A heterobimetallic complex with an unsupported uranium(III)-aluminum(I) bond: (CpSiMe3)3U-AlCp* (Cp* = C5Me5)

A heterobimetallic complex with the first unsupported bond between an actinide and a group 13 element, (CpSiMe3)3U-AlCp* (Cp* = C5Me5) (1), was synthesized by reaction of (CpSiMe3)3U and 1/4(Cp*Al)4 in toluene. Density functional theory calculations indicate that the U-Al bond exhibits some covalent character resulting from a Cp*Al-->U charge-transfer.     

Divalent dirhodium imido complexes: formation, structure, and alkyne cycloaddition reactivity

Dirhodium amido complexes [(Cp*Rh)2(mu2-NHPh)(mu2-X)] (X = NHPh (2), Cl (3), OMe (4); Cp* = eta5-C5Me5) were prepared by chloride displacement of [Cp*Rh(mu2-Cl)]2 (1) and have been used as precursors to a dirhodium imido species [Cp*Rh(mu2-NPh)RhCp*]. The imido species can be trapped by PMe3 to give the adduct [Cp*Rh(mu2-NPh)Rh(PMe3)Cp*] (5) and undergoes a formal [2 + 2] cycloaddition reaction with unactivated alkynes to give the azametallacycles [Cp*Rh(mu2-eta2:eta3-R1CCR2NPh)RhCp*] (R1 = R2 = Ph (6a), R1 = H, R2 = t-Bu (6b), R1 = H, R2 = p-tol (6c)). Isolation of a relevant unsaturated imido complex [Cp*Rh(mu2-NAr)RhCp*] (7) was achieved by the use of a sterically hindered LiNHAr (Ar = 2,6-diisopropylphenyl) reagent in a metathesis reaction with 1. X-ray structures of 2, 6a, 7 and the terminal isocyanide adduct [Cp*Rh(mu2-NAr)Rh(t-BuNC)Cp*] (8) are reported.     

Role of the transition metal in metallaborane chemistry. Reactivity of (Cp*ReH2)2B4H4 with BH3.thf, CO, and Co2(CO)8

The reaction of Cp*ReCl4, [Cp*ReCl3]2, or [Cp*ReCl2]2 (Cp* = eta 5-C5Me5) with LiBH4 leads to the formation of 7-skeletal-electron-pair (7-sep) (Cp*ReH2)2(B2H3)2 (1) together with Cp*ReH6. Compound 1 is metastable and eliminates H2 at room temperature to generate 6-sep (Cp*ReH2)2B4H4 (2). The reaction of 2 with BH3.thf produces 7-sep (Cp*Re)2B7H7, a hypoelectronic cluster characterized previously. Heating of 2 with 1 atm of CO leads to 6-sep (Cp*ReCO)(Cp*ReH2)B4H4 (3). Both 2 and 3 have the same bicapped Re2B2 tetrahedral cluster core structure. Monitoring the reaction of 2 with CO at room temperature by NMR reveals the formation of a 7-sep, metastable intermediate, (Cp*ReCO)(Cp*ReH2)(B2H3)2 (4), which converts to 3 on heating. An X-ray structure determination reveals two isomeric forms (4-cis and 4-trans) in the crystallographic asymmetric unit which differ in geometry relative to the disposition of the metal ancillary ligands with respect to the Re-Re bond. The presence of these isomers in solution is corroborated by the solution NMR data and the infrared spectrum. In both isomers, the metallaborane core consists of fused B2Re2 tetrahedra sharing the Re2 fragment. On the basis of similarities in electron count and spectroscopic data, 1 also possesses the same bitetrahedral structure. The reaction of 2 with CO2(CO)8 results in the formal replacement of the four rhenium hydrides with a 4-electron CO2(CO)5 fragment, thereby closing the open face in 2 to produce the 6-sep hypoelectronic cluster (Cp*Re)2CO2(CO)5B4H4 (5). These reaction outcomes are compared and contrasted with those previously observed for 5-sep (Cp*Cr2)2B4H8.     

Different C-C coupling reactions of permethyltitanocene and permethylzirconocene with disubstituted 1,3-butadiynes

Herein we describe different C-C coupling reactions of permethyltitanocene and -zirconocene with disubstituted 1,3-butadiynes. The outcomes of these reactions vary depending on the metals and the diyne substituents. The reduction of [Cp2*MCl2] (Cp* = C5Me5; M = Ti, Zr) with Mg in the presence of disubstituted butadiynes RC triple bond C-C triple bond CR' is suitable for the synthesis of different C-C coupling products of the diyne and the permethylmetallocenes, and provides a new method for the generation of functionalized pentamethyl-cyclopentadienyl derivatives. For M = Zr and R = R' = tBu, the reaction gives, by a twofold activation of one pentamethylcyclopentadienyl ligand, the complex [Cp*Zr[-C(=C=CHtBu)-CHtBu-CH2-eta5-C5Me3-CH2-]] (3), containing a fulvene ligand that is coupled to the modified substrate (allenic subunit). When using the analogous permethyltitanocene fragment "Cp2*Ti", the reaction depends strongly on the substituents R and R'. The coupling product of the butadiyne with two methyl groups of one of the pentamethylcyclopentadienyl ring systems, [Cp*Ti[eta5-C5Me3-(CH2-CHR-eta2-C2-CHR'-CH2)]], is obtained with R = R' = tBu (4) and R = tBu, R' = SiMe3 (5). In these complexes one pentamethylcyclopentadienyl ligand is annellated to an eight-membered ring with a C-C triple bond, which is coordinated to the titanium center. A different activation of both pentamethylcyclopentadienyl ligands is observed for R = R' = Me, resulting in the complex [[eta5-C5Me4(CH2)-]Ti[-C(=CHMe)-C(=CHMe)-CH2-eta5-C5Me4]] (6), which displays a fulvene as well as a butadienyl-substituted pentamethylcyclopentadienyl ligand. The influence exerted by the size of the metal is illustrated in the reaction of [Cp2*ZrCl2] with MeC triple bond C-C triple bond CMe. Here the five-membered metallacyclocumulene complex [Cp2*Zr(eta4-1,2,3,4-MeC4Me)] (7) is obtained. The reaction paths found for R = R' = Me are identical to those formerly described for R = R' = Ph.     

Structure of the decamethyl titanocene cation,a metallocene with two agostic C-h bonds,and its interaction with fluorocarbons

The tetraphenylborate salt of the decamethyl titanocene cation, [Cp*2Ti][BPh4] (1, Cp* = C5Me5), was prepared by reaction of Cp*2TiH with [Cp2Fe][BPh4] and by reaction of Cp*2TiMe with [PhNMe2H][BPh4]. The crystal structure of 1 shows that the Cp*2Ti cation has a bent metallocene structure with agostic interactions with the metal center of two adjacent methyl groups on one of the Cp* ligands. Compound 1 reacts readily with THF to give the adduct [Cp*2Ti(THF)][BPh4] (2). In fluorobenzene, 1 forms the eta1-fluorobenzene adduct [Cp*2Ti(eta1-FC6H5)][BPh4] (3), which was structurally characterized. In contrast to the thermal stability of 3, addition of alpha,alpha,alpha-trifluorotoluene to either 1 or 2 results in C-F activation to give Cp*2TiF2 and PhCF2CF2Ph as the main products. This reactivity toward benzylic C-F bonds is also reflected in the reactivity toward the fluorinated borate anions [B(C6F5)4]- and {B(3,5-(CF3)2C6H3]4}-: reaction of Cp*2TiMe with their [PhNMe2H]+ salts results in a stable complex for the former anion, whereas rapid C-F activation is observed for the latter.     

Increased reactivity of the *Cr(CO)3(C5Me5) radical with thiones versus thiols: a theoretical and experimental investigation

2-pyridinethione (2-mercaptopyridine, H-2mp) undergoes rapid oxidative addition with 2 mol of the 17-electron organometallic radical *Cr(CO)3Cp (where Cp*=C5Me5), yielding hydride H-Cr(CO)3Cp* and thiolate (eta1-2mp)Cr(CO)3Cp*. In a slower secondary reaction, (eta1-2mp)Cr(CO)3Cp* loses CO generating the N,S-chelate complex (eta2-2mp)Cr(CO)2Cp* for which the crystal structure is reported. The rate of 2-pyridine thione oxidative addition with *Cr(CO)3Cp* (abbreviated *Cr) in toluene best fits rate=kobs[H-2mp][*Cr]; kobs(288 K)=22 +/- 4 M(-1) s(-1); DeltaH++=4 +/- 1 kcal/mol; DeltaS++=- 40 +/- 5 cal/mol K. The rate of reaction is the same under CO or Ar, and the reaction of deuterated 2-pyridine thione (D-2mp) shows a negligible (inverse) kinetic isotope effect (kD/kH=1.06 +/- 0.10). The rate of decarbonylation of (eta1-2mp)Cr(CO)3Cp* forming (eta2-2mp)Cr(CO)2Cp* obeys simple first-order kinetics with kobs (288 K)=3.1x10(-4) s(-1), DeltaH++=23 +/- 1 kcal/mol, and DeltaS++=+ 5.0 +/- 2 cal/mol K. Reaction of 4-pyridine thione (4-mercaptopyridine, H-4mp) with *Cr(CO)3Cp* in THF and CH2Cl2 also follows second-order kinetics and is approximately 2-5 times faster than H-2mp in the same solvents. The relatively rapid nature of the thione versus thiol reactions is attributed to differences in the proposed 19-electron intermediate complexes, [*(S=C5H4N-H)Cr(CO)3Cp*] versus [*(H-S-C6H5)Cr(CO)3Cp*]. In comparison, reactions of pyridyl disulfides occur by a mechanism similar to that followed by aryl disulfides involving direct attack of the sulfur-sulfur bond by the metal radical. Calorimetric data indicate Cr-SR bond strengths for aryl and pyridyl derivatives are similar. The experimental conclusions are supported by B3LYP/6-311+G(3df,2p) calculations, which also provide additional insight into the reaction pathways open to the thione/thiol tautomers. For example, the reaction between H* radical and the 2-pyridine thione S atom yielding a thionyl radical is exothermic by approximately 30 kcal/mol. In contrast, the thiuranyl radical formed from the addition of H* to the 2-pyridine thiol S atom is predicted to be unstable, eliminating either H* or HS* without barrier.     

Reactivity of amido ligands on a dinuclear Ru(II) center: formation of imido complexes and C-N coupling reaction with alkyne

Treatment of a dinuclear Ru(II) amido complex [Cp*Ru(mu2-NHPh)]2 (Cp* = eta5-C5Me5) with small organic substrates including CO, tert-butyl isocyanide, a sulfur ylide Ph2S=CH2, and diphenylacetylene resulted in an unexpected disproportionation reaction of the bridging amido ligands to produce a free amine and a series of imido-bridged diruthenium complexes [(Cp*Ru)2(mu2-L)(mu2-NPh)] (L = CO, t-BuNC, CH2). In the case of diphenylacetylene, the bridging imido ligand underwent subsequent coupling reaction with the coordinated alkyne to form an iminoalkenyl complex [(Cp*Ru)2(mu2-PhNCPhCPh)].     

Uranium(III)/(IV) nitrile adducts including UI4(N[triple bond]CPh)4, a synthetically useful uranium(IV) complex

The synthesis of complexes used to elucidate an understanding of fundamental An(III) and An(IV) coordination chemistry requires the development of suitable organic-soluble precursors. The reaction of oxide-free uranium metal turnings with 1.3 equivalents of elemental iodine in acetonitrile provided the U(III)/U(IV) complex salt, [U(N[triple bond]CMe)9][UI6][I] (1), in which the U(III) cation is surrounded by nine acetonitrile molecules in a tricapped trigonal prismatic arrangement, a [UI6]2- counterion, and a noncoordinating iodide. The U-N distances for the prismatic and capping nitrogens are 2.55(3) and 2.71(5) A, respectively. The same reaction performed in benzonitrile afforded crystalline UI4(N[triple bond]CPh)4 (3) in 78% isolated yield. In the solid state, 3 shows an eight-coordinate U(IV) atom in a "puckered" square antiprismatic geometry with U-N and U-I distances of 2.56(1) and 3.027(1) A, respectively. This benzonitrile UI4 adduct is a versatile U(IV) synthon that is soluble in methylene chloride, benzonitrile, and tetrahydrofuran, and moderately soluble in toluene and benzene, but decomposes in benzonitrile at 198 degrees C to [UI(N[triple bond]CPh)8][UI]6 (4), a U(III)/U(IV) salt analogous to 1. A toluene slurry of 3 treated with 2.2 equiv of Cp*MgCl.THF (Cp* = pentamethylcyclopentadienide) provided Cp*2UI2(N[triple bond]CPh) (5) in low yields. Single-crystal X-ray structure determination shows that the iodide ligands in 5 are in a rare cis configuration with an acute I-U-I angle of 83.16(7) degrees . Treatment of a methylene chloride solution of 3 with KTp* (Tp* = hydridotris(3,5-dimethylpyrazolylborate)) formed green TpUI3 (6) which was converted to yellow Tp*UI3(N[triple bond]CMe) (7) by rinsing with acetonitrile. Addition of 2.2 equiv of KTp* to a toluene solution of 3 followed by heating at 95 degrees C, filtration, and crystallization led to the isolation of the dinuclear species [Tp*UI(dmpz)]2[mu-O] (9) (dmpz = 3,5-dimethylpyrazolide), presumably formed by hydrolytic cleavage of excess KTp* by adventitious water. The Tp* complexes 6, 7, and 9 were characterized by single-crystal X-ray diffraction, NMR, FT-IR, and optical absorbance spectroscopies.     

Synthese und Eigenschaften Pentamethylcyclopentadienyl-substituierter PPC- bzw. AsPC-Dreiring-Systeme

Synthesis and Properties of Pentamethylcyclopentadienylsubstituted PPC and AsPC three-membered Rings Via the reaction of bis-(pentamethylcyclopentadienyl)diphosphene [Cp*P?PCp*, 1 ] and 1-(pentamethylcyclopentadienyl)-2-(2,4,6-tri^tbutylphenyl)- diphosphene [Cp*P?PMes*, 2 ] with the diazomethanes N₂CHR [R = H, Si(CH₃)₃] the four new diphosphiranes Cp*PPCp*CHSi(CH₃)₃, 4a , Cp*PPMes*CHSi(CH₃)₃, 4b , Cp*PPCp*CH₂, 5a , Cp*PPMes*CH₂, 5b , are obtained. The formation of 4a results via a 2 + 3-cyclo-addition product, which could be proved by nmr spectroscopy. The reaction of As-(pentamenthylcyclopentadienyl)-P-(2,4,6-tri^tbutylphenyl) arsaphosphene [Cp*As?PMes*, 3 ] with diazomethane leads to 1-(pentamethylcyclopentadienyl)-2-(2,4,6-tri^tbutylphenyl)-1-arsa-2 -phosphacyclopropane [phospharsiran, Cp*AsPMes*CH₂, 6 ]. Analysis of the structures by nmr spectroscopy gives clear evidence for a trans-orientation of the substituents at the El? P bond (El = As, P) in all of the three membered ring systems. For the diphosphirane Cp*PPCp*CH₂ ( 5a ) a Cp*-phosphorus bond cleavage by thermolysis cannot be observed. From the reaction of compound 5a with Cr(CO)₅thf one obtains 1-(pentacarbonylchrom)-1,2-bis(pentamethylcyclopentadienyl)-1,2- diphosphacyclo-propane, 7 .     

Mechanistic aspects of samarium-mediated sigma-bond activations of arene C-H and arylsilane Si-C bonds.

To investigate the potential role of Sm-Ph species as intermediates in the samarium-catalyzed redistribution of PhSiH3 to Ph2SiH2 and SiH4, the samarium phenyl complex [Cp*2SmPh]2 (1) was prepared by oxidation of Cp2*Sm (2) with HgPh2. Compound 1 thermally decomposes to yield benzene and the phenylene-bridged disamarium complex Cp*2Sm(mu-1,4-C6H4)SmCp*2 (3). This decomposition reaction appears to proceed through dissociation of 1 into monomeric Cp*2SmPh species which then react via unimolecular and bimolecular pathways, involving rate-limiting Cp* metalation and direct C-H activation, respectively. The observed rate law for this process is of the form: rate = k1[1] + k2[1]2. Complex 1 efficiently transfers its phenyl group to PhSiH3, with formation of Ph2SiH2 and [Cp*2Sm(mu-H)]2 (4). Quantitative Si-C bond cleavage of C6F5SiH3 is effected by the samarium hydride complex 4, yielding silane and [Cp*2Sm(mu-C6F5)]2 (5). In contrast, Si-H activation takes place upon reaction of 4 with o-MeOC6H4SiH3, affording the samarium silyl species [structure: see text] Cp*2SmSiH2(o-MeOC6H4) (7). Complex 7 rapidly decomposes to [Cp*2Sm(mu-o-MeOC6H4)]2 (6) and other samarium-containing products. Compounds 5 and 6 were prepared independently by oxidation of 2 with Hg(C6F5)2 and Hg(o-MeOC6H4)2, respectively. The mechanism of samarium-mediated redistribution at silicon, and chemoselectivity in sigma-bond metathesis reactions, are discussed.     

Fine-tuning of metallaborane geometries: chemistry of iridaboranes derived from the reaction of

From reaction of [(Cp*Ir)2HxCl(4-x)] (x=1, 0) and LiBH4, arachno-[[Cp*IrH2]B3H7](1) is produced in moderate yield concurrently with [Cp*IrH4]. In contrast, reaction of [(Cp*Ir)2H2Cl2] with LiBH4 results in arachno-[[Cp*IrH]2(mu-H)B2H5] (3) in high yield at room temperature but a mixture of 1 and [[Cp*IrH]2(mu-H)BH4] (2) at 0 degrees C. BH3 x THF converts 1 to arachno-[(Cp*IrHB4H9] (4) and 2 to 3 with 1 as a minor product. Further, reaction of 3 with excess of BH3 x THF results in formation of nido-[[Cp*Ir]2-(mu-H)B4H7] (6) formed by loss of H2 from the intermediate arachno-[[Cp*IrH]2B4H8] (5). Reaction of 1 with [Co2(CO)8] permits the isolation of two metallaboranes, arachno-[[Cp*Ir(CO)]-B3H7] (7) and nido-[1-[Cp*Ir]-2,3-Co2-(CO)4(mu-CO)B3H7] (8). Treatment of 4 with [Co2(CO)8] gives only one single mixed-metal metallaborane nido-[1-[Cp*Ir]-2-Co(CO)3B4H7 (9) in high yield. Finally, pyrolysis of 8 results in loss of hydrogen and formation of pileo-[1-[Cp*Ir]-2,3-Co2(CO)5B3H5] (10) with a BH-capped square-pyramidal structure. With kinetic control rational synthesis of a variety metallaboranes has been achieved by varying the number of chlorides in the monocyclopentadienylmetal halide dimer, reaction temperature, types of monoborane, and metal fragment sources.     

Reductive heterocoupling mediated by Cp*2U(2,2'-bpy)

Trivalent Cp*(2)U(2,2'-bpy) (2) (Cp* = C(5)Me(5), 2,2'-bpy = 2,2'-bipyridine), which has a monoanionic bipyridine, was treated with p-tolualdehyde (a), furfuraldehyde (b), acetone (c), and benzophenone (d). Reduction of the C[double bond, length as m-dash]O bond followed by radical coupling with bipyridine forms the U(iv) derivatives [Cp*(2)U(2,2'-bpy)(OCRR')] (3a-d).     

Synthesis and reactions of group 6 metal half-sandwich complexes of 2,2-dicyanoethylene-1,1-dichalcogenolates [(Cp*)M[E(2)C=C(CN)(2)](2)]-(M = Mo,W; E = S,Se)

A series of group 6 transition metal half-sandwich complexes with 1,1-dichalcogenide ligands have been prepared by the reactions of Cp*MCl(4)(Cp* = eta(5)-C(5)Me(5); M = Mo, W) with the potassium salt of 2,2-dicyanoethylene-1,1-dithiolate, (KS)(2)C=C(CN)(2) (K(2)-i-mnt), or the analogous seleno compound, (KSe)(2)C=C(CN)(2) (K(2)-i-mns). The reaction of Cp*MCl(4) with (KS)(2)C=C(CN)(2) in a 1:3 molar ratio in CH(3)CN gave rise to K[Cp*M(S(2)C=C(CN)(2))(2)] (M = Mo, 1a, 74%; M = W, 2a, 46%). Under the same conditions, the reaction of Cp*MoCl(4) with 3 equiv of (KSe)(2)C=C(CN)(2) afforded K[Cp*Mo(Se(2)C=C(CN)(2))(2)] (3a) and K[Cp*Mo(Se(2)C=C(CN)(2))(Se(Se(2))C=C(CN)(2))] (4) in respective yields of 45% and 25%. Cation exchange reactions of 1a, 2a, and 3a with Et(4)NBr resulted in isolation of (Et(4)N)[Cp*Mo(S(2)C=C(CN)(2))(2)] (1b), (Et(4)N)[Cp*W(S(2)C=C(CN)(2))(2)] (2b), and (Et(4)N)[Cp*Mo(Se(2)C=C(CN)(2))(2)] (3b), respectively. Complex 4 crystallized with one THF and one CH(3)CN molecule as a three-dimensional network structure. Inspection of the reaction of Cp*WCl(4) with (KSe)(2)C=C(CN)(2) by ESI-MS revealed the existence of three species in CH(3)CN, [Cp*W(Se(2)C=C(CN)(2))(2)]-, [Cp*W(Se(2)C=C(CN)(2))(Se(Se(2))C=C(CN)(2))]-, and [Cp*W(Se(Se(2))C=C(CN)(2))(2)]-, of which [Cp*W(Se(2)C=C(CN)(2))(Se(Se(2))C=C(CN)(2))]-(5) was isolated as the main product. Treatment of 2a with 1/4 equiv of S(8) in refluxing THF resulted in sulfur insertion and gave rise to K[Cp*W(S(2)C=C(CN)(2))(S(S(2))C=C(CN)(2))](6), which crystallized with two THF molecules forming a three-dimensional network structure. 6 can also be prepared by refluxing 2a with 1/4 equiv of S(8) in THF. 3a readily added one Se atom upon treatment with 1 mol of Se powder in THF to give 4 in high yield, while the treatment of 3a or 4 with 2 equiv of Na(2)Se in THF led to formation of a dinuclear complex [(Cp*Mo)(2)(mu-Se)(mu-Se(Se(3))C=C(CN)(2))] (7). The structure of 7 consists of two Cp*Mo units bridged by a Se(2-) and a [Se(Se(3))C=C(CN)(2)](2-) ligand in which the triselenido group is arranged in a nearly linear way (163 degrees). The reaction of 2a with 2 equiv of CuBr in CH(3)CN yielded a trinuclear complex [Cp*WCu(2)(mu-Br)(mu(3)-S(2)C=C(CN)(2))(2)] (8), which crystallized with one CH(3)CN and generated a one-dimensional chain polymer through bonding of Cu to the N of the cyano groups.     

A new titanium building block for early-late heterometallic complexes; preparation of a new tetrameric metallomacrocycle by self assembly

The new titanium dicarboxylate complex Cp*TiMe(OOC)2py (2) [Cp*=eta5-C5Me5; (OOC)2py = 2,6-pyridinedicarboxylate] has been synthesized. The reaction of complex 2 with water renders [Cp*Ti(OOC)2py]2O (3). The molecular structure of 3 has been studied by X-ray diffraction methods. Complex 2 reacts with isocyanides to yield the respective iminoacyl derivatives Cp*Ti(eta2-MeCNR)(OOC)2py [R=tBu (4), 2,6-dimethylphenyl (xylyl) (5)]. The molecular structure of complex4 has been established by X-ray diffraction. Compound 2 has been employed as a new building block for the preparation of new early-late heterometallic compounds; it reacts with [M(mu-OH)(COD)]2 (M = Rh, Ir) to give the corresponding tetranuclear metallomacrocycle derivatives [Cp*Ti{(OOC)(2)py}(mu-O)M(COD)]2 [M = Rh (6); Ir (7)]. The molecular structure of 6 has been established by X-ray diffraction.     

Synthesis and reactivities of a bis(cyanamido)-capped triruthenium complex

The tetraruthenium complex [Cp*RuCl]4 (Cp* = eta(5)-C(5)Me(5)) reacts with Na(2)NCN to afford the anionic bis(cyanamido)-capped triruthenium complex [(Cp*Ru)3(micro(3)-NCN)(2)]- ((2-)), which undergoes single electron oxidation to form [(Cp*Ru)3(micro(3)-NCN)2] upon workup with 1 equiv. of [Cp(2)Fe](PF(6)) (Cp = eta(5)-C(5)H(5)). Treatment of (2-) with 1 equiv. of HCl at room temperature leads to the protonation of one of the Ru-Ru edges to give the hydrido-bridged complex [(Cp*Ru)3(micro-H)(micro-NCN)2], while the cationic side-on NCNH(2) complex [(Cp*Ru)3(micro-Cl)(micro(3)-NCN)(micro(3)-NCNH(2)-1kappaC,N:2kappaC:3kappaN)]Cl (5) is obtained by the reaction of (2-) with an excess amount of HCl at -78 degrees C. On the other hand, the reaction of (2-) with BR(3) (R = Et, Ph) results in the ligation of two BR(3) molecules to the terminal nitrogen atoms of the cyanamido ligands to yield the bis(borane) adduct (PPN)[(Cp*Ru)(3){(micro(4)-NCN)(BR(3))}(2)] (6, PPN = Ph(3)PNPPPh(3)). 6b (R = Et) slowly liberates one BEt(3) molecule in acetone to give the mono(borane) adduct (PPN)[(Cp*Ru)3(micro(3)-NCN){(micro(4)-NCN)(BEt(3))}] (7). (2-) is also shown to react with [AuCl(PPh(3))] or PhCOCl to afford the tetranuclear heterometallic complex [(Cp*Ru)3(micro(3)-NCN){(micro(4)-NCN)(AuPPh(3))}] (8) or the benzoylcyanamido complex [(Cp*Ru)3(micro(3)-NCN)(micro(3)-NCNCOPh)] in which the Au(PPh(3))+ or benzoyl fragment is bound to the terminal nitrogen atom of a cyanamido ligand. The molecular structures of PPN+(2-), 5.C(6)H(6), 7 and 8.C(6)H(6) have been determined by single-crystal X-ray analyses.     

Yttrium and erbium halide complexes with [{Ti(eta5-C5Me5)(mu-NH)}3(mu3-N)] as a neutral tridentate ligand

Treatment of [{TiCp*(mu-NH)} 3(mu 3-N)] ( 1; Cp* = eta (5)-C 5Me 5) with yttrium and erbium halide complexes [MCl 3(THF) 3.5] and [MCpCl 2(THF) 3] (Cp = eta (5)-C 5H 5) gives cube-type adducts [Cl 3M{(mu 3-NH) 3Ti 3Cp* 3(mu 3-N)}] and [CpCl 2M{(mu 3-NH) 3Ti 3Cp* 3(mu 3-N)}]. An analogous reaction of 1 with [{MCp 2Cl} 2] in toluene affords [Cp 3M(mu-Cl)ClCpM{(mu 3-NH) 3Ti 3Cp* 3(mu 3-N)}] (M = Y, Er).     

New disulfido molybdenum-manganese complexes exhibit facile addition of small molecules to the sulfur atoms

The reaction of Mn(2)(CO)(7)(mu-S2) (1) with [CpMo(CO)(3)](2) (Cp = C(5)H(5)) and [Cp*Mo(CO)(3)](2) (Cp* = C(5)(CH(3))(5)) yielded the new mixed-metal disulfide complexes CpMoMn(CO)(5)(mu-S2) (2) and Cp*MoMn(CO)(5)(mu-S2) (3) by a metal-metal exchange reaction. Compounds 2 and 3 both contain a bridging disulfido ligand lying perpendicular to the Mo-Mn bond. The bond distances are Mo-Mn = 2.8421(10) and 2.8914(5) A and S-S = 2.042(2) and 1.9973(10) A for 2 and 3, respectively. A tetranuclear metal side product CpMoMn(3)(CO)(13)(mu3-S)(mu4-S) (4) was also isolated from the reaction of 1 with [CpMo(CO)(3)](2). Compounds 2 and 3 react with CO to yield the dithiocarbonato complexes CpMoMn(CO)(5)[mu-SC(=O)S] (5) and Cp*MoMn(CO)(5)[mu-SC(=O)S] (6) by insertion of CO into the S-S bond. Similarly, tert-butylisocyanide was inserted into the S-S bond of 2 and 3 to yield the complexes CpMoMn(CO)(5)[mu-S(C=NBu(t))S] (7) and Cp*MoMn(CO)(5)[mu-S(C=NBu(t))S] (8), respectively. Ethylene and dimethylacetylene dicarboxylate also inserted into the S-S bond of 2 and 3 at room temperature to yield the ethanedithiolato ligand bridged complexes CpMoMn(CO)(5)(mu-SCH(2)CH(2)S) (9), Cp*MoMn(CO)(5)(mu-SCH(2)CH(2)S) (10), CpMoMn(CO)(5)[mu-SC(CO(2)Me)=C(CO(2)Me)S] (11), and Cp*MoMn(CO)(5)[mu-SC(CO(2)Me)=C(CO(2)Me)S] (12). Allene was found to insert into the S-S bond of 2 by using one of its two double bonds to yield the complex CpMoMn(CO)(5)[mu-SCH(2)C(=CH(2))S] (13). The molecular structures of the new complexes 2-7 and 9-13 were established by single-crystal X-ray diffraction analyses.     

Cleavage of hydrazine N-N bonds by RuMo3S4 cubane-type clusters

The mixed-metal cubane-type clusters [(Cp*Mo)3(mu3-S)4RuH2(PR3)][PF(6)] [Cp* = eta5-C5Me5; R = Ph (2), Cy (5)] were effective for the N-N bond cleavage of hydrazine and phenylhydrazine via a disproportionation reaction. The ammonia cluster [(C*Mo)3(mu3-S)4Ru(NH3)(PPh3)][PF6] (3) and/or the unprecedented double-cubane-type cluster with bridging nitrogenous ligands [{(Cp*Mo)3(mu3-S)4Ru}2(mu2-NH2)(mu2-NHNH2)][PF6]2 (4) were isolated from the reaction mixtures, and their structures were determined by X-ray diffraction studies.     

Experimental and Computational Studies on a Base-Free Terminal Uranium Phosphinidene Metallocene

The first stable base-free terminal uranium phosphinidene metallocene is presented; and its structure and reactivity have been studied in detail and compared to that of the corresponding thorium derivative. Salt metathesis reaction of the methyl iodide uranium metallocene Cp’’’₂U(I)Me ( 2 , Cp’’’=η⁵-1,2,4-(Me₃C)₃C₅H₂) with Mes*PHK (Mes*=2,4,6-(Me₃C)₃C₆H₂) in THF yields the base-free terminal uranium phosphinidene metallocene, Cp’’’₂U=PMes* ( 3 ). In addition, density functional theory (DFT) studies suggest substantial 5f orbital contributions to the bonding within the uranium phosphinidene [U]=PAr moiety, which results in a more covalent bonding between the [Cp’’’₂U]²⁺ and [Mes*P]²⁻ fragments than that for the related thorium derivative. This difference in bonding besides steric reasons causes different reactivity patterns for both molecules. Therefore, the uranium derivative 3 may act as a Cp’’’₂U(II) synthon releasing the phosphinidene moiety (Mes*P:) when treated with alkynes or a variety of hetero-unsaturated molecules such as imines, thiazoles, ketazines, bipy, organic azides, diazene derivatives, ketones, and carbodiimides.     

含半夹心结构铑的1,1'-二硫(硒、碲)二茂铁化合物

以半夹心结构铑的化合物Cp*Rh(CN^tBu)Cl2(1)(Cp*=η^5-C5Me5)与Fe(C5H4ELi)2.2THF反应,合成出异双核二茂铁化合物Cp*Rh(CN^tBu)(EC5H4)2Fe[E=S(2),Se(3),Te(4)]。通过AgBF4氧化2和3得到二茂铁离子型化合物[Cp*Rh(CN^tBu)(EC5H4)2Fe]BF4[E=S(5),Se(6)]。采用元素分析、红外光谱、^1H和13CNMR谱以及EI-MS表征了所合成的化合物。