1H, 13C and 31P NMR studies of some (C6H5)3−nPRn and (C6H5)3−nPRn Cr(CO)5 (n = 0–3; R  H,CH3, C2H5, i-C3H7, t-C4H9) derivatives

The ³¹P chemical shift of the (C₆H₅)_3−nPR_n and (C₆H₅)_3−nPR_nCr(CO)₅ (n = 0–3; R  H, CH₃, C₂H₅, i-C₃H₇, t-C₄H₉) derivatives is dominated by the steric effect. A small inductive effect is also operative but there are no indications of notable (d_Cr→d_P)π back-bonding. The ¹³C chemical shift of the phenyl carbon atoms indicates that (p_ring-d_P)π electron delocalization is unimportant.The ¹³C chemical shift of the carbonyl carbon atoms, which is mainly governed by the mean excitation energy, confirms the conclusion that there are no notable changes in (d_Cr→d_P)π back-bonding in this series of compounds.     

BBr3-Mediated P(III)-Directed C−H Borylation of Phosphines

Transition-metal-catalyzed C−H borylation has been widely used in the preparation of organoboron compounds. Here, we developed a general protocol on metal-free P(III)-directed C−H borylation of phosphines mediated by BBr₃, resulting in the formation of products bearing both phosphorus and boron. The development of the metal-free strategy to mimic previous metallic processes has shown low cost, superior practicality, and environmental friendliness. Density functional theory (DFT) calculations demonstrate the preferred pathway for this metal-free directed C−H borylation process.     

NMR study (1H, 13C and 31P) of the {(C2H5)2N}nPX3−n compounds (X = Cl,C2H5; n = 0, 1, 2, 3)

¹H, ¹³C and ³¹P NMR data of the compounds {(C₂H₅)₂N}_nPX_3−n, (X = Cl, C₂H₅; n = 0, 1, 2, 3) are reported. While the ¹H and ¹³C resonances from the PEt moiety rather follow the electron-withdrawing effect of the NEt₂ substituent, ¹H and ¹³C chemical shift data from the NEt₂ moiety reveal a quite important shift contribution originating from sterically induced polarization of the CH bonds . ³¹P chemical shift data are interpreted in terms of inductive effects but the anomalous diamagnetic shift deviation from linearity for X = Cl suggests a minor contribution from

multiple bonding. The general trend observed in the ³¹P-couplings is quite straightforward and can be qualitatively explained by Bent's rule.     

Reactivity, 31P, 13C, 1H NMR and IR Studies of Δ5-3-Dimethylamino-3-Oxo-1,2,3- Diazaphospholines

Abstract

In precedent work research (1)(2) we have reported a new synthesis method of the Δ⁵-3- dimethylamino-3-oxo-l,2,3 diazaphospholine derivatives (D_i). In this present work, we have to detail the reactivity and the structure of those heterocycles by N.M.R. (³¹P, ¹³C, ¹H) and I.R. In Infra-Red spectroscopy, we show the existence of the intermolecular hydrogen bond of some compounds. The spectrum(³¹P, ¹³C, ¹H) and I.R. was reported of (D_i).     

Vibrational spectra and electronic structure of 1-germatranol, 1,1-quasi-germatrandiole,and 1,1,1-hypogermatrantriole (HO)4−n Ge(OCH2CH2) n NR3−n (R = H,Me; n = 1–3)

IR spectra of 1-germatranol, 1,1-quasi-germatrandiole, 1,1,1-hypogermatrantriole with a general formula (HO)_4?n Ge(OCH₂CH₂) _n NR_3?n (n = 1–3) are obtained. At the B3LYP/aug-cc-pVDZ density functional level the equilibrium structures and vibrational spectra of these compounds along with their hydrogen-bonded dimers are calculated. Based on the calculations the band assignment is performed in the IR spectra of 1-germatranol, 1,1-quasi-germatrandiole, and 1,1,1-hypogermatrantriole. The existence of dimers is manifested in the IR spectra as the absence of bands in the frequency ranges characteristic of the bending vibrations of Ge-OH groups and the presence of bands in the vibrational range of hydrogen-bonded germatranyl groups.     

31P-NMR and X-ray studies of new rhodium(I) β-ketoiminato complexes Rh(R1C(O)CHC(NH)R2)(CO)(PZ3) where PZ3=PPh3, PCy3, P(OPh)3 or P(NC4H4)3

The substitution of the CO ligand in rhodium(I) β-ketoiminato complexes Rh(R₁{O,N}R₂)(CO)₂ ({O,N}=R₁C(O)CHC(NH)R₂; R₁, R₂=CF₃, Me, CMe₃ in several combinations) by phosphorus ligands PZ₃ (PZ₃=PCy₃, PPh₃, P(OPh)₃, P(NC₄H₄)₃) leads to Rh(R₁{O,N}R₂)(CO)(PZ₃) complexes characterised by ³¹P{¹H}-NMR and X-ray methods. The stronger σ-donor PZ₃ ligands (PZ₃=PCy₃, PPh₃) substitute almost exclusively the CO group trans to N, forming P-trans-to-N isomers. The complexes Rh(CF₃{O,N}Me)(CO)(PCy₃) (II), Rh(CF₃{O,N}CMe₃)(CO)(PCy₃) (III), Rh(CF₃{O,N}Me)(CO)(PPh₃) (IV) and Rh(CF₃{O,N}CMe)(CO)(PPh₃) (V) are of a square-planar geometry with a slight tetrahedral distortion around the rhodium atom in II, III and V. The RhP(PCy₃) bonds are slightly longer than the RhP(PPh₃) bonds. The reaction of stoichiometric amounts of the less basic P(OPh)₃ or P(NC₄H₄)₃ ligands leads to the formation of both isomers of the Rh(R₁{O,N}R₂)(CO)(P(OPh)₃) or Rh(R₁{O,N}R₂)(CO)(P(NC₄H₄)₃) complex in comparable yields. The RhP(P(OPh)₃) distance (2.195(2) Å) in the isomer of Rh(CF₃{O,N}CMe₃)(CO)(P(OPh)₃) with P(OPh)₃ coordinated trans to N (VI) is ca. 0.04 Å longer than in the isomer of that complex with P(OPh)₃ coordinated trans to O (VII). The CO substitution in Rh(R₁{O,N}R₂)(CO)₂ by PZ₃ ligands (PPh₃, PCy₃, P(OPh)₃) causes the shortening of the RhC(CO) bond by ca. 0.04 Å compared to Rh(CF₃{O,N}Me)(CO)₂ (I), making difficult the coordination of another PZ₃ ligand, especially one with stronger σ-donor properties. The more π-acceptor P(OPh)₃ ligands form bis-phosphito complexes and Rh(CF₃{O,N}CMe₃){P(OPh)₃}₂ (VIII) exhibits inequivalence of the two P(OPh)₃ ligands in solution (³¹P-NMR) as well as in solid form (X-ray).     

NMR studies on [VS4–Cun] (n=3, 4, 5, 6) clusters

The complexes containing [VS₄–Cu_n] (n=3, 4, 5, 6) clusters were characterized by NMR spectra. The relationship between the ⁵¹V NMR chemical shift and the number of copper atoms in a cluster was established. ⁵¹V NMR chemical shifts were used to identify possible products of the reactions of Cu(PPh₃)Cl and [VS₄–Cu₃] with various mole ratios in CDCl₃ in order to study their reaction mechanism in solution. The results demonstrate that the reaction of tetranuclear [VS₄–Cu₃] and Cu(PPh₃)Cl in CDCl₃ successively yields penta-, hexa- and hepta-nuclear V–Cu–S heterometallic clusters when the mole ratio of [VS₄–Cu₃] to Cu(PPh₃)Cl is decreased, and the process can be reversed when [VS₄–Cu₃] is added to [VS₄–Cu₆] gradually. Theoretical calculations were also carried out to explain the experimental results.     

Synthesis and study of η5-C5H5-3,1,2-MIIIC2B9H11−n F n (M = Co,Fe;n = 1−4)

B-Flourosubstituted cyclopentadienyldicarbollylcobalt and -iron were synthesized. Electrochemical studies of iron ⁵-C₅H₅-3,1,2-FeC₂B₉H_11–n F _n (n = 2–4) complexes were carried out.¹⁹F NMR, UV, and IR spectra of the cobalt and iron complexes were obtained.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2984–2989, December, 1996,     

Li2Mg(ZrF6)2 · 4H2O: Synthesis, X-ray crystallographic, thermal, and MAS NMR study

A new zirconate with lithium and magnesium cations of composition Li₂Mg(ZrF₆)₂ · 4H₂O (I) has been synthesized and studied by different methods (X-ray crystallography, differential thermal analysis, IR spectroscopy, and NMR (¹H, ⁷Li, ¹⁹F, including ¹⁹F MAS NMR). The framework structure of I is composed of edge- and vertex-sharing ZrF₈ dodecahedra, Mg(O_w)₂F₄ octahedra, and Li(O_w)F₄ square pyramids. The structure is additionally stabilized by O-H...F and O-H...O hydrogen bonds. Compound is dehydrated in one stage in the temperature range 105–200°C to form Li₂Mg(ZrF₆)₂ (II). The latter undergoes irreversible phase transition at 365°C leading to its decomposition into a mixture of MgZrF₆ (cubic) and Li₂ZrF₆ (hexagonal). According to IR and NMR data, the structure of fluorozirconate chains of compound I is retained after dehydration.     

Computational design and structure-property relationship studies on (I2GaN3) n (n = 1–4) clusters

To look for the single-source precursors, density functional theory calculations were performed to study structures, IR spectra, and stabilities of the possible isomers for the clusters (I₂GaN₃) _n (n = 1–4). It is found that the optimized (I₂GaN₃) _n (n = 2–4) clusters all possess cyclic structure containing Ga-N_α-Ga linkages, and azido group in azides has linear structure. Trends in geometrical parameters with the oligomerization degree n are discussed. The IR spectra are obtained and assigned by vibrational analysis. Thermodynamic properties are linearly correlated with the oligomerization degree n as well as the temperature. Mean-while, the oligomerizations can occur spontaneously at 298.2 K.     

17O, 13C, 1H NMR and IR spectroscopic investigations of (CH3)nC5H5–nRe(CO)3 analogues (n = 0–5)

¹³C, ¹H NMR investigation of the (CH_3nC₅H_5–nRe(CO)₃ Me_nCpReT) n = 0–5 analogous series showed that the signals of almost all magnetic nuclei shift upfield with increase n, which also occurs in (Me_nCp)₂M compounds (M = Fe²⁺, Co³⁺; n = 0–5). The smaller value of the C(CH₃) signal (1.5 ppm.) shifts upfield when a further methyl group is introduced into the vicinal position, this shift can be attributed to the absence of the second methyl cyclopentadienyl ring. It is noteworthy that methyl cyclopentadienyl ring coordination to the transition-metal atom results in the downfield shift of the substituted carbon atom (C_key) signal. One of the reasons for such a shift might be the reduction in screening effect of the central CpM bond π-electron current on C_key owing to nodal properties of Cp ring e-orbitals. The δ ¹³C(CO), δ ¹⁷O(CO), and v(CO) values reflect successive increases of Re → CO π-back donation with increase in n.     

Vibrational spectra,force fields and NMR-data for triorganyl-tetrelomethanes CH4−n(TtR3)n (Tt = Sn and Pb)

Based on vibrational spectra normal coordinate calculations have been carried out for trimethyltetrelomethanes CH_4−n(TtMe₃)_n (Tt = Sn and Pb, n = 2 and 4). The resulting comparable force constants of the two distinguishable types of carbon-metal bonds for Tt = Sn (range K(C-Sn) 220 - 180 Nm⁻¹) are 10 – 15% higher than for Tt = Pb (K(C-Pb) 190 - 170 Nm⁻¹). These force constants K(C-Tt) are similar to the K(C-Hg) values of corresponding methylmercuriomethanes CH_4−n(HgMe)_n. The force constants K (C-Tt), and also the coupling constants ¹J(Tt,C) from NMR spectra, indicate weakening of the carbon-metal bonds in the central CTt_n groups with growing n, whereas the peripheral TtMe bonds are almost unaffected by variations of n.     

New methods of preparation of hydroxy-closo-decaborates [B10H10 − n (OH) n ]2− (n = 1, 2)

New methods of preparation of hydroxy-closo-decaborates [B₁₀H_{10 ? n} (OH) _n ]^2? (n = 1, 2) that are based on the reaction of anions [B₁₀H_{10 ? n} (OAc) _n ]^2? and alkoxyethylidenoxonio-closo-decaborates [2-B₁₀H₉OC(OR)CH₃]^? with aqueous solution of hydrazine are proposed. The obtained compounds were characterized by IR, ESI/MS, and NMR (¹H, ¹¹B, ¹³C) spectroscopy.     

Synthese und spektroskopische charakterisierung von cyclopentadienyleisen-komplexen mit PN-liganden des typs (C6H5)3−nP(NR2)n (n = 0−3; R = CH3, C2H5

The complex cations [C₅H₅Fe(CO)₂L]BF₄ (L = (C₆H₅)_3−nP(NR₂)_n; n = 0−3 R = CH₃, C₂H₅) have been obtained from the reaction of [C₅H₅Fe(CO)₂THF]BF₄ (I) with L. The reaction of I with E(NR₂)₃ (E = As, Sb; R= CH₃) is also described. Spectroscopic investigations (IR, ¹H, ¹³C and ³¹P NMR) indicate an increase in electron density on the iron center through increase of the number of P-bound NR₂ groups.     

簇合物(F2GaN3)n(n=1～4)的理论研究

采用密度泛函理论B3LYP/6-311+G*方法,计算研究了(F2GaN3)n(n=1～4)簇合物的结构和性质.研究表明,簇合物(F2GaN3)n(n=2～4)的优化构型均拥有Ga-Na-Ga连接的环状结构.讨论了几何参数随聚合度的变化关系.三聚体的船式构象较椅式构象的能量低16 kJ·mol-1,具有S4对称性的四聚...     

Negative ion photoelectron spectroscopy of solvated electron cluster anions, (H2O) n − and (NH3) n −

The photodetachment spectra of (H₂O) _n ^=2?69/? and (NH₃) _n ^=41?1100/? have been recorded, and vertical detachment energies (VDEs) were obtained from the spectra. For both systems, the cluster anion VDEs increase smoothly with increasing sizes and most species plot linearly withn ^?1/3, extrapolating to a VDE (n=∞) value which is very close to the photoelectric threshold energy for the corresponding condensed phase solvated electron system. The linear extrapolation of this data to the analogous condensed phase property suggests that these cluster anions are gas phase counterparts to solvated electrons, i.e. they are embryonic forms of hydrated and ammoniated electrons which mature with increasing cluster size toward condensed phase solvated electrons.     

Syntheses and X-ray Characterization of Novel [M4(H2O)2(XW9O34)2] n− (M=CuII, X=CuII; and M=FeIII, X=FeIII) Polyoxotungstates

Two novel examples of sandwich type heteropolyanions were synthesized and characterized by X-ray crystal structure and elemental analysis as well as infrared spectroscopy. Na₁₃[H₃Cu₄(H₂O)₂(CuW₉O₃₄)₂]39H₂O (1) and Na₉K[Fe₄(H₂O)₂(FeW₉O₃₄)₂]32H₂O (2) were prepared in aqueous solution by reaction of sodium tungstate with Fe^III and Cu^II cations, respectively. 1 crystallizes in the monoclinic space group P2₁/n (a=13.054(3) Å, b=17.729(4) Å, c=20.998(4) Å, =93.50(3)°), while 2 is triclinic, space group P¯1 (a=12.316(2) Å, b=13.716(3) Å, c=14.925(3) Å, =99.36(3)°, =104.21(3)°, =101.55(3)°). Each anion consists of two [XW₉O₃₄] ^n– moieties (X=Fe^III, n=11 (1) and Cu^II, n=12 (2)) which can be described as -B-isomers of the defect Keggin anion. These units are linked via a belt of four Fe^IIIO₆ or Cu^IIO₆ groups. Two transition metal atoms fill their octahedral coordination sphere with one additional water ligand.     

Interactions between Ni n (n = 1–4) clusters and molecules of methane,water, and hydrogen peroxide

Quantum chemical computations and study of IR spectra of systems Ni₄ + CH₄, Ni₄ + H₂O, and Ni₄ +H₂O are performed. The results are discussed conjointly with analogous data for products of reactions with Ni _n (n=1–3). It is shown that formation of complexes with either hydrogen atoms or CH₃ and OH radicals in a bridged position is characteristic of these systems. It is essential that the ground state of the nickel frame formed in Ni₄ systems has the form of a flat rhombus, which is different from the main isomer form of Ni₄ having pyramidal structure.     

Fluorinated Mono and Spirocyclic Δ5[sgrave]5P and Δ5[sgrave]6P Derivatives of (HO)3−nHnPO (n= 0−3)

Abstract

The properties of PF₅, HPF₄, H₂PF₃, and H₃PF₂ (Δ⁵[sgrave]⁵P derivatives of (HO)₃PO, (HO)₂HPO, (HO)H₂PO, and of the hypothetic H₃PO) and the formation of the related Δ⁵[sgrave]⁶P anions PF₆ ^–, HPF₅ ^–, and trans-H₂PF₄ ^– have been studied some years ago ^1–4. The mono and spirocyclic dioxa and tetraoxa analogues, 1 and 2 available from the corresponding precursor phosphoranes by fluoride addition could be found also as products in the reaction of phosphite 3⁵ and K⁺(CF₃)₂CFO^– together with two other phosphates, 4 and 5. A ¹⁹F–¹⁹F homocorrelated 2 D NMR spectrum of 2 indicated coupling of the P–F fluorine nuclei with two CF₃ groups by a non bond mechanism.     

Synthesis,characterization and 1H NMR studies of [Co(en)2(malH)2]ClO4·H2O

The trans-[Co(en)₂(malH)₂]ClO₄·H₂O complex was prepared by the reaction of sodium hydrogen malonate with [Co(en)₂(H₂O₂](ClO₄)₃ in the presence of a large concentration of perchlorate ion. It showed a three-band visible spectrum (γγ_max 357, 448 and 542.6 nm), diagnostic of a trans-MA₄B₂ system and gave characteristic IR bands as expected for a trans-bisethylenediamine cobalt(III) complex. The ¹H NMR spectrum in DMSO-d₆ revealed a broad band at 5.8 ppm assignable to the amino hydrogen and a single band at 2.68 for the ethylene group of the chelate ring. The

group of the hydrogen malonate ion appeared as a sharp singlet at 2.95 ppm and integration showed the presence of two bimalonate groups. The reactive methylene protons were found to be exchangeable. Ion association by counter ions of the complex ion in DMSO-d₆ showed no preference among amino protons. This is as expected for trans complexes with D_2h-symmetry.