷桥基的双核铁羰基簇合物Fe2(CO)6[μ-η2-SC(Me)NN(C6H5)P(C6H4OMe)](Ⅰ)和Fe2(CO)6[μ-η2-SC(Me)NN(C6H5)P(C6H4OEt)](Ⅱ),以及簇合物Fe3(CO)9(μ3-S)2(已知).对它们进行了元素分析,IR,1HNMR和MS等谱学表征,并用X-ray衍射技术测定了(Ⅰ)的晶体结构.该晶体属单斜晶系,P2(1)/n空间群,晶胞参数a=11.192(2)A,b=14.272(3)A,c=16.281(3)A,β=108.22(3).,V=2470.2(8)A3,Z=4.两核簇合物中含有两个桥基Fe-S-Fe和Fe-P-Fe,而且-C(7)-N(2)-N(1)-链连结在S、P原子间,形成了两个六员螯环Fe(1)SCNNP和Fe(2)PNNCS,增强了簇合物的稳定性.     

Co3(CO)7(μ3-S)(μ,η2-SCNR2)的合成和晶体结构

Co2(CO)8与4个二硫代双(烷基硫代甲酰胺)类前配体[R2NC(S)S]2反应,得4个含烷基硫代甲酰胺基的三核钴羰基硫簇合物.通过元素分析、IR、1H NMR和MS等方法表征了它们的结构,用X射线衍射法测定了其中一个簇合物Co3(CO)7(μ3-S)[μ,η2-SCN(i-Pr)2](Ⅲ)的晶体结构.晶体属单斜晶系,P21/n空间群,晶胞参数a=1.145 2(2)nm,b=1.502 8(3)nm,c=1.2144(2)nm,a=90°,β=92.15(3)°,γ=90°,V=2.088 5(7)nm3,Z=4,F(000)=1 096,Dc=1.747 mg·m-3,GOF(F2)=0.835,μ=2.588 nm-1.最终因子R[I＞2σ(I)]=0.040 7,Rw=0.062 4.     

六核钴原子簇化学 3: 一些含Co~6八面体簇骼的原子簇化合物的合成、结构和电化学性质

(R~8P)~4-nCoX~n(R=Ph,Et 等;X=C,B=1,2)与Na~E~x(E=S,Se;X=1,2)在DMF或DMF/乙醇介质中反应得到了一系列六核钴的原子簇化合物Co~6(μ~3-E)~8(PR~3)~6.这些化合物含有正规的或畸变的Co~6八面簇骼.化合物可以用I~2氧化生成正一价的簇合物而不改变簇骼的几何构型,反达来,正一价的簇合物也可以被苊烯钠还生成中性的簇合物.本文还研究了这些化合物的电化学性质并提出了氧化还原反应的电子传递过程.     

六核钴原子簇化学 3: 一些含Co~6八面体簇骼的原子簇化合物的合成、结构和电化学性质

(R~8P)~4-nCoX~n(R=Ph,Et 等;X=C,B=1,2)与Na~E~x(E=S,Se;X=1,2)在DMF或DMF/乙醇介质中反应得到了一系列六核钴的原子簇化合物Co~6(μ~3-E)~8(PR~3)~6.这些化合物含有正规的或畸变的Co~6八面簇骼.化合物可以用I~2氧化生成正一价的簇合物而不改变簇骼的几何构型,反达来,正一价的簇合物也可以被苊烯钠还生成中性的簇合物.本文还研究了这些化合物的电化学性质并提出了氧化还原反应的电子传递过程.     

钼簇合物反应性能的研究-SbCl3和具有松散配位三核钼簇合物的加合反应及其产物的晶体结构

报道具有松散配位的三核钼簇合物{Mo3(μ3-S)(μ-S)3[S2P(OEt)2]4.L(L'=H2O,C3H3ON,和SbCl3在HCl-EtOH中加合反应及其产物{Mo3(μ3-S)[(μ-S)3.SbCl3].[S2P(OEt)2]4(C2H5OH)}(C2H5OH)和{Mo3(μ3-S)[(μ-S)3.SbCl3][S2P(OEt)2]3[SXP(OEt)2].(C3H3ON)}(X=S,O)的晶体结构。结构测定结果表明,这两个加合物的分子由{Mo3(μ3-S)(μ-S)3[S2P(OEt)2]4.L(L=C2H5OH,C3H3ON)通过三个(μ-S)联结SbCl3而成,从而获得了{Mo3SbS4}的类立方烷簇胳构型,Sb一S之间存在较弱的配位键, 由此推断,若加合的金属原子的轨道和电子组态适宜,有可能通过这种[3+1]的成簇模式获得四核的同核或异核簇合物。     

Bonding, structure, and energetics of gaseous E8(2+) and of solid E8(AsF6)2 (E = S, Se)

The attempt to prepare hitherto unknown homopolyatomic cations of sulfur by the reaction of elemental sulfur with blue S8(AsF6)2 in liquid SO2/SO2ClF, led to red (in transmitted light) crystals identified crystallographically as S8(AsF6)2. The X-ray structure of this salt was redetermined with improved resolution and corrected for librational motion: monoclinic, space group P2(1)/c (No. 14), Z = 8, a = 14.986(2) A, b = 13.396(2) A, c = 16.351(2) A, beta = 108.12(1) degrees. The gas phase structures of E8(2+) and neutral E8 (E = S, Se) were examined by ab initio methods (B3PW91, MPW1PW91) leading to delta fH theta[S8(2+), g] = 2151 kJ/mol and delta fH theta[Se8(2+), g] = 2071 kJ/mol. The observed solid state structures of S8(2+) and Se8(2+) with the unusually long transannular bonds of 2.8-2.9 A were reproduced computationally for the first time, and the E8(2+) dications were shown to be unstable toward all stoichiometrically possible dissociation products En+ and/or E4(2+) [n = 2-7, exothermic by 21-207 kJ/mol (E = S), 6-151 kJ/mol (E = Se)]. Lattice potential energies of the hexafluoroarsenate salts of the latter cations were estimated showing that S8(AsF6)2 [Se8(AsF6)2] is lattice stabilized in the solid state relative to the corresponding AsF6- salts of the stoichiometrically possible dissociation products by at least 116 [204] kJ/mol. The fluoride ion affinity of AsF5(g) was calculated to be 430.5 +/- 5.5 kJ/mol [average B3PW91 and MPW1PW91 with the 6-311 + G(3df) basis set]. The experimental and calculated FT-Raman spectra of E8(AsF6)2 are in good agreement and show the presence of a cross ring vibration with an experimental (calculated, scaled) stretching frequency of 282 (292) cm-1 for S8(2+) and 130 (133) cm-1 for Se8(2+). An atoms in molecules analysis (AIM) of E8(2+) (E = S, Se) gave eight bond critical points between ring atoms and a ninth transannular (E3-E7) bond critical point, as well as three ring and one cage critical points. The cage bonding was supported by a natural bond orbital (NBO) analysis which showed, in addition to the E8 sigma-bonded framework, weak pi bonding around the ring as well as numerous other weak interactions, the strongest of which is the weak transannular E3-E7 [2.86 A (S8(2+), 2.91 A (Se8(2+)] bond. The positive charge is delocalized over all atoms, decreasing the Coulombic repulsion between positively charged atoms relative to that in the less stable S8-like exo-exo E8(2+) isomer. The overall geometry was accounted for by the Wade-Mingos rules, further supporting the case for cage bonding. The bonding in Te8(2+) is similar, but with a stronger transannular E3-E7 (E = Te) bonding. The bonding in E8(2+) (E = S, Se, Te) can also be understood in terms of a sigma-bonded E8 framework with additional bonding and charge delocalization occurring by a combination of transannular n pi *-n pi * (n = 3, 4, 5), and np2-->n sigma * bonding. The classically bonded S8(2+) (Se8(2+) dication containing a short transannular S(+)-S+ (Se(+)-Se+) bond of 2.20 (2.57) A is 29 (6) kJ/mol higher in energy than the observed structure in which the positive charge is delocalized over all eight chalcogen atoms.     

Enantiospecific synthesis of (6R,7S,8aR)-dihydroxyindolizidine and (6R,7R,8S,8aR)-trihydroxyindolizidine from D-glucose.

Enantiospecific syntheses of (6R,7S,8aR)-dihydroxyindolizidine (1) and (6R,7R,8S,8aR)-trihydroxyindolizidine (2) from readily available methyl 2-azido-4,6-O-benzylidene-2-deoxy-α-D-altropyranoside (5) are described.     

Total synthesis of (4R,5S,6E,14S)- and (4R,5S,6E,14R)-cystothiazoles F

Total synthesis of (4R,5S,6E,14S)- and (4R,5S,6E,14R)-cystothiazoles F 3 was achieved from the chiral bithiazole-type primary alcohols [(S)- and (R)-4-ethoxycarbonyl-2′-(1-hydroxymethylethyl)-2,4′-bithiazoles 8], which were obtained based on the enzymatic resolution of racemic alcohol 8 and its acetate 9. From a direct comparison by means of chiral HPLC between natural cystothiazole F 3 and synthetic compounds [(4R,5S,6E,14S)- and (4R,5S,6E,14R)-cystothiazoles 3], natural cystothiazole F 3 was found to be a 33:67 diastereomeric mixture [(4R,5S,6E,14S)-3:(4R,5S,6E,14R)-3 = 33:67].     

Total synthesis of (-)-(6S,7S,8S,9R,10S,2'S)-membrenone-A and (-)-(6S,7S,8S,9R,10S)- membrenone-B and structural assignment of membrenone-C

[reaction: see text] (-)-(6S,7S,8S,9R,10S,2'S)-Membrenone-A and (-)-(6S,7S,8S,9R,10S)-membrenone-B were prepared in 11 steps (3% and 2.4% overall yield, respectively). Key steps included a tin(II)-mediated aldol followed by a syn selective reduction, giving the C7-C9 stereocenters, a second chain extending aldol coupling, and a p-TsOH-promoted cyclization/dehydration giving the common gamma-dihydropyrone precursor. We have thus established that synthetic (-)-(6S,7S,8S,9R,10S,2'S)-membrenone-A, (-)-(6S,7S,8S,9R,10S)-membrenone-B, and (-)-(6S,7S,8S,9R,10S)-membrenone-C are the enantiomers of the natural products.     

Synthesis of (2S, 3S, 4E, 6E)-3-O-β-D-galactopyranosyl-2-N-hexadecanoyl-8-oxo-4,6-sphingadienine pentaacetate

Institute of Organic Chemistry, Ural Branch, Russian Academy of Sciences, 450054 Ufa. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 5, pp. 1226–1227, May, 1992.     

Synthesis and modeling study of (2S,5R,6R)- and (2S,5R,6S)-6-hydroxy- 8-(1-decynyl)-benzolactam-V8 as protein kinase C modulators

[structures: see text] Both (2S,5R,6R)- and (2S,5R,6S)-6-hydroxy-8-(1-decynyl)benzolactam-V8 were designed and synthesized as PKC modulators. Biological assays reveal the (6R)-ligand to be 20-fold more potent than its (6S)-counterpart in binding to PKC alpha.