Synthesis of organophosphorus compounds containing different Y,C,Y-chelating ligands. Crystal structure of P ← N intramolecularly coordinated diselenoxophosphorane

The reactions of L^1-3Li salts containing different Y,C,Y-chelating ligands L¹ = 2,6-(t-BuOCH₂)₂C₆, L² = 2,6-(MesOCH₂)₂C₆ and L³ = 2,6-(Me₂NCH₂)₂C₆ with PCl₃ is reported. While the presence of ligands L^2,3 afforded the synthesis of dichlorophosphines L²PCl₂ (2) and L³PCl₂ (3), the use of ligand L¹ resulted to the isolation of O → P coordinated 1-chloro-7-(t-butoxymethyl)-3H-2,1-benzoxaphosphole (1) as the result of the cyclization type reaction of dichlorophosphines L¹PCl₂. The hydrolysis of compounds 1-3 as well as the preparation of phosphanes L²PH₂ (7), L³PH₂ (8), L²PH(SnMe₃) (9) and L³PH(SnMe₃) (10) is also discussed. The presence of N → P coordination enabled the isolation of N → P coordinated diselenoxophosphorane L³PSe₂ (11). Compounds 1-11 were characterized by the help of multinuclear NMR spectroscopy, ESI mass spectrometry and the structure of compound 11 was established by X-ray diffraction analysis.     

Organo-bridged dicobaloximes: Synthesis, structure and nuclear magnetic resonance study

This short review describes the synthesis and structural characteristics of methylene, xylylene and biphenyl-bridged dicobaloximes. The bridged dicobaloximes are easily synthesized by oxidative alkylation method and the yield of dicobaloxime depends on many factors like reaction time, solvent, dihalide:Co(I) ratio and also on the nature of dihalide used. The NMR and structural studies have been described. The cobalt-bound CH₂ and dioxime protons in xylylene-bridged dicobaloximes become nonequivalent at sub-zero temperature and this is caused by the restricted rotation of the Co-C bond. However, the nonequivalence in biphenyl-bridged dicobaloximes is caused by atropisomerism and/or restricted rotation of C-Ph/Co-C bond. Two cobaloxime units of biphenyl-bridged dicobaloximes are symmetrical, and can be looked at as two independent benzyl cobaloximes and there is no direct or indirect interaction between them. In the xylylene-bridged dicobaloxime, one cobaloxime unit affects the structural parameters of the other unit through axially bridged benzyl group, which is sandwiched between two dioxime wings.     

A family of titanium (IV) alkoxo complexes with N,O and O,O chelating ligands. Crystal structure of [Ti(O-i-Pr)2{2-(−)-menthoxo-pyridine}2]

In view of the wide applicability and versatility of titanium based Lewis acids in selective organic synthesis including asymmetric synthesis, we have synthesized a family of mono and polyatomic titanium derivatives. The polymetallic complexes prepared are bridged by pyridimine, quinone and triazine based ligands. The synthesis of [{Ti(O-i-Pr)₃(Oddbf)}₂] (1), [Ti(O-i-Pr)₂(Oddbf)₂] (2), [{Ti(O-i-Pr)₂(Oddbf)(OMent)}₂] (3) (ddbfO = 2,3-dihydro-2,2-dimethyl-benzofuranoxo; MentO = (1R,2S,5R)-(−)-menthoxo), [{Ti(O-i-Pr)₃(OMenpy)}₂] (4), [Ti(O-i-Pr)₂(OMenpy)₂] (5) (MenpyO = (1S,2S,5R)-(−)-menthoxo-pyridine); [{(Ti(OR)₃)₂L}_n] (RO = isopropoxo, (1R,2S,5R)-(−)-menthoxo) (6-11) and [{(Ti(O-i-Pr)₃)₃L}_n] (12) was accomplished from a Lewis acid such as Ti(O-i-Pr)₄, [{Ti(O-i-Pr)₃(OMent)}₂] or [Ti(OMent)₄] and chelating ligands (ddbfOH = 2,3-dihydro-2,2-dimethyl-benzofuranol; MenpyOH = (1R,2S,5R)-(−)-5-methyl-2-isopropyl-1-(2′-pyridinyl)cyclohexan-1-ol; LH₂ = 4,6-dihydroxy-2,5-diphenyl-pyrimidine, 2,4-dihydroxy-5,6-dimethyl-pyrimidine, 5,8-dihydroxy-1,4-napthoquinone, 2,5-dihydroxy-1,4-benzoquinone and LH₃ = cyanuric acid) that provide a rigid framework for the metal centre. The molecular structure of 5 has been determined by single crystal X-ray diffraction studies.     

Multiple coordination modes of hemilabile 3-dimethylaminopropyl chalcogenolates in platinum(II) complexes: Synthesis, spectroscopy and structures

The reactions of N,N-dimethylaminopropyl chalcogenolates with platinum(II) compounds have been carried out and complexes of the types [PtCl(ECH₂CH₂CH₂NMe₂)]₂ (1) (E = S (1a) and Se (1b)), [Pt(ECH₂CH₂CH₂NMe₂)₂]_n (2) (E = S (2a) and Se (2b)), [(PtCl₂)₂{(Me₂NCH₂CH₂CH₂E)₂}]_n (3), [PtX(SeCH₂CH₂CH₂NMe₂)]₂ (4) (X = SePh (4a) and OAc (4b)) and [PtCl(ECH₂CH₂CH₂NMe₂)(PR₃)]_n (5) (E = S, Se, Te) have been isolated. These complexes have been characterized by elemental analysis, IR, UV-Vis, NMR (¹H, ¹³C, ³¹P, ⁷⁷Se, ¹⁹⁵Pt) spectroscopy and FAB mass spectral data. The structures of [PtCl(SeCH₂CH₂CH₂NMe₂)]₂ (1b) and [PtCl(SCH₂CH₂CH₂NMe₂)(PPr₃)]₂ (5a) have been established by single crystal X-ray diffraction data. Both the molecules have dimeric structures. In 1b, two platinum atoms are held together by symmetrically bridging Se atoms of the chelating selenolate groups. In 5a, two thiolates form a four-membered Pt₂S₂ bridge with dangling NMe₂ groups.     

Synthesis of Me2LSn(o-CH3-C2B10H10): Crystal structure of Sn ← O intramolecularly coordinated organotin compound containing 1-methyl-o-carborane

The synthesis and molecular structure of Me₂LSn(1-Me-1,2-C₂B₁₀H₁₀) (3), L is 2,6-(t-BuOCH₂)₂C₆H₃⁻, the precursor for the synthesis of other Sn ← O intramolecularly coordinated organotin(IV) compounds containing 1-methyl-o-carborane (1-Me-1,2-C₂B₁₀H₁₁) is reported. Compound 3 was characterized by the help of ¹H, ¹¹B, ¹³C, ¹¹⁹Sn NMR spectroscopy and X-ray diffraction technique. For the preparation of 3, a novel triorganotin(IV) compound Me₂LSnCl (2) has been prepared since the reaction of sterically more demanding Ph₂LSnCl (1) with 1-Me-1,2-C₂B₁₀H₁₀Li did not occur.     

Synthesis and characterization of a series of diphenyldipyrazolylmethane complexes with zinc(II)

The zinc(II) coordination chemistry of a series of diphenyldipyrazolylmethane ligands was explored using ¹H NMR and single crystal X-ray diffraction. Unsubstituted diphenyldipyrazolylmethane (dpdpm), diphenylbis(3-methylpyrazolyl)methane (dpdp′m), and diphenylbis(3,5-dimethylpyrazolyl)methane (dpdp″m) were reacted with Zn(NO₃)₂ to afford Zn(dpdpm)(NO₃)₂, Zn(dpdp′m)(NO₃)₂ and Zn(Pz″)₂(NO₃)₂ where Pz″ = 3,5-dimethylpyrazole, respectively. All attempts to isolate Zn(dpdp″m)(NO₃)₂ with the intact dpdp″m ligand were unsuccessful due to decomposition of the ligand. These bidentate ligands support the formation of 1:1 ligand to metal complexes and structurally model the two histidine coordination mode common in zinc proteins.     

Synthesis, crystal structure and characterization of alkali metal hydroxoantimonates

Several alkali metal hydroxoantimonates, K₂[Sb(O)(OH)₅], Na[Sb(OH)₆], Cs[Sb(OH)₆] and Cs₂[Sb₂(μ-O)₂(OH)₈] were isolated from aqueous solutions and characterized by single crystal and powder X-ray diffraction studies and by FTIR and thermal analysis. Crystal structures involving [Sb(O)(OH)₅]²⁻ were never anticipated before, and this is also the first disclosure of a dinuclear antimonate [Sb₂(μ-O)₂(OH)₈]²⁻. Aqueous antimonate solutions of different pH were studied by high resolution electrospray mass spectrometry showing pH indifferent spectra and predominance of the mono and dinuclear antimonate species at pH 4-10.     

Synthesis and characterisation of isomeric cycloaurated complexes derived from the iminophosphorane Ph3PNC(O)Ph

Using different organomercury substrates, two isomeric cycloaurated complexes derived from the stabilised iminophosphorane Ph₃PNC(O)Ph were prepared. Reaction of Ph₃PNC(O)Ph with PhCH₂Mn(CO)₅ gave the manganated precursor (CO)₄Mn(2-C₆H₄C(O)NPPh₃), metallated on the C(O)Ph substituent, which yielded the organomercury complex ClHg(2-C₆H₄C(O)NPPh₃) by reaction with HgCl₂ in methanol. Transmetallation of the mercurated derivative with Me₄N[AuCl₄] gave the cycloaurated iminophosphorane AuCl₂(2-C₆H₄C(O)NPPh₃) with an exo PPh₃ substituent. The endo isomer AuCl₂(2-C₆H₄Ph₂PNC(O)Ph) [aurated on a PPh₃ ring] was obtained by an independent reaction sequence, involving reaction of the diarylmercury precursor Hg(2-C₆H₄P(NC(O)Ph)Ph₂)₂ [prepared from the known compound Hg(2-C₆H₄PPh₂)₂ and PhC(O)N₃] with Me₄N[AuCl₄]. Both of the isomeric iminophosphorane derivatives were structurally characterised, together with the precursors (2-HgClC₆H₄)C(O)NPPh₃ and (CO)₄Mn(2-C₆H₄C(O)NPPh₃). The utility of ³¹P NMR spectroscopy in monitoring reaction chemistry in this system is described.     

Synthesis, characterization and structure of metallocene dicyanamide complexes

The bis(cyclopentadienyl) complexes [Cp₂Ti(dca)]₂O and Cp₂V(dca)₂ (dca = dicyanamide) have been prepared by reaction of sodium dicyanamide with aqueous solution of titanocene dichloride and vanadocene dichloride, respectively. The X-ray structure analyses of both complexes confirmed monodentate coordination of dicyanamide ligand through the terminal nitrogen atom of cyano group.     

Synthesis and X-ray crystal structure of a polymeric copper(II) complex containing the novel ligand 4,4-(1,4-phenylene)bis[3-phenyl-5-(2-pyridyl)-4H-1,2,4-triazole]

The synthesis and X-ray crystal structure of the complex {[Cu^II(Ph₂PBPT)(bpy)](ClO₄)₂ · 2DMF}_∞ where Ph₂PBPT=4,4^′-(1,4-phenylene)bis[3-phenyl-5-(2-pyridyl)-4H-1,2,4-triazole], bpy=2,2^′-bipyridine and DMF=N,N-dimethylformamide are reported. In this one-dimensional coordination polymer the Cu²⁺ ions are in a distorted octahedral N₆ coordination environment made up of two Ph₂PBPT molecules, each chelating via one pyridine and one triazole nitrogen, and one bpy co-ligand. Within the zig-zag chain thus formed the shortest distance between two metal centres across the Ph₂PBPT ligand is 13.305(3) Å while it is 10.009(3) Å between two chains. This complex represents the first structurally characterised example of a coordination compound incorporating a chelating 4,4^′-bis(4H-1,2,4-triazole) as a ligand.     

Synthesis and characterization of metallatranes with phenyl substituents in atrane cage

A new series of mono- and diphenylsubstituted silatranes and boratranes N(CH₂CH₂O)₂(CHR³CR¹R²O)MZ (M = Si, Z = CH₂Cl, CCPh, H, OMenth, R¹, R², R³ = H, Ph; M = B, Z = nothing, R¹, R², R³ = H, Ph) have been synthesized. Both transalkoxylation and stepwise modification of a preformed metallatrane skeleton were used. The chloromethyl derivatives N(CH₂CH₂O)₂(CHRCHRO)SiCH₂Cl (R = H, Ph) react with tert-BuOK under intramolecular cycle expansion to give 1-tert-butoxy-2-carba-3-oxahomosilatranes N(CH₂CH₂O)(CH₂CH₂OCH₂)(CHRCHRO)SiO^tBu (R = H, Ph). The treatment of boratranes N(CH₂CH₂O)₂(CH₂CR¹R²O)B (R¹,R² = H, Ph) with triflic acid and trimethylsilyl triflate results in the products of electrophilic attack at the nitrogen atom. The molecular structures of four silatranes and one boratrane bearing phenyl groups in the atrane skeleton were determined by the X-ray structure analysis.     

Ruthenium polypyridyl complexes containing the bischelating ligand 2,2′-azobispyridine. Synthesis, characterization and crystal structures

Three ruthenium polypyridyl compounds of structural formula [Ru(apy)(tpy)Lⁿ⁻](ClO₄)_(2−n) (apy = 2,2′-azobispyridine; tpy = 2,2′:6′,2″-terpyridine; L = Cl, H₂O, CH₃CN) (1a-c) were synthesized and crystallized. These complexes were fully characterized by means of 1D and 2D ¹H NMR spectroscopy, as well as mass spectrometry and elemental analysis. Although in theory two isomers are possible, i.e. the one in which the central N atom in tpy is trans to the azo N in apy and the one in which the former is trans to the pyridine N in apy, in all cases only the latter was observed. The molecular structures of the compounds were elucidated by single-crystal X-ray diffraction.     

Synthesis and structural characterization of mixed-ligand silver(I) complexes containing diphosphazanes and bidentate N-donor ligands

The reactions of a self-assembled silver(I) coordination polymer, [Ag₂{μ-PrⁱN(PPh₂)₂}(μ-NO₃)₂]_n (1) with various bidentate N-donor ligands such as DABCO, 2,2′-bipyridyl and 1,10-phenanthroline yield 1-D helices or π-π stacked polymers, depending on the chelate vector of the N-donor ligand. The molecular structures of the resultant complexes, [Ag₂{μ-PrⁱN(PPh₂)₂}(DABCO)(NO₃)₂]_n (2), [Ag₂{μ-PrⁱN(PPh₂)₂}(2,2′-bipy)₂(NO₃)₂] (3) and [Ag₂{μ-PrⁱN(PPh₂)₂}(1,10-phen)₂](NO₃)₂ (4) have been confirmed by single-crystal X-ray diffraction. Complex 2 exists as an infinite helical polymer because of the exo-bidentate nature of DABCO. Complex 3 assumes a 2D grid motif as a result of intermolecular π-π stacking among adjacent bipyridine moieties. The phenanthroline complex 4 exhibits strong inter- and intramolecular π-π stacking interactions.     

New pyridyl modified phosphines: Synthesis and late transition-metal coordination studies

Using a phosphorus based Mannich condensation reaction the new pyridylphosphines {5-Ph₂PCH₂N(H)}C₅H₃(2-Cl)N (1-Cl) and {2-Ph₂PCH₂N(H)}C₅H₃(5-Br)N (1-Br) have been synthesised in good yields (60% and 88%, respectively) from Ph₂PCH₂OH and the appropriate aminopyridine. The ligands 1-Cl and 1-Br display variable coordination modes depending on the choice of late transition-metal complex used. Hence P-monodentate coordination has been observed for the mononuclear complexes AuCl(1-Cl) (2), AuCl(1-Br) (3), RuCl₂(p-cymene)(1-Cl) (4), RuCl₂(p-cymene)(1-Br) (5), RhCl₂(Cp^∗)(1-Cl) (6), RhCl₂(Cp^∗)(1-Br) (7), IrCl₂(Cp^∗)(1-Cl) (8), IrCl₂(Cp^∗)(1′-Cl) (8′), IrCl₂(Cp^∗)(1-Br) (9), cis-/trans-PdCl₂(1-Cl)₂ (10), cis-/trans-PdCl₂(1-Br)₂ (11), cis-PtCl₂(1-Cl)₂ (12) and cis-PtCl₂(1-Br)₂ (13). Reaction of Pd(Me)Cl(cod) (cod = cycloocta-1,5-diene) with either 1 equiv. of 1-Br or the known pyridylphosphines 1′-Cl, 1-OH or 1-H gave the P/N-chelate complexes Pd(Me)Cl(1-Br-1-H) (14)-(17). All new compounds have been fully characterised by spectroscopic and analytical methods. Furthermore the structures of 4, 5, 10 and 16 · (CH₃)₂SO have been elucidated by single crystal X-ray crystallography. A crystal structure of the dinuclear metallocycle trans,trans-[PdCl₂{μ-P/N-{Ph₂PCH₂N(H)}C₅H₄N}]₂ · CHCl₃, 18 · CHCl₃, has also been determined. Here 1-H bridges, using both P and pyridyl N donors, two dichloropalladium centres affording a 12-membered ring with the PdCl₂ units adopting a head-to-tail arrangement.     

Synthesis and structure of a hafnium silylamide complex and the chemical vapor deposition of HfxSi1−xO2 films

The complex Hf[N(SiMe₂H)₂]₄ was synthesized, structurally characterized, and used as a precursor with oxygen to prepare hafnium silicate thin films at substrate temperatures ?500 °C in a low-pressure CVD process. The as-deposited films were amorphous, and they remained amorphous upon annealing up to 1100 °C.     

Synthesis and X-ray crystal structure determination of a useful Pd starting compound, enPd(NO3)2

Dinitrato(ethylenediamine)palladium(II) has been crystallized from aqueous solution following treatment of enPdCl₂ with AgNO₃. The en ligand is chelating and the two nitrate ligands bind monofunctionally. When brought in water, the nitrates are immediately replaced by water ligands, thus providing a convenient source of highly reactive [enPd(H₂O)₂]²⁺. ¹H NMR spectra of the title compound in dimethylformamide and acetonitrile indicate proton exchange between NH₂ groups of en ligands.     

Hexanuclear copper(II) complex of a novel poly(pyridine) ligand exhibiting unique long distance ferromagnetic interactions through a nitrato-O,O bridge

A novel hexanuclear copper complex [Cu₆(NO₃)₁₂(opytrizediam)₂(H₂O)][(CH₃)₂CO]_0.5(CH₃CH₂CH₂OH)_0.5 (1) with a NO₃ bridge has been synthesized by reaction of Cu(NO₃)₂ · 3H₂O with the new potentially octadentate ligand opytrizediam in n-propanol/acetone solution (opytrizediam=N,N^′-{2,4-di[(di-pyridin-2-yl)amine]-1,3,5-triazine} ethylenediamine). A single-crystal X-ray diffraction analysis showed the presence of six structurally different copper centres. The coordination spheres of four copper(II) ions are best described as square-pyramidal CuN₂O₃ chromophores while the two other copper(II) ions are in a trigonal-bipyramidal CuN₄O environment. Variable-temperature studies on 1 revealed a unique ferromagnetic coupling of two copper(II) ions bridged by a didentate nitrate anion and separated by a distance of 6.391(6) Å, with J=8.6(1) cm⁻¹.     

X-ray structure and magnetic properties of dinuclear and polymer iron(II) complexes

Five new octahedral iron(II) complexes [FeL2(4-dpa)]_n(EtOH) (1), [FeL2(bipy)]_n(DMF) (2), [FeL1(bpee)]_n (3), [Fe₂L3(1-meim)₄](1-meim)₄ (4) and [FeL1(DMAP)₂] (5), with L1 and L2 being tetradentate coordinating Schiff base like ligands (L1 = (E,E)-[{diethyl-2,2′-[1,2-phenylenebis(iminomethylidyne)]bis[3-oxobutanato](2-)-N,N′,O³,O³′}, L2 = (3,3′)-[{1,2-phenylenebis(iminomethylidyne)]bis(2,4-pentane-dionato)(2-)-N,N′,O²,O²′}) and L3 being a octadentate dinucleating coordinating Schiff base like ligand ({tetraethyl-(E,E,E,E)-2,2′,2′′,2′′′-[1,2,4,5-phenylentetra(iminomethylidine)]tetra[3-oxobutanoato](2-)-N,N′,N′′,N′′′,O³,O³′,O³′′,O³′′′}); 4-dpa = di(4-picolyl)-amine, bipy = 4,4′-bipyridine, bpee = trans-1,2-bis(4-pyridyl)ethylene, 1-meim = 1-methylimidazole and DMAP = 4-dimethylaminopyridine, have been synthesized and characterised using X-ray structure analysis and T-dependent susceptibility measurements. Both methods indicate that all iron(II) centres are in the paramagnetic high-spin state over the whole temperature range investigated. The O-Fe-O angle, the so called bit of the equatorial ligand, is with an average of 111° in the region typical for high-spin iron(II) complexes of this ligand type. In the case of compound 1 an infinite two-dimensional hydrogen bond network can be found, for the compounds 2-4 no hydrogen bond interactions are observed between the complex molecules. A comparison of the curve progression obtained from the magnetic measurements of the mononuclear complex 5 and the polymeric complexes 1-3 leads to the conclusion that no magnetic interactions are mediated over the bridging axial ligands. For the dinuclear complex 4 weak antiferromagnetic interactions between the two iron centres are found.     

Synthesis, characterizations and crystal structures of antimony(III) complexes with nitrogen-containing ligands

Six antimony adducts with N-donor neutral ligands (1,10-phenanthroline, 4,4′-bipyridine) have been obtained following the reaction of antimony halides with phenanthroline and 4,4′-bipyridine. By changing the solvent and stoichiometry, we obtained six different complexes, Sb(phen)Cl₃ (1), Sb(phen)Br₃ (2), Sb₂(phen)₄Br₈ (3) and Sb(bpy)Cl₃ (4), Sb(bpy)₂Cl₃ (5), Sb(bpyH · bpyH₂)Br₆ (6) (where phen = 1,10-phenanthroline, bpy = 4,4′-bipyridine). All the complexes have been characterized via elemental analysis, FT-IR and NMR (¹H, ¹³C) spectroscopy. The crystal structures of complexes 2, 3 and 6 have been determined by X-ray single crystal diffraction.The structural analysis show that the coordination sphere around antimony atom in complex 2 is a distorted square pyramid, coordinated by three bromine atoms and two nitrogen atoms from phen. In complex 3, the central antimony atom is six-coordinated through four bromine atoms and two nitrogen atoms forming a distorted octahedral geometry. Besides that, there are also uncoordinated 1,10-phenanthroline bonded by hydrogen bonds and π-π stacking interactions, which is rarely observed in previous reports. The crystal structure of complex 6 consists of bpyH · bpyH₂ trications and hexabromoantimonate trianions. The antimony atom in the anion has a distorted octahedral environment. Additionally, all complexes present a 3D framework built up by N-H?Br, C-H?Br and C-H?Cl weak hydrogen bonds interactions.     

Zinc(II) chlorido complexes of protonated kinetin and its derivatives: Synthesis, properties and X-ray structure of [Zn(Hkinetin)Cl3]·kinetin

The syntheses and characterization of five novel zinc(II) complexes with protonated kinetin (6-furfurylaminopurine) and its derivatives are described. Based on the results following from elemental analyses (C, H, N), FTIR, Raman, ¹H and ¹³C NMR spectroscopy, conductivity measurements, thermogravimetric (TG) and differential thermal analyses (DTA), and single crystal X-ray analysis, the complexes of the general composition [Zn(HLⁿ)Cl₃]·xLⁿ (1-5) have been prepared, where L¹ = kinetin (6-furfurylaminopurine), L² = 6-(5-methylfurfurylamino)purine, L³ = 2-chloro-6-furfurylaminopurine, L⁴ = 2-chloro-6-(5-methylfurfurylamino)purine and L⁵ = 2-chloro-6-furfurylamino-9-isopropylpurine, and x = 1/2-2. The structure of [Zn(HL¹)Cl₃]·L¹ (1) has been determined by single crystal X-ray analysis. The Zn(II) atom is tetrahedrally coordinated by three chlorido ligands and one N3-protonated organic molecule forming a ZnCl₃N donor set. The organic ligand L¹ is coordinated to the Zn(II) centre through the N7 atom of the purine moiety. NMR spectroscopic study confirmed the N3 and N7 atom to be the protonation, and coordination site, respectively.