SYNTHESIS,CHARACTERIZATION, AND REACTIONS OF MONOMERIC TITANIUM COMPLEXES CONTAINING A CHELATING BIS(PHENOLATE) LIGAND [1, 2]

Abstract

The synthesis of Ti(iso)Cl₂ (iso = the dianion of 2, 2′-ethylidenebis(4, 6-di-rert-butylphenol)) is described. Metathesis reactions of this complex with Grignard reagents, as well as alkali metal salts, yielded Ti(iso)X₂ (X = CH₃, CH, Ph, CH₂SiMe₃, OCMe₃, or NMe₂). Reactions of the Ti-C bond in Ti(iso)(CH₃)₂ toward halogens, active hydrogen compounds, and acetone were studied. In addition. Ti(iso)(X)(Y) (X = CI or CH₃; Y = OC₆H₂-2, 6-^tBu₂-4-Me) could be prepared with the formation of only one coordination isomer. The new complexes have been thoroughly characterized by ¹H and ¹³C NMR spectroscopies. The solid state structure of Ti(iso)Cl₂ was determined via single crystal X-ray diffraction methods. The complex is monomeric, with approximately tetrahedral geometry about the titanium ion. The structure of Ti(iso)Cl₂ is compared to that of Ti(ultra)Cl₂ (ultra = the dianion of 2, 2′-mefhylenebis(6-tert-butyl-4-mefhylphenol)), which was redetermined to greater precision.     

Erste Reaktionen an der P=C- und an der P–P-Bindung des neuen P-Phosphanylphosphaalkens 1-Bis(trimethylsilyl)methyliden-2,2-diisopropyldiphosphan

The New P -Phosphanylphosphaalkene 1-Bis(trimethylsilyl)methylidene-2,2-diisopropyldiphosphane: First Reactions at its P=C and P–P Bonds (Me₃Si)₂C=PCl ( 1 ) reacts with the trichlorosilylphosphanes RR′PSiCl₃ (R and R′ = t-Bu or i-Pr) providing the new P-dialkylphosphanylphosphaalkenes (Me₃Si)₂C=P–P-i-Pr₂ ( 2 ) and (Me₃Si)₂C=P–P(t-Bu)(i-Pr) ( 3 ) as well as the known (Me₃Si)₂C=P–P-t-Bu₂ ( 4 ). The P=C double bond of 2 can be protected reversibly by a [2 + 4]-cycloaddition with cyclopentadiene resulting in the formation of a P-phosphanyl-phosphanorbornene derivative 5 . The [2 + 4]-cycloaddition of 2 with 2,3-dimethylbutadiene provides the cyclic diphosphane 6 . Reactions of 2 with sulfur and selenium were followed by ³¹P and ⁷⁷Se nmr: Chalcogen insertion into the P–P bond leads to the products (Me₃Si)₂C=P–X–P-i-Pr₂ 9 a (X = S) and  9 b (X = Se). Subsequent σ³λ³ → σ⁴λ⁵ oxidation steps of 9 a with S and of 9 b with Se lead to compounds (Me₃Si)₂C=P–X–P(=X)-i-Pr₂ 10 a (X = S) and 10 b (X = Se), which contain phosphinic acid functions with the phosphaalkene moieties attached to S or Se. 10 a and 10 b were not isolated in a pure state. However, trapping 10 b from an enriched solution by [2 + 4]-cycloaddition with cyclopentadiene allowed the isolation of the P-diseleno-phosphinato-phosphanorbornene 12 . The constitution of new compounds 2 , 3 , 5 , 6 and 12 was confirmed by elemental analyses, nmr and mass spectra. The structures of cycloadducts 5 and 6 were determined by X-ray diffraction analysis.     

The Unanticipated Dimerization of Ce@C2v(9)‐C82 upon Co‐crystallization with Ni(octaethylporphyrin) and Comparison with Monomeric M@C2v(9)‐C82 (M = La,Sc, and Y)

We report that Ce@C_2v(9)‐C₈₂ forms a centrosymmetric dimer when co‐crystallized with Ni(OEP) (OEP = octaethylporphyrin dianion). The crystal structure of {Ce@C_2v(9)‐C₈₂}₂?2[Ni(OEP)]?4 C₆H₆ shows that a new C?C bond with a bond length of 1.605(5) Å connects the two cages. The high spin density of the singly occupied molecular orbital (SOMO) on the cage and the pyramidalization of the cage are factors that favor dimerization. In contrast, the treatment of Ni(OEP) with M@C_2v(9)‐C₈₂ (M = La, Sc, and Y) results in crystallization of monomeric endohedral fullerenes. A systematic comparison of the X‐ray structures of M@C_2v(9)‐C₈₂ (M = Sc, Y, La, Ce, Gd, Yb, and Sm) reveals that the major metal site in each case is located at an off‐center position adjacent to a hexagonal ring along the C₂ axis of the C_2v(9)‐C₈₂ cage. DFT calculations at the M06‐2X level revealed that the positions of the metal centers in these metallofullerenes M@C_2v(9)‐C₈₂ (M = Sc, Y, and Ce), as determined by single‐crystal X‐ray structure studies, correspond to an energy minimum for each compound.     

Preparation of 1,2- and 1,4-dihydro derivatives of 6,7-dimethyl-2,3-diphenylquinoxaline via its dianion formed by reductive metallation

Treatment of 6,7-dimethyl-2,3-diphenylquinoxaline with sodium in tetrahydrofuran formed a monomeric dianion. The chemical behavior of this dianion was investigated by a variety of reagents. As the result, alkylation reactions gave 1,2-dihydro derivatives, while acylation reactions occured at 1,4-positions. Annulation of the pyrazine ring system was accomplished by treating the dianion with oligomethylene dichlorides, Cl(CH₂) _n Cl, n = 2–4.     

Quantum-Chemical Calculations of Ruthenium Nitrosyl Complexes with Tetradentate Macrocyclic Ligands

The geometric structure of the ground state and of metastable isomers of nitrosyl complexes trans-[Ru(P)(NO)(Cl)] (P = porphinate dianion) and trans-[Ru(NO)(salen)(X)]^q [salen = N,N'-ethylenebis(salicylideniminate) dianion; X = Cl^- (q = 0), H₂O (q = +1)] was optimized within the framework of the density functional method (SVWN/LanL2DZ+6-31G). The local minima corresponding to metastable isomers with a linear NO coordination through the oxygen atom and with a side ² NO coordination were found on the potential energy surfaces of these compounds. The second metastable states of all the three complexes have a lower energy. The difference in energies between the stable and metastable isomers is the least in the case of the complex trans-[Ru(NO)(salen)(Cl)].     

Electronic Spectra of Ruthenium Nitrosyl Complexes with Macrocyclic Ligands

Electronic spectra of ruthenium(II) nitrosyl complexes [Ru(NO)(salen)(X)]⁴ⁿ (X = Cl, H₂O; n = 0, 1) and [Ru(NO)(P)(ONO)] with tetradentate -conjugated ligands N,N'-ethylenebis(salicylideniminato) dianion (salen) and porphinate dianion (P) were calculated by the TD DFT and CINDO/CI methods. The data obtained were compared to the results of previous calculations of the spectra of trans-[Ru(NO)(NH₃)₄(L)]^{3 +} complexes with nitrogen-containing heterocyclic ligands L. It was found that charge-transfer transitions to * orbitals of the RuNO group dominate in the long-wave part of the spectrum irrespective of the other ligands.     

Reduced Arene Complexes of Scandium

Alkali metal naphthalenide or anthracenide reacted with scandium(III) anilides [Sc(X){N(tBu)Xy}₂(thf)] (X=N(tBu)Xy ( 1 ); X=Cl ( 2 ); Xy=C₆H₃-3,5-Me₂) to give scandium complexes [M(thf)_n][Sc{N(tBu)Xy}₂(RA)] (M=Li–K; n=1–6; RA=C₁₀H₈²⁻ ( 3-Naph-K ) and C₁₄H₁₀²⁻ ( 3-Anth-M )) containing a reduced arene ligand. Single-crystal X-ray diffraction revealed the scandium(III) center bonded to the naphthalene dianion in a σ²:π-coordination mode, whereas the anthracene dianion is symmetrically attached to the scandium(III) center in a σ²-fashion. All compounds have been characterized by multinuclear, including ⁴⁵Sc NMR spectroscopy. Quantum chemical calculations of these intensely colored arene complexes confirm scandium to be in the oxidation state +3. The intense absorptions observed in the UV/Vis spectra are due to ligand-to-metal charge transfers. Whereas nitriles underwent C−C coupling reaction with the reduced arene ligand, the reaction with one equivalent of [NEt₃H][BPh₄] led to the mono-protonation of the reduced arene ligand.     

A NEW METHOD OF PREPARATION OF IRON(II) PORPHYRIN COMPLEXES — ISOLATION AND CHARACTERIZATION OF BIS(N-BUTYLAMINE) IRON(II) PORPHYRIN

Abstract

Fe(II)T(p-X)PP(NH₂Bu ⁿ )₂ (X = H, Cl, CH₃, OCH₃, TPP = dianion of meso-tetraphenylporphyrin) complexes have been prepared by the reduction of Fe(III) porphrins with n-butylamine in antiformin/dichloromethane in air, and by sodium borohydride reduction. The complexes were characterized by electronic and IR spectra and elemental analysis.     

Preparation of 1,2- and 1,4-dihydro derivatives of 6,7-dimethyl-2,3-diphenylquinoxaline <Emphasis Type="Italic">via</Emphasis> its dianion formed by reductive metallation

Treatment of 6,7-dimethyl-2,3-diphenylquinoxaline with sodium in tetrahydrofuran formed a monomeric dianion. The chemical behavior of this dianion was investigated by a variety of reagents. As the result, alkylation reactions gave 1,2-dihydro derivatives, while acylation reactions occured at 1,4-positions. Annulation of the pyrazine ring system was accomplished by treating the dianion with oligomethylene dichlorides, Cl(CH₂) _n Cl, n = 2–4. Correspondence: Seniz Kaban, Department of Chemistry, Yildiz Technical University, Davutpasa Campus, Esenler-Istanbul 34220, Turkey.     

Homometallic Rare‐Earth Metal Phosphinidene Clusters: Synthesis and Reactivity

Two new trinuclear μ₃‐bridged rare‐earth metal phosphinidene complexes, [{L(Ln)(μ‐Me)}₃(μ₃‐Me)(μ₃‐PPh)] (L=[PhC(NC₆H₄iPr₂‐2,6)₂]^?, Ln=Y ( 2 a ), Lu ( 2 b )), were synthesized through methane elimination of the corresponding carbene precursors with phenylphosphine. Heating a toluene solution of 2 at 120 °C leads to an unprecedented ortho C? H bond activation of the PhP ligand to form the bridged phosphinidene/phenyl complexes. Reactions of 2 with ketones, thione, or isothiocyanate show clear phospha‐Wittig chemistry, giving the corresponding organic phosphinidenation products and oxide (sulfide) complexes. Reaction of 2 with CS₂ leads to the formation of novel trinuclear rare‐earth metal thione dianion clusters, for which a possible pathway was determined by DFT calculation.     

Group II Metal Complexes of the Germylidendiide Dianion Radical and Germylidenide Anion

The two‐electron reduction of a Group 14‐element(I) complex [RË?] (E=Ge, R=supporting ligand) to form a novel low‐valent dianion radical with the composition [RË:]^{. 2?} is reported. The reaction of [LGeCl] ( 1 , L=2,6‐(CH?NAr)₂C₆H₃, Ar=2,6‐iPr₂C₆H₃) with excess calcium in THF at room temperature afforded the germylidenediide dianion radical complex [LGe]^{. 2?}?Ca(THF)₃²⁺ ( 2 ). The reaction proceeds through the formation of the germanium(I) radical [LGe?], which then undergoes a two‐electron reduction with calcium to form 2 . EPR spectroscopy, X‐ray crystallography, and theoretical studies show that the germanium center in 2 has two lone pairs of electrons and the radical is delocalized over the germanium‐containing heterocycle. In contrast, the magnesium derivative of the germylidendiide dianion radical is unstable and undergoes dimerization with concurrent dearomatization to form the germylidenide anion complex [C₆H₃‐2‐{C(H)?NAr}Ge‐Mg‐6‐{C(H)‐NAr}]₂ ( 3 ).     

Ruthenium(II) complexes containing bidentate Schiff bases and triphenylphosphine or triphenylarsine

Reactions of ruthenium(II) complexes [RuHX(CO)(EPh₃)₂(B)] (X = H or Cl; B = EPh₃, pyridine (py) or piperidine (pip); E = P or As) with bidentate Schiff base ligands derived by condensingo- hydroxyacetophenone with aniline,o- orp-methylaniline have been carried out. The products were characterized by analytical, IR, electronic and¹H-NMR spectral studies and are formulated as [Ru(X)(CO) (L)(EPh₃)(B)] (L = Schiff base anion; X = H or Cl; B = EPh₃, py or pip; E = P or As). An octahedral structure has been tentatively proposed for the new complexes. The new complexes were tested for their catalytic activities in the oxidation of benzyl alcohol to benzaldehyde.     

Syntheses and X‐Ray Structures of Zinc Amidinate Complexes

Reactions of ZnX₂ (X = Cl, Br) with equimolar amounts of Li[t‐BuC(NR)₂] (R = i‐Pr, Cy) yielded mono‐amidinate complexes [{t‐BuC(NR)₂}ZnX]₂ (X = Cl, R = i‐Pr 1 , Cy 2 ; X = Br, R = i‐Pr 3 , Cy 4 ), whereas reactions with two equivalents of Li‐amidinate resulted in the formation of the corresponding bis‐amidinate complexes [t‐BuC(NR)₂]₂Zn (R = i‐Pr 5 , Cy 6 ). 1 ‐ 6 were characterized by elemental analyses, IR, mass and multinuclear NMR spectroscopy (¹H, ¹³C), and single crystal X‐ray analysis ( 1 , 2 , 3 , 6 ). In addition, the single crystal X‐ray structure of [t‐BuC(NCy)₂]ZnBr·LiBr(OEt₂)₂ 7 , which was obtained as a byproduct in low yield from re‐crystallization experiments of 4 in Et₂O, is reported.     

Zn(II) Heteroleptic Halide Complexes with 2-Halopyridines: Features of Halogen Bonding in Solid State

Reactions between Zn(II) dihalides and 2-halogen-substituted pyridines 2-XPy result in a series of heteroleptic molecular complexes [(2-XPy)₂ZnY₂] (Y = Cl, X = Cl (1), Br (2), I (3); Y = Br, X = Cl (4), Br (5), I (6), Y = I, X = Cl (7), Br (8), and I (9)). Moreover, 1–7 are isostructural (triclinic), while 8 and 9 are monoclinic. In all cases, halogen bonding plays an important role in formation of crystal packing. Moreover, 1–9 demonstrate luminescence in asolid state; for the best emitting complexes, quantum yield (QY) exceeds 21%.     

Substitutionen und oxidative Additionen an 2-Chlor-4, 4, 5, 5-tetrakis(trifluormethyl)-1, 3, 2-dioxaphospholan

Substitution Reactions and Oxidative Addition on 2-Chloro-4, 4, 5, 5-tetrakis (trifluoromethyl)-1, 3, 2-dioxaphospholane Substitution of chlorine in the title compound 1 yields the phosphites XP[OC(CF₃)₂C(CF₃)₂O] ( 2 : X = I, 4 : X = OCH(CF₃)₂, 5 : X = OC(O)CF₃, 7 : X = OSiMe₃). Compound 2 is easily reduced by hydrogen iodide and mercury to give HP[OC(CF₃)₂C(CF₃)₂O], 3 . The acylphosphite 5 decomposes into trifluoracetic acid anhydride and the μ-oxo diphosphite 6 at elevated temperatures. 6 is obtained also in the reaction of triphenylhydroxystannane and 1 , whereas trimethylhydroxystannane formes the phosphonic acid ester 11 which furnishes the phosphoric acid ester 12 upon reacting with hexafluoroacetone. 12 is obtained directly from the monoammonium-salt of hexafluoroacetonehydrate 13 and 1 exhibiting a prototropic rearrangement. Compound 7 is oxidized by chlorine to yield the trichlorophosphorane 9 and the diphosphate 10 . Antimony pentachloride and iodochloride oxidize 1 to give the dichlorophosphonium hexachloroantimonate 14 and the trichlorophosphorane 9 , respectively.     

Isolation of [Rh(diolefin)X2]- species and their reactions with P- or N-donor ligands,tin(II) halides and carbon monoxide

Anionic [Rh(diolefin)X₂]⁻ species (X = Cl, Br) have been prepared and their reactions studied. The reactions with monodentate ligands led to neutral tetracoordinated complexes, and with N-donor bidentate ligands (Rh : LL = 2 : 1) gave Rh(X)(diolefin)(LL), [Rh(diolefin)(LL)]⁺[Rh(diolefin)X₂]⁻, or [Rh(diolefin)(LL)]X compounds, depending on the nature of LL or X. Reactions with carbon monoxide involved diolefin displacement. A trichlorostannato complex was obtained from the [Rh(COD)Cl₂]⁻ species. Reactions of [Rh(COD)Br]₂ with bidentate N-donor ligands were also studied.     

On the mechanism of the conversion of 6-chloropyrido[2,3-B]pyrazine into 1h-lmidazo[4,5-b] pyridine by potassium amide in liquid ammonia

The synthesis of a number of 2-R₁, 3-R₂-6-X-pyrido[2,3-b]pyrazines (1) is reported and their reaction with potassium amide in liquid ammonia investigated. Ring contraction into a 2-R-1H-imidazo[4,5-b]pyridine was found to occur with X = Cl, R₁ = H, R₂ = C₆H₅ (1b); X = Cl, R₁ = R₂ = C₆H₅ ( 1c ); X = Cl, R₁ = H, R₂ = t-C₄H₉ ( 1d ). Besides ring contraction, an increasing amount of dechlorination of 1 was found: 1a , 20%; 1b , 30%; 1d , 40%; 1c , 60%; 1g , 95%. 1e (X = Cl, R₁ = t-C₄H₉, R₂ = H) yields the unreactive anionic σ-adduct at C-3 i.e., 3-amino-2-t-butyl-6-chloro-3,4-dihydropyrido[2,3-b]pyrazine. The ring contraction only proceeds with X = Cl. 1b (X = F) gives an amino-defluorination, 1b (X = Br) exclusively undergoes reductive debromination. The ring contraction of 1a (X = Cl, R₁ = R₂ = H) is investigated by ¹⁵N- and ¹³C-labelling. It is concluded that the conversion into 1H-imidazo[4,5-b]pyridine proceeds via the reactive anionic σ-adduct at C-2, under exclusive elimination of C-2.     

Reactions of 2,5-pyrrolediylbis[N-(o-hydroxyphenylaldimine)] with some metal ions

The novel Schiff-base 2,5-pyrrolediylbis[N-(o-hydroxyphenylaldimine)] (SBH₂) has been synthesized by the condensation of 2,5-pyrroledicarboxaldehyde and o-amino-phenol. The reactions of the Schiff-base with several transition- and post-transition-metal ions have been investigated. The Schiff-base reacts as a tetradentate dianion without deprotonation of the pyrrole. The complexes M(SB)·nH₂O have been isolated and characterized with n = 1, 2 or 3; SB is the dianion of the Schiff-base; and M = divalent Mn, Co, Ni, Cu, Zn, Pd, Cd, Pb or UO₂. The binuclear complexes M(SB)MX₂ for M = Cu, X = NO₃, and M = Ni or Pd, X = Cl, have also been isolated.     

Studies on solid state reactions of coordination compounds. XLVII. Solid state syntheses and crystal structures of cluster compounds {Cu3MoS3I} (PPh3)3S and {Cu3WS3Br} (PPh3)3S

Reactions of [NH⁴]₂[MS₄](M = Mo,W), CuX(X = Br, I) and PPh₃ in the solid state produced four mixed-metal sulfur containing clusters {Cu₃MS₃X}(PPh₃)₃S(M = Mo, W; X = Br, I), two of which (1: M = Mo, X = I; 2: M = W, X = Br) were structurally determined. Crystals of 1 and 2 are triclinic, space group P1 (1: a = 11.895(3), b = 13.107(1), c = 20.473(2)Å, α = 74.95(6), β = 84.87(8), γ = 64.27(7)°, Z=2, V=2776.1 ų, R_w = 0.064 for 6443 observed reflections. 2: a = 11.876 (1), b = 13.065 (2), c = 20.325(2)Å, α = 74.95(1), β= 85.39(1), γ = 64.09(1)°, Z = 2, V = 2737.3ų, R_w = 0.055 for ·5303 observed reflections). The results of the structure determination showed that the central units of the two cubane-like cluster compounds are composed of four metal atoms and four non-metal atoms situated at alternate corners. The differences of cubane-like cluster compounds obtained from solid state reactions and from solution reactions are discussed.     

Reagent control of stereochemistry in allylic additions to chiral aldehydes with CpMo(NO)(X)(2-methallyl) complexes of high enantiomeric purity

Reactions of (R)- and (S)-CpMo(NO)(η³-methallyl)X(X=camphorsulfonate, Cl, Br, I) with chiral α-substituted aldehydes yield homoallylic alcohols with high diastereoselectivity. Reactions of (R)- and (S)-CpMo(NO)(η³- methallyl)L ^S[L^S = (IS)-(+)-10-camphorsulfonate] with D -glyceraldehyde acetonide yield the corresponding homoallylic alcohols in >98% diastereomeric excess. Reactions with racemic 2-phenyl-propionaldehyde and nonracemic 3-benzyloxy-2-methylpropanol are also considered and show that there is very high reagent control of stereo-chemistry in additions to the carbonyl group.