Synthesis and structure of a novel MoFe4S4 cubane-like cluster (Me3PhCH2N)2 [MoFe4S4 (SC6H11)7]

A novel (Me₃PhCH₂N)₂[MoFe₄S₄(SC₆H₁₁)₇] cubane-like cluster was obtained from a reaction system including (NH₄)₂MoS₄, FeCl₂ and NaSC₆H₁₁ in methanol, and characterized by X-ray crystallography. The title compound crystallizes in triclinic space group witha = 1.523 1(3), b =1.610 5(3),c = 1.838 3(4) nm, α = 77.18 (3)°, β = 75.17(3)°, γ = 64.60(3)°, and Z = 2. Also included in this paper are the discussions on the variation of the reaction products obtained from the participation of cyclohexylthiolate and on the changes of the structural features of the products. Project supported by the National Natural Science Foundation of China and the Climbing Program—State Key Project for Fundamental Research in China, and Hong Kong Research Grants Council (Earmarked Grant No. CUHK. 311/94p).     

MoFe3S4单立方烷原子簇研究II. MoFe3S4(C5H10NCSS)5的合成与结构

六氢吡啶基二硫代甲酸钠盐、氯化亚铁及四硫代钼酸铵在二甲基甲酰胺及二氯甲烷中,经一步自兜反应,分别得到了[MoFe3S4(C5H10NCSS)5]DMF及[MoFe3S4(C5H10NCSS)5]CH2Cl2.通过X射线衍射测定了后者的晶体结构,比较了它与[MoFe3S4(Et2NCSS)5]^-结构特点的异同,同时研究了反应物摩尔比对产物的影响以及溶剂分子的置换反应.     

MoFe3单立方烷原子簇研究I.(Et~4N)[MoFe~3S~4(Et~2NCSS)~5]CH~3CN的自兜合成及结构

双齿含硫配位体,二乙胺基二硫代甲酸钠盐与氯化亚铁及四硫代钼酸铵在二甲基甲酰胺溶液中,经一步自兜反应得到(Et~4N)[MoFe~3S~4(Et~2NCSS)~5]CH~3CN(1).X射线单晶结构测定表明1具有类立方烷骨架,核心价态为[MoFe~3S~4]^4^+,通过对1的阴离子结构分析,指出配位基的双齿螯合作用对化合物的稳定性及结构的影响。化学键理论计算也解释了阴离子中的主要键长特点。     

Synthesis and electrochemistry of phenyl-functionalized diiron propanedithiolate complexes with bidentate phosphine ligands

Carbonyl substitution reactions of [μ-(SCH₂)₂CHC₆H₅]Fe₂(CO)₆ with bidentate phosphine ligands, cis-1,2-bis(diphenylphosphine)ethylene (cis-dppv) and N,N-bis(diphenylphosphine)propylamine [(Ph₂P)₂N-Pr-n], yielded an asymmetrically substituted chelated complex [(μ-SCH₂)₂CHC₆H₅]Fe₂(CO)₄(k ²-dppv) and a symmetrically substituted bridging complex [(μ-SCH₂)₂CHC₆H₅]Fe₂(CO)₄[μ-(PPh₂)₂N-Pr-n] under different reaction conditions. Both complexes were fully characterized by spectroscopic methods and by X-ray crystallography. Their electrochemical behaviors were observed by cyclic voltammetry, and the catalytic electrochemical reduction of protons from acetic or trifluoroacetic acid to give dihydrogen mediated by complex [(μ-SCH₂)₂CHC₆H₅]Fe₂(CO)₄(k ²-dppv) was investigated.     

Borohydride, azide, and chloride anions as terminal ligands on Fe/Mo/S clusters. Synthesis, structure and characterization of [(Cl4-cat)(PPr3) MoFe3S4(X)2]2(Bu4N)4 and [(Cl4-cat)(PPr3)MoFe3S4 (PPr3)(X)]2(Bu4N)2 (X = N3-, BH4-, Cl-) double-fused cubanes. NMR reactivity studies of [(Cl4-cat)(PPr3) MoFe3S4(BH4)2]2(Bu4N)4

Our explorations of the reactivity of Fe/Mo/S clusters of some relevance to the FeMoco nitrogenase have led to new double-fused cubane clusters with the Mo2Fe6S8 core as derivatives of the known (Cl4-cat)2Mo2Fe6S8(PPr3)6 (I) fused double cubane. The new clusters have been obtained by substitution reactions of the PPr3 ligands with Cl-, BH4-, and N3-. By careful control of the conditions of these reactions, the clusters [(Cl4-cat)(PPr3)MoFe3S4(BH4)2]2(Bu4N)4 (II), [(Cl4-cat)(PPr3)MoFe3S4(PPr3)(BH4)]2(Bu4N)2 (III), [(Cl4-cat)(PPr3)MoFe3S4(N3)2]2(Bu4N)4 (IV), [(Cl4-cat)(PPr3)MoFe3S4(PPr3)(N3)]2(Bu4N)2 (V), and [(Cl4-cat)(PPr3)MoFe3S4Cl2]2(Et4N)4 (VI) have been obtained and structurally characterized. A study of their electrochemistry shows that the reduction potentials for the derivatives of I are shifted to more positive values than those of I, suggesting a stabilization of the reduced clusters by the anionic ligands BH4- and N3-. Using 1H NMR spectroscopy, we have explored the lability of the BH4- ligand in II in coordinating solvents and its hydridic character, which is apparent in its reactivity toward proton sources such as MeOH or PhOH.     

Synthesis and characterization of sulfur-voided cubanes. Structural analogues for the MoFe(3)S(3) subunit in the nitrogenase cofactor.

A new class of Mo/Fe/S clusters with the MoFe(3)S(3) core has been synthesized in attempts to model the FeMo-cofactor in nitrogenase. These clusters are obtained in reactions of the (Cl(4)-cat)(2)Mo(2)Fe(6)S(8)(PR(3))(6) [R = Et (I), (n)Pr (II)] clusters with CO. The new clusters include those preliminarily reported: (Cl(4)-cat)MoFe(3)S(3)(PEt(3))(2)(CO)(6) (III), (Cl(4)-cat)(O)MoFe(3)S(3)(PEt(3))(3)(CO)(5) (IV), (Cl(4)-cat)(Pyr)MoFe(3)S(3)(PEt(3))(2)(CO)(6) (VI), and (Cl(4)-cat)(Pyr)MoFe(3)S(3)(P(n)Pr(3))(3)(CO)(4) (VIII). In addition the new (Cl(4)-cat)(O)MoFe(3)S(3)(P(n)Pr(3))(3)(CO)(5) cluster (IVa), the (Cl(4)-cat)(O)MoFe(3)S(3)(PEt(3))(2)(CO)(6)cluster (V), the (Cl(4)-cat)(O)MoFe(3)S(3)(P(n)Pr(3))(2)(CO)(6) cluster (Va), the (Cl(4)-cat)(Pyr)MoFe(3)S(3)(P(n)Pr(3))(2)(CO)(6) cluster (VIa), and the (Cl(4)-cat)(P(n)Pr(3))MoFe(3)S(3)(P(n)Pr(3))(2)(CO)(6) cluster (VII) also are reported. Clusters III-VIII have been structurally and spectroscopically characterized. EPR, zero-field (57)Fe-M?ssbauer spectroscopic characterizations, and magnetic susceptibility measurements have been used for a tentative assignment of the electronic and oxidation states of the MoFe(3)S(3) sulfur-voided cuboidal clusters. A structural comparison of the clusters with the MoFe(3)S(3) subunit of the FeMo-cofactor has led to the suggestion that the storage of reducing equivalents into M-M bonds, and their use in the reduction of substrates, may occur with the FeMo-cofactor, which also appears to have M-M bonding. On the basis of this argument, a possible N(2)-binding and reduction mechanism on the FeMoco-cofactor is proposed.     

[MoFe3S4]3+ and [MoFe3S4]2+ cubane clusters containing a pentamethylcyclopentadienyl molybdenum moiety

A series of organometallic molybdenum/iron/sulfur clusters of the general formula [Cp¹MoFe₃S₄L_n]^m (Cp¹ = η⁵-C₅Me₅; L = S^tBu, SPh, Cl, I, n = 3, m = 1−; L_n = I₂(P^tBu₃), m = 0; L = 2,6-diisopropylphenylisocyanide (ArNC), n = 7, m = 1+) have been synthesized. A cubane cluster (PPh₄)[Cp¹MoFe₃S₄(S^tBu)₃] (2) was isolated from a self-assembly reaction of Cp¹Mo(S^tBu)₃ (1), FeCl₃, LiS^tBu, and S₈ followed by cation exchange with PPh₄Br in CH₃CN, while an analogous cluster (PPh₄)[Cp¹MoFe₃S₄(SPh)₃] (3) was obtained from the Cp¹MoCl₄/FeCl₃/LiSPh/PPh₄Br reaction system or from a ligand substitution reaction of 2 with PhSH. Treatment of 2 with benzoyl chloride gave rise to (PPh₄)[Cp¹MoFe₃S₄Cl₃] (4), which was in turn converted to (PPh₄)[Cp¹MoFe₃S₄I₃] (5) by the reaction with NaI. A neutral cubane cluster Cp¹MoFe₃S₄I₂(P^tBu₃) (6) was generated upon treating 5 with P^tBu₃. Although reduction of 4 by cobaltocene under the presence of ArNC resulted in a disproportionation of the cubane core to give Fe₄S₄(ArNC)₉Cl (7), a similar reduction reaction of 5 produced [Cp¹MoFe₃S₄(ArNC)₇]I (8), where the MoFe₃S₄ core was retained. The crystal structures of 4–6, and 8 were determined by the X-ray analysis.     

Enhanced lasing properties of dissymmetric Eu(III) complex with bidentate phosphine ligands

The luminescent and lasing properties of Eu(III) complexes were enhanced by using an dissymmetric Eu(III) complex. The photophysical properties (the emission spectral shapes, the emission lifetimes, the emission quantum yields, and the stimulated emission cross section (SEC)) were found to be dependent on the geometrical structures of Eu(III) complexes. The geometrical structures of Eu(III) complexes were determined by X-ray single crystal analyses. The symmetrical group of Eu(hfa)3(BIPHEPO) (tris(hexafluoroacetylacetonato)europium(III) 1,1'-biphenyl-2,2'-diylbis(diphenylphosphine oxide)) was found to be C1, which was more dissymmetric than Eu(hfa)3(TPPO)2 (tris(hexafluoroacetylacetonato)europium(III) 1,2-phenylenebis(diphenylphosphine oxide): C2 symmetry) and Eu(hfa)3(OPPO)2 (tris(hexafluoroacetylacetonato)europium(III) 1,2-phenylenebis(diphenylphosphine oxide): C2 symmetry). The analytical data were supported by Judd-Ofelt analysis. The most dissymmetrical Eu(III) complex, Eu(hfa)3(BIPHEPO), showed large electron transition probability and large SEC (4.64 x 10(-20) cm2). The SEC of Eu(hfa)3(BIPHEPO) was superior to even the values of Nd-glass laser for practical use (1.6-4.5 x 10(-20) cm2). The lasing properties of Eu(III) complexes in polymer thin film were measured by photopumping of a Nd:YAG laser (355 nm). The threshold energy of lasing oscillation was found to be 0.05 mJ. The increasing rate of the lasing intensity of Eu(hfa)3(BIPHEPO) as a function of the excitation energy was much larger than that of Eu(hfa)3(TPPO)2 and Eu(hfa)3(OPPO)2. The dissymmetrical structure of Eu(hfa)3(BIPHEPO) promoted the enhancement of the lasing property.     

Di and monocarbonyl complexes of rhodium(I) containing singly charged bidentate ligands

Summary A series of neutral square planar rhodium(I) dicarbonyls containing singly charged bidentate ligands (salicylaldoxime, -benzoinoxime, -furildioxime, -benzildioxime, dimethylglyoxime, cupferron) has been prepared from three sources: (i) tetracarbonyl--dichlorodirhodium(I), (ii) solutions of hydrated rhodium chloride in DMF held under reflux and (iii) a carbonylated solution of hydrated rhodium chloride in boiling absolute alcohol. These dicarbonyls react with triphenylphosphine,-arsine and -stibine to yield monocarbonyl derivatives. The monocarbonyls form 1 : 1 adducts with TCNE. All complexes have been characterized by elemental analysis, i.r. and uv-visible spectra.     

Rhodium(I) phosphine complexes containing bidentate unsaturated thio ligands: I. Synthesis and characterisation

The rhodium(I) complexes (Ph₃P)₂Rh(LL′), in which LL′ is an unsaturated chelate coordinating via L = S and L′ = N, O, P or S, have been prepared from RhCl(PPh₃)₃ by two routes.Direct substitution of one Ph₃P and Cl^? by the chelate anion gives (Ph₃P)₂Rh[Ph₂PC(S)S] (L = S, L′ = P). Oxidative addition of an NH bond followed by reductive elimination of HCl results in (Ph₃P)₂Rh[Me₂NC(S)NC(S)NMe₂] (L = S, L′ = S), (Ph₃P)₂Rh[PhNC(S)NMe₂] (L = S, L′ = N), (Ph₃P)₂Rh[Ph₂PC(S)NPh) (L = S, L′ = P) and (Ph₃P)₂Rh[Ph₂P(O)C(S)NPh] (L = S, L′ = O).Reaction of the complexes (Ph₃P)₂Rh(LL′) with CO gives (CO)(Ph₃P)Rh(LL′) with CO trans to the chelate donor atom with the lowest trans-influence. Pt(PPh₃)₄ reacts with Me₂NC(S)N(H)C(S)NMe₂ and HN(Ph)C(S)PPh₂, respectively, to give H(Ph₃P)Pt[Me₂NC(S)NC(S)NMe₂] (L = S, L′ = S) and H(Ph₃P)Pt[Ph₂PC(S)NPh] (L = S, L′ = P).The coordinating atoms and their configurations have been assigned by IR ³¹P NMR and ¹H NMR. Some trend in IR and ³¹P NMR paramaters are discussed.     

Investigation of single MoFe3S4 cubane cluster: I. First successful synthesis by spontaneous self-assembly reaction and structure of (Et4N) [MoFe3S4(Et2NCSS)5]CH3CN

A single MoFe₃S₄ cubane-like cluster compound has been synthesized through spontaneous self-assembly of simple inorganic salts with organosulfur ligand for the first time. (Et₄N)-(MoFe₃S₄(Et₂NCSS)₅] CH₃CN(1) is quite stable in air. The crystal of 1 is monoclinic with space group P2/c, a=22.897 (3)Å, b= 12.399 (2)Å, c=20.928 (4)Å, β=97.15 (1)°, and Z=4. A full matrix least-squares refinement with 6725 unique reflections for all nonhydrogen atoms gives R=0.068. The anion of 1 is the first isolated single MoFe₃S₄ cubane cluster with core oxidation state [MoFe₃S₄]⁴⁺. The distance between the two 6-coordinate metal atoms (Mo, Fe) is 2.624 Å, which is the shortest M-M' bond observed for Mo-Fe-S clusters so far and the only one shorter than similar distances in FeMo-cofactor. The bond orders of this anion were calculated by EHMO method and the results coincide with the general rule. The structural feature and the unusual stability of 1 can be attributed to the bidentate chelating effect of Et₂NCSS-, which leads to high coordination of metal atoms and the various ligated types.     

Synthesis and characterization of triorganoantimony(V) complexes with bidentate ligands

Monochelated organoantimony(V) complexes of the type R₃Sb(OMe)L, where R = Me or Ph, and L is the anion of acetylacetone, 8-hydroxyquinoline, salicylaldehyde, o-hydroxyacetophenone or 2-hydroxy-1-naphthaldehyde have been obtained from triorganoantimony(V) dibromide and the sodium derivative of the ligands in a benzene-methanol mixture. Molecular weight determination in benzene reveals the monomeric nature of these complexes. IR and NMR data suggest that L acts as a bidentate ligand giving an octahedral environment for the antimony atom.     

Synthesis of [SCo3(CO)7(S2COMe)] and the structure of its PPh3 derivative

Summary The title compound has been prepared in reasonable yield by reaction of a methanolic solution of CoCl₂ and MeOCS₂K with CO. I.r. spectra have been analyzed both in the C-O stretching region and in the region of the main vibrations of the xanthate ligand: an explanation of the appearance of only 4 out of 7 i.r.-active (CO) modes is proposed. The structure of the triphenylphosphine derivative has been solved by x-ray diffraction analysis: [SCo₃(CO)₆(PPh₃)(S₂COMe)] crystallizes in the triclinic space group P¯1, witha = 10.710(3),b = 10.199(3) andc = 16.208(4) Å, = 113.57(2)°, = 98.14(2)°, = 104.32(2)°, Z = 2, (MoK) = 0.7107 Å. The final R value is 0.045 [4461 reflections with F > 6 (F)]. The molecule is formed by an SCo₃ cluster, in which each Co atom coordinates two CO groups. The chelating xanthate ligand is equatorially bonded to two cobalt atoms forming a nonplanar pentaatomic ring; the phosphine is equatorially bonded to the other cobalt atom.     

Borohydride anions as terminal ligands on a Fe/Mo/S cluster. Synthesis, structure, and characterization of the [(Cl4-cat)(PPr3)MoFe3S4(BH4)2]2(Bu4N)4 double-fused cubane

The synthesis and structure of the first Mo/Fe/S/BH(4) cluster is reported. Reaction of (Cl(4)-cat)(2)Mo(2)Fe(6)S(8)(PPr(3))(6) with 4 equiv of Bu(4)NBH(4) results in the formation of [(Cl(4)-cat)(PPr(3))MoFe(3)S(4)(BH(4))(2)](2)(Bu(4)N)(4) (Cl(4)-cat = tetrachloro-catecholate) which has been fully characterized. X-ray structural determination of this double-fused cubane reveals four BH(4)(-) ligands bound to four Fe atoms in a bidentate fashion. A synopsis of the solution characterization as well as the reactivity of this cluster is also presented.     

Synthesis and Characterization of MoFe3S4 and Mo2Fe2S4 Single Cubanes

The synthesis of multimetallic M/S clusters by the reductive coupling of dimeric building blocks appears to be of general utility. In this paper we describe the synthesis and characterization of new single cubanes with cores such as [Mo₂Fe₂S₄]²⁺ and [MoFe₃S₄]^3+,2+.     

Synthesis and characterisation of nonclassical ruthenium hydride complexes containing chelating bidentate and tridentate phosphine ligands

The synthesis and characterisation of nonclassical ruthenium hydride complexes containing bidentate PP and tridentate PCP and PNP pincer-type ligands are described. The mononuclear and dinuclear ruthenium complexes presented have been synthesised in moderate to high yields by the direct hydrogenation route (one-pot synthesis) or in a two-step procedure. In both cases [Ru(cod)(metallyl)(2)] served as a readily available precursor. The influences of the coordination geometry and the ligand framework on the structure, binding, and chemical properties of the M--H(2) fragments were studied by X-ray crystal structure analysis, spectroscopic methods, and reactivity towards N(2), D(2), and deuterated solvents.     

铁铂硫原子簇化合物的合成与结构研究 V: [MoFe3S4]类立方烷簇合物的转化反应和[Et4N]3[Mo2Fe6S8(SC6H4CH3-m)3Cl6]的晶体结构

具[MoFe2S4]类立方烷结构单元的双类立方烷化合物[Et4N]4[Mo2Fe7S8(SR)12](1a,R=Ph; 1b, R=tolyl-m)或单类立方烷化合物[MoFe3S4(dteR2)5](2a, R=Me; 2b, R=Et)与酰氯在乙腈中反应, 分别得到不含Fe桥的双类立方烷化合物(Et4N)3[Mo2Fe6S8(SR)3Cl6](3a, R=Ph; 3b, R=toly-m)与[MoFe3S4]骨架支解后的Fe(dteR2)2Cl(4a, R=Me; 4b, R=Et)。说明在相同反应条件下, [MoFe3S4]单元在1中比在2中稳定, 本文首次将1型与3型结构通过一步化学反应连系起来。3型化合物的产生得到X射线衍射测定及^1H NMR谱的证实。本文报道3b的单晶结构及3的^!H NMR数据, 3b属六方晶系, P63/m, a=1.6827(3), c=1.5951(16)nm; V=3.91158nm^3; Dc=1.491g/cm^3;Z=2; F(000)=1780; 偏离因子R=0.048, 化合物2与酰氯反应产生4, 由红外及紫外可见光谱证实。     

双(二苯基膦)烷烃的合成与表征

以三苯基膦为起始原料,四氢呋喃为溶剂,经过金属锂化与烷基化分别合成了1,1-双二苯基膦甲烷(DPPM)、1,2-双二苯基膦乙烷(DPPE)、1,3-双二苯基膦丙烷(DPPP)、1,4-双二苯基膦丁烷(DPPB)、1,5-双二苯基膦戊烷(DPPPe)和1,6-双二苯基膦己烷(DPPH),收率为75%~86%.通过1 H NMR、31 P NMR、MS和元素分析确证了目标化合物的结构.