Crystal structure and DFT calculations of Cp2NbH(SiIMe2)(SiFMe2): an asymmetric bis(silyl) niobocene hydride complex

An asymmetric bis(silyl) niobocene hydride complex, namely, bis(η⁵-cyclopentadienyl)(fluorodimethylsilyl)hydrido(iododimethylsilyl)niobium, [Nb(C₅H₅)₂(C₂H₆FSi)(C₂H₆ISi)H] or Cp₂NbH(SiIMe₂)(SiFMe₂), has been studied to determine the effect of the silyl ligand on the position of the hydride attached to the Nb atom. It has been shown that when a Group 17 atom is substituted onto one of the silyl ligands, there is a greater interaction between the hydride and this ligand, as demonstrated by a shorter Si…H distance. In the present work, we have investigated the effect when the silyl ligands are substituted by different Group 17 atoms. We present here the structure and DFT calculations of Cp₂NbH(SiIMe₂)(SiFMe₂), showing that the position of the hydride is located between the two silyl ligands. The results from our investigation show that the hydride is closer to the silyl ligand that is substituted by fluorine.     

Synthesis, characterization, and X-ray structure determination of [Au18(P)2(PPh)4(PHPh)(dppm)6]Cl3

The reaction of [(AuCl)2dppm] (dppm=Ph2PCH2PPh2) with PhP(SiMe3)2 and P(SiMe3)3 leads to the formation of the gold cluster compound [Au18(P)2(PPh)4(PHPh)(dppm)6]Cl3 (1). The crystal structure investigation shows a central Au7P2 unit formed by two P centered gold tetrahedra sharing the central gold corner. This central unit is surrounded by a 10-membered Au5P5 ring which, together with the remaining six gold atoms, builds two Au4P rectangular and two Au3P trigonal pyramids. The different structure motifs are connected by the phosphine ligands. The compound has been characterized using microanalysis, IR spectroscopy, ESI-MS, and 31P NMR techniques. Luminescence measurements have also been carried out.     

A new reaction of [Cp((CO)2Fe(PPh2H)]PF6 with NaBH4 to give Cp(CO)(H)Fe(PPh2H) via Cp(CO)2FeH and PPh2H

[Cp((CO)₂Fe(PPh₂H)]PF₆ reacts with NaBH₄ to give the intermediates CpFe(CO)₂H and PPh₂H, which are then converted into Cp(CO)(H)Fe(PPh₂H). [Cp(CO)₂FeL]PF₆ (L = P(OMe)₃, P(OEt)₃ and P(OⁱPr)₃) reacts with NaBH₄ to give the product Cp(CO)(H)FeL directly without Cp(CO)₂FeH and L even being formed transiently. The proposed reaction mechanism is that H⁻ attacks th phosphorus atom to give a metallaphosphorane complex, followed by coupling between a Cp(CO)₂Fe fragment and H on the hypervalent phosphorus.     

Synthesis,spectroscopic characterization,and crystal structure of the bimetallic complex [Ni2(mu-CO)(CO)2(mu-NH(PPh2)2)2

The dinuclear Ni(0) complex [Ni2(mu-CO)(CO)2(mu-dppa)2] (1; dppa = bis(diphenylphosphino)amine) was synthesized by two routes in good yield. Complex 1 has a triclinic crystal system and P1 space group, with a = 13.009(1) A, b = 13.063(2) A, c = 14.664(2) A, alpha = 79.91(1) degrees, beta = 79.96(1) degrees, gamma = 71.32(1) degrees, and Z = 2. The structure of this compound exhibits two mu-coordinated dppa ligands in a cis, cis arrangement. Nickel atoms are at a 2.5824(7) A distance. Theoretical calculations predict a 0.39 bond order between metal atoms. The cyclic voltammograms show two quasi-reversible redox pairs, which correspond to the successive oxidation of the metal centers. The dinuclear complex described absorbs carbon monoxide, yielding a mixture of nickel carbonyl compounds.     

Crystal structure of the copper(I) complex Cu(py-Clan)(PPh3)I

Journal of Structural Chemistry - A mixed ligand copper(I) Schiff base complex [Cu(py-Clan)(PPh3)I], where py-Clan = = 4-chlorophenylpyridine-2-ylmethyleneamine, is synthesized and structurally...     

Synthesis and molecular structure of the complex YbI(bipy)(DME)2

The reaction of the naphthalene complex of ytterbium, [Yb(DME)₂]₂(μ-C₁₀H₈), with 2,2′-bipyridine in 1,2-dimethoxyethane afforded the Yb^II complex containing the 2,2′-bipyridine radical anion. The resulting complex YbI(bipy)(DME)₂ was characterized by IR and ESR spectroscopy, X-ray diffraction analysis, and magnetochemistry. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2341–2344, November, 1998.     

Reaction of alkenes with trans-MeOIr(CO)(PPh3)2. Crystal and molecular structure of the pentacoordinate alkoxy-alkene iridium(I) complex,MeOIr(CO)(PPh3)2(TCNE)

The reaction of trans-MeOIr(CO)(PPh₃)₂ with TCNE (tetracyanoethylene) gives rise to the stable adduct MeOIr(CO)(PPh₃)₂(TCNE), the structure of which has been determined via a single-crystal X-ray diffraction study. This complex crystallizes in the centrosymmetric orthorhombic space group Pbca (D¹⁵_2h; No. 61) with a 17.806(4), b 20.769(4), c 20.589(6) Å, V 7614(3) ų and Z = 8. Diffraction data (Mo-K_α, 2θ = 5–45°) were collected on a Syntex P2₁ automated four-circle diffractometer and the structure was solved and refined to R_F 6.2% for 3502 data with |F₀| > 3σ(|F₀|) (R_F 4.3% for those 2775 data with |F₀| > 6 σ(|F₀|)). The central iridium atom has a distorted trigonal bipyramidal coordination geometry in which the methoxy group (Ir-OMe 2.057(8) Å) and carbonyl ligand (Ir-CO 1.897(14) Å) occupy axial sites with ∠MeOIrCO 174.7(4)°. The two triphenylphosphine ligands occupy equatorial sites (IrP(1) 2.399(3), IrP(2) 2.390(3) Å, ∠P(1)IrP(2) 110.32(11)° and the TCNE ligand is linked in an η² “face-on” fashion with the olefinic bond parallel to the equatorial coordination plane (IrC(4) 2.176(10), IrC(7) 2.160(12) Å) and lengthened substantially from its value in the free olefin (C(4)C(7) 1.539(17) Å).     

Synthesis, properties, and the crystal structure of the complex Cp2Yb(DAD)

The diazadiene complex of trivalent ytterbium, Cp₂Yb(DAD) (1) (DAD=Bu^t−N=CH−CH=N−Bu^t) was prepared according to three different procedures, namely, by oxidation of Cp₂Yb(THF)₂ with diazadiene in THF, by the reaction of Cp₂YbCl with DAD²⁻Na⁺ ₂ taken in a ratio of 2∶1, and by the reaction of Cp₂YbCl(THF) with DAD²⁻Na⁺ ₂ taken in a ratio of 1∶1. Complex1 was characterized by microanalysis, IR spectroscopy, magnetochemistry, and X-ray diffraction analysis. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 384–386, February, 1999.     

Synthesis and reactivity of the monomeric late-transition-metal parent amido complex [Ir(Cp*)(PMe3)(Ph)(NH2)

The late-transition-metal parent amido compound [Ir(Cp*)(PMe3)(Ph)(NH2)] (2) has been synthesized by deprotonation of the corresponding ammine complex [Ir(Cp*)(PMe3)(Ph)(NH3)][OTf] (6) with KN(SiMe3)2. An X-ray structure determination has ascertained its monomeric nature. Proton-transfer studies indicate that 2 can successfully deprotonate p-nitrophenylacetonitrile, aniline, and phenol. Crystallographic analysis has revealed that the ion pair [Ir(Cp*)(PMe3)(Ph)(NH3)][OPh] (8) exists as a hydrogen-bonded dimer in the solid state. Reactions of 2 with isocyanates and carbodiimides lead to overall insertion of the heterocumulenes into the N--H bond of the Ir-bonded amido group, demonstrating the ability of 2 to act as an efficient nucleophile. Intriguing reactivity is observed when amide 2 reacts with CO or 2,6-dimethylphenyl isocyanide. eta4-Tetramethylfulvene complexes [Ir(eta4-C5Me4CH2)(PMe3)(Ph)(L)] (L=CO (15), CNC6H3-2,6-(CH3)2 (16)) are formed in solution through displacement of the amido group by the incoming ligand followed by deprotonation of a methyl group on the Cp* ring and liberation of ammonia. Conclusive evidence for the presence of the Ir-bonded eta4-tetramethylfulvene moiety in the solid state has been provided by an X-ray diffraction study of complex 16.     

Coordination Chemistry of P4S3 and P4Se3 towards the Iron Fragments [Fe(Cp)(CO)2]+ and [Fe(Cp)(PPh3)(CO)]+

The complexes Ag(L)_n[WCA] (L=P₄S₃, P₄Se₃, As₄S₃, and As₄S₄; [WCA]=[Al(OR^F)₄]⁻ and [F{Al(OR^F)₃}₂]⁻; R^F=C(CF₃)₃; WCA=weakly coordinating anion) were tested for their performance as ligand-transfer reagents to transfer the poorly soluble nortricyclane cages P₄S₃, P₄Se₃, and As₄S₃ as well as realgar As₄S₄ to different transition-metal fragments. As₄S₄ and As₄S₃ with the poorest solubility did not yield complexes. However, the more soluble silver-coordinated P₄S₃ and P₄Se₃ cages were transferred to the electron-poor Fp⁺ moiety ([CpFe(CO)₂]⁺). Thus, reaction of the silver salt in the presence of the ligand with Fp−Br yielded [Fp−P₄S₃][Al(OR^F)₄] ( 1 a ), [Fp−P₄S₃][F(Al(OR^F)₃)₂] ( 1 b ), and [Fp−P₄Se₃][Al(OR^F)₄] ( 2 ). Reactions with P₄S₃ also yielded [FpPPh₃−P₄S₃][Al(OR^F)₄] ( 3 ), a complex with the more electron-rich monophosphine-substituted Fp⁺ analogue [FpPPh₃]⁺ ([CpFe(PPh₃)(CO)]⁺). All complex salts were characterized by single-crystal XRD, NMR, Raman, and IR spectroscopy. Interestingly, they show characteristic blueshifts of the vibrational modes of the cage, as well as structural contractions of the cages upon coordination to the Fp/FpPPh₃ moieties, which oppose the typically observed cage expansions that lead to redshifts in the spectra. Structure, bonding, and thermodynamics were investigated by DFT calculations, which support the observed cage contractions. Its reason is assigned to σ and π donation from the slightly P−P and P−E antibonding P₄E₃-cage HOMO (e symmetry) to the metal acceptor fragment.     

Synthesis,structure, and reactions of a nitroxyl complex of iridium(III), cis,trans-IrHCl2(NH=O)(PPh3)2

Reaction of Ir(NO)(PPh3)3 with anhydrous HCl results in addition of 2 equivalents of HCl with formal protonation of the nitrosyl ligand, affording the unusual six-co-ordinate nitroxyl complex cis,trans-IrHCl2(NH=O)(PPh3)2.     

Reaction properties of the trans-hyponitrite complex [Ru2(CO)4(mu-H)(mu-PBu(t)2)(mu-Ph2PCH2PPh2)(mu-eta2-ONNO)

The protonation of [Ru(2)(CO)(4)(mu-H)(mu-PBu(t)()(2))(mu-dppm)(mu-eta(2)-ONNO)] (1) with HBF(4) occurs at the oxygen of the noncoordinating side of the trans-hyponitrite ligand to give [Ru(2)(CO)(4)(mu-H)(mu-PBu(t)()(2))(mu-dppm)(mu-eta(2)-ONNOH)][BF(4)] (2) in good yield. The monoprotonated hyponitrite in 2 is deprotonated easily by strong bases to regenerate 1. Furthermore, 1 reacts with the methylating reagent [Me(3)O][BF(4)] to afford [Ru(2)(CO)(4)(mu-H)(mu-PBu(t)()(2))(mu-dppm)(mu-eta(2)-ONNOMe)][BF(4)] (3). The molecular structures of 2 and 3 have been determined crystallographically, and the structure of 2 is discussed with the results of the DFT/B3LYP calculations on the model complex [Ru(2)(CO)(4)(mu-H)(mu-PH(2))(mu-H(2)PCH(2)PH(2))(mu-eta(2)-ONNOH)](+) (2a). Moreover, the thermolysis of 2 in ethanol affords [Ru(2)(CO)(4)(mu-H)(mu-OH)(mu-PBu(t)()(2))(mu-dppm)][BF(4)] (4) in high yield, and the deprotonation of 4 by DBU in THF yields the novel complex [Ru(2)(CO)(4)(mu-OH)(mu-PBu(t)()(2))(mu-dppm)] (5).     

Synthesis,molecular and electronic structure of [ReCl2(N2COPh)(C4N2H4)(PPh3)2]

A new organodiazenido rhenium complex, [ReCl₂(N₂COPh)(C₄N₂H₄)(PPh₃)₂] has been obtained from the direct reaction of [ReCl₂(η²–N₂COPh–N′,O)(PPh₃)₂] with pyrazine in acetone. The complex has been characterized by spectroscopic methods and its structure determined using single-crystal X-ray diffraction techniques.     

The ruthenium pyrazolonate complex Ru(PMIP)2(PPh3)2: Synthesis, structure, and some properties

The new ruthenium(II) complex Ru(PMIP)₂(PPh₃)₂ (HPMIP is 4-isobutyryl-3-methyl-1-phe-nylpyrazol-5-one) was obtained from RuCl₂(PPh₃)₃ and Na(PMIP)(DME) (DME is dimethoxyethane). The structures of the complex obtained and the starting sodium pyrazolonate were determined by X-ray diffraction. The ruthenium pyrazolonate complex initiates metathetical norbornene polymerization producing high-molecular-weight polynorbornene in low yield.     

Silver(I) thiosemicarbazone complex [Ag(catsc)(PPh3)2]NO3: Synthesis,characterization, crystal structure,and antibacterial study

We report the synthesis, characterization and crystal structure of a new mononuclear silver(I) complex, [Ag(catsc)(PPh₃)₂]NO₃ (catsc = 3-phenylpropenalthiosemicarbazone). The complex was prepared by the reaction of catsc and AgNO₃ in the presence of PPh₃ and characterized by elemental analysis (CHN), FTIR, ¹H, ¹³C and ³¹P NMR spectroscopy, and single-crystal X-ray diffraction. In the complex, catsc acts as a bidentate NS ligand while the nitrate is a counter ion. The silver ion is coordinated by a bidentate ligand and two PPh₃ in the form of a distorted tetrahedron. In addition, the antibacterial effect of the complex was studied against the standard strains of two gram-positive (Staphylococcus aureus and Enterococcus faecalis) and two gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria.     

Synthesis of RuHCl(CO)(Hdmpz)(L)2 (L=PPh3, AsPh3, and Hdmpz=3,5-dimethylpyrazole) and crystal structure of RuHCl(CO)(Hdmpz)(AsPh3)2

Treatment of RuHCl(CO)(L)₃ with a slight excess amount of K[HB(3,5-Me₂pz)₃] in boiling MeOH solution yielded unusual 3,5-dimethylpyrzaole (Hdmpz) complexes, RuHCl(CO)(Hdmpz)(L)₂ (L=PPh₃, 1 or AsPh₃, 2). Unexpectedly the dissociation of the bonds between the boron atom and the nitrogen atoms of the potentially tridentate [HB(3,5-Me₂pz)₃]⁻ ligand during the coordination of the ligand to the Ru^II metal has been observed. In a separate preparation, the RuHCl(CO)(Hdmpz)(PPh₃)₂ complex has also been synthesized from the reaction between RuHCl(CO)(PPh₃)₃ and the monodentate Hdmpz ligand. Complexes 1 and 2 have been characterized by elemental analysis, IR and ¹H NMR spectroscopies. Compound 1 has also been prepared by the reaction between RuHCl(CO)(PPh₃)₃ and K[H₂B(3,5-Me₂pz)₂] in boiling toluene solution. The crystal structure of 2 has been studied by X-ray crystallography. The geometrical structure around Ru^II of 2 is a distorted octahedral structure. The crystal structure of 2 consists of a discrete monomeric compound. It is interesting to find that the sterically-demanding [HB(3,5-Me₂pz)₃]⁻ or [H₂B(3,5-Me₂pz)₂]⁻ ligands break up during the reaction with the Ru^II complexes to form the neutral 3,5-dimethylpyrazole complexes. In contrast to these observations, [H₂Bpz₂]⁻ and [H₂B(4-Brpz)₂]⁻ ligands form very stable Ru^II complexes.     

Synthesis of low-valent thiocarbonyl complexes via 1,2-elimination of methylthiol from cis-metal-hydrido-dithiomethylester complexes. Os(cs)(CO)2(PPh3)2 and IrCl(CS)(PPh3)2.

[OS(η²-CS₂Me)(CO)₂(PPH₃)₂]⁺ and [Ir(η²-CS₂Me)Cl(CO)(PPh₃)₂)⁺ react with NaBH₄ giving OsH(CS₂Me)(CO)₂(PPh₃)₂ and IrH(CS₂Me)Cl(CO)(PPh₃)₂ respectively; These compounds contain mutually $\text{cis}$ hydride and η¹-dithiomethylester ligands and upon heating undergo 1,2-elimination of MeSH producing Os(CS)(CO)₂(PPh₃)₂ and IrCl(CS)(PPh₃)₂.