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In our present work we report synthesis of an unsymmetrical diphos ligand, 1-diphenylphosphino-2-di-m-tolylphosphinoethane and its coordinate complexes with group (VI) metal carbonyls such as Cr(CO)6 Mo(CO)6 and W(CO)6. The synthesized ligand and its complexes have been completely characterized by elemental analyses, FTIR, 1HNMR, 31P{1H}NMR and FAB mass spectrometry methods. Special emphasis has been given to calculations of carbonyl force constants. Based on the spectroscopic evidences it has been confirmed that these metal carbonyl complexes with the ditertiary phosphine ligand showed cis geometry in their molecular structure.

Complexes synthesized by reacting alkyl and aryl phosphines with different transition metals are of great inter- est due to their catalytic properties. Many of the phosphine complexes are soluble in polar solvents as a result they find appli- cations in homogeneous catalysis. In our present work we report, four transition metal complexes of Ni(II), Pd(II), Pt(II) and Ru(II) with an asymmetrical ditertiaryphosphine ligand. The synthesized ligand bears a less electronegative substituent such as methyl group on the aromatic nucleus hence makes it a strong σ-donor to form stable complexes and thus could effectively used in catalytic reactions. The complexes have been completely characterized by elemental analyses, FTIR, 1 HNMR, 31 PNMR and FAB Mass Spectrometry methods. Based on the spectroscopic evidences it has been confirmed that Ni(II), Pd(II) and Pt(II) complexes with the ditertiaryphosphine ligand showed cis whereas the Ru(II) complex showed trans geometry in their molec- ular structure.

The peptidyl prolyl isomerase (Pin1) that catalyzes the isomerization of peptide bonds involving proline and phosphorylated serine/threonine/tyrosine and alters the conformation and differential folding has been implicated in the regulation and function of phosphorylated proteins including mitotic and cell cycle proteins viz. Cdc25c, Bcl2, p53 etc. DNA topoisomerase IIalpha is one of the nuclear enzymes that maintain the DNA topology and regulates nuclear transactions like chromatin segregation and mitosis. In the present studies, we have carried out in-silico investigations on the possibilities of pin1 interaction with topo IIalpha and its functional regulation. We found ten potential pin1 interacting sites within topo IIalpha, which were part of loop and/or low complexity regions except helix at S802 within the catalytic domain. Proline directed phosphorylation was found to be possible at 1354, 1361, 1393 positions by cdk. Change in dihedral angle (omega) to 0 degree at all potential pin1 interacting sites at 575, 602, 802 and 950 for cis conformation of peptide bond introduced significant structural change with higher potential energy. All-cis-topo IIalpha structure reveals that potential pin1 sites come closer to each other, perhaps forming a motif, thereby suggesting cooperative phenomenon to maintain higher potential energy conformation. The bio-informatic analysis of topo IIalpha showed that multisite interaction of pin1 is possible at all the predicted sites. However, a strong possibility of pin1 interaction exist within c-terminal at 1213, 1247, 1354, 1361, 1393 sites, which may lead to either alterations in localization or modification in the activity and perhaps stability of the enzyme.

Transfer dehydrogenation of ketones was efficiently carried out in acetone under air by means of a new Ir(III)-cyclometalated pincer type catalyst bearing a robust triptycene-based ligand.

On the basis of the argument that a monochelated octahedral transition-metal unit is topologically analogous to the Type II (cis-dioxo) metal center frequently observed in the structures of many polyoxometalates, we report the synthesis and structural characterization of salts of two polyoxomolybdate anions demonstrating this principle, [{Co(en)}4Mo10O38]4– (1) and [{CoII(H2O)2}{Co(en)}8{Mo20O76}]6– (2). Anion 1 has a structure of nominal Cs symmetry and consists of two blocks of seven edge-shared metal-centered octahedra linked by two corner-shared junctions (Co–O–Mo). The four octahedra which contain {Co(en)}3+ instead of {MoO2}2+ are distributed unequally between the two blocks, three in one and the fourth in the other. The structure of 2 can be described as a chiral macrocyclic assembly (C4 symmetry) of four identical blocks of seven octahedra as observed in the structure of 1, but now containing two {Co(en)}3+ per block. As in 1 the blocks are linked by corner-shared Co–O–Mo linkages. A trans-diaquacobalt(II) cation occupies the center of the anion. The opportunities provided by the introduction of chelated metal centers, especially those with unsymmetrical diamines, into new polyoxometalates include the generation of resolvable and optically stable structures that have so far eluded polyoxometalate chemists.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

The adsorption and dissociation of three carbonyl compounds, formaldehyde, acetaldehyde, and acetone, on the magnesium oxide nanosurface, consisting of four stacked (MgO)3 hexagons, is investigated by first principles density functional theory (DFT). In the case of formaldehyde, strongly chemisorbed species, with carboxylate-like structures, are initially formed. These may subsequently undergo heterolytic cleavage of an aldehyde C-H bond to form formate ions involving a surface oxide ion and a hydride ion adsorbed over the magnesium dication [(MgH+)(HCOO-)]. For acetaldehyde, besides this reaction leading to the formation of acetate, the methyl hydrogen of the adsorbed species also tends to attach itself to a surface oxide ion, yielding surface hydroxyl ions and adsorbed [CH2=C(H)OMg]+. These results are in accord with our previous experimental and theoretical results. In particular, the shift of the aldehyde C-H vibration band to higher frequency and the appearance of OH bands in the infrared spectrum are clearly accounted for. For acetone, the mechanism is found to be similar, i.e., a methyl hydrogen shift to yield surface enolate. Again, this is in agreement with experimental studies.

Infrared and Raman spectra of solid trans-dichloro-bis[diperfluoroethyl(phenyl)phosphine]platinum(II), trans-Pt[PPh(CF3CF2)2]2Cl2, have been studied at high external pressures up to ∼50 kbar with the aid of a diamond-anvil cell. A gradual, pressure-induced phase transition, most probably second order, was observed in the 21–34 kbar pressure range. In the IR spectra, the bands assigned to the C F stretching modes of the CF3 groups exhibit larger pressure sensitivities than do those associated with the C F stretching modes of the CF2 groups, most probably because of their physical location on the outside in the molecules in the unit cell. The fairly high pressure sensitivities of the symmetric Pt Cl stretching mode in both the low and high pressure phases (0.46 and 37 cm−1/kbar, respectively) are considered to reflect the low force constant associated with the long Pt Cl bond length thus making this vibration more susceptible to compression.

A series of different ligands, X, varying from the neutral H 2 O to the strong σ donor, SiH 3 − , has been taken in the complex [PtClX(dms) 2 ] in an effort to rationalize the trans influence of these ligands on the Pt–Cl bond. Several factors have emerged from this study. The first is that the Pt–Cl bond length is highly sensitive to the nature of the ligand opposite to it. There exists a linear relationship between the Pt–Cl bond length and the hardness of the ligand, besides various other linear relationships, such as those with the partial charge densities on the Pt and Cl atoms, the population of the platinum and chlorine orbitals, etc. Some observations regarding the relative strengths of the Pt–S bonds for dms and dmso ligands have also been made.

Homogeneously dispersed bimetallic oxides in nanocrystalline or amorphous forms, of the type MAl2O4 (where M = Mg, Ca, Mn, Co, Fe, and Zn) were prepared from bimetallic oxo-bridged alkoxides [(RO)2Al–O–M–O–Al(OR)2], where the Al–O–M–O–Al bonds were not hydrolytically cleaved. This approach yields hydroxides [(HO)2Al–O–M–O–Al(OH)2] which, upon thermal dehydration, yield oxides [OAl–O–M–O–AlO], such that M is homogeneously dispersed with an empirical formula of MAl2O4. These materials were obtained in high surface area forms and were characterized by X-ray diffraction, electron microscopy, surface area analyses, and solid-state 27Al NMR. Comparative studies of the hydrolysis of alkoxo-bridged alkoxides yielded mixed metal oxide phases with lower surface areas.

The reaction of Re 2 Cl 4 ( μ-dppm ) 2 ( dppm = Ph 2 PCH 2 PPh 2 ) with Tl(acac) affords the bis-acetylacetonate complex Re2Cl2(acac)2(μ-dppm)2 (1) via the intermediacy of Re2Cl3(acac)(μ-dppm)2 (2). These are the first examples of β-diketonate complexes of the electron-rich triple bond. Solutions of 1 in non-aqueous solvents slowly convert to 2, which in the presence of an oxygen source decomposes to Re2(μ-O)(O)2Cl4(μ-dppm)2 and Re2(μ-O)2(O)2Cl4(μ-dppm)2 (3). The single crystal X-ray structures of 1–3 have been determined; the Re–Re distances (in A) are 2.2968(3), 2.2542(5) and 3.1415(7), respectively.

Nanocrystals of Al2O3 and Al2O3/MgO have been produced by a modified aerogel synthesis involving the corresponding aluminum tri-tert-butoxide, magnesium methoxide, toluene, methanol, ethanol, and water. The resulting oxides are in the form of powders having crystallites of about 2 nm or less in dimension. These crystallites have been studied by transmission electron microscopy (TEM), and Brunauer−Emmet−Teller (BET) methods, and were found to possess high surface areas and pore volumes (800 m2/g for Al2O3 and 790 m2/g for Al2O3/MgO, compared to 450 m2/g for MgO). As seen with other metal oxides, once they are produced as nanoparticles, their reactivity is greatly enhanced on a per unit surface area basis. This is thought to be due to morphological differences, whereas larger crystallites have only a small percentage of reactive sites on the surface, smaller crystallites possess much higher surface concentration of such sites per unit surface area. Elemental analysis, X-ray diffraction, and infrared spectro...

Room-temperature reactions of VX, GB, GD, and HD with nanosize Al(2)O(3) (AP-Al(2)O(3)) have been characterized by (31)P, (13)C, and (27)Al MAS NMR. Nerve agents VX, GB, and GD hydrolyze to yield surface-bound complexes of their corresponding nontoxic phosphonates. At sufficiently high loadings, discreet aluminophosphonate complexes, Al[OP(O)(CH(3))OR](3), are generated which are identical to synthesized model compounds. Thus the reaction with phosphonic acids is not just surface-limited, but can continue to the core of alumina particles. HD mainly hydrolyzes at lower loadings to yield thiodiglycol (TG, 71%) and a minor amount of the CH-TG sulfonium ion (12%), although some elimination of HCl is also observed (17%). The reactive capacity for HD is evidently exceeded at high loadings, where complete conversion to TG is hindered. However, addition of excess water results in the quantitative hydrolysis of sorbed HD to CH-TG. On AP-Al(2)O(3) dried to remove physisorbed water, (13)C CP-MAS NMR detects a surface alkoxide consistent with that of TG.

Nanocrystals of MgO, CaO, and Al 2 O 3 were prepared by aerogel (AP-samples) or conventional (CP-samples) methods. High surface areas/gram were obtained, often as high as 500 m 2 /g (1) . These materials were investigated as adsorbents for typical volatile organic compounds that are representative of air pollutants. As a result of their high surface areas and their enhanced surface reactivity, nanocrystalline MgO, CaO and Al 2 O 3 have shown remarkably high capacities to chemically adsorb such organic compounds. Compared to high surface area activated carbon, the most widely used material in this application, our nanocrystalline materials have exhibited higher capacities and the ability to destructively adsorb rather than physisorb these chemicals. FT-IR investigation of acetaldehyde adsorption on AP- and CP-MgO indicates that a multilayer dissociative adsorption took place. Adsorption of other organic compounds was also investigated including acetone, propionaldehyde, benzaldehyde, trimethylacetaldehyde, ammonia, dimethylamine, N-nitrosodiethylamine, and methanol, most of which were found to adsorb well on AP-MgO. In addition, long term air exposure did not have detrimental effects on the adsorption properties of AP-MgO.

The peptidyl prolyl isomerase (Pin1) that induces cis-trans isomerization of the peptide bond involving serine/ threonine-proline has recently been shown to regulate the activity of many phosphoproteins including the ones involved in damage response pathways. We investigated Pin1 as a potential target for enhancing the efficacy of anticancer therapy by studying the effects of juglone, a Pin1 inhibitor on the cytotoxicity of etoposide (a widely used anticancer drug that targets topoisomerase IIα) in human tumor cell lines. Treatment of cells with juglone synergistically enhanced the cytotoxicity of etoposide (loss of clonogenicity) with a tenfold increase when etoposide treatment preceded juglone exposure. On the other hand, the toxicity was less than additive when the treatment protocol was reversed (i.e exposure to juglone followed by etoposide treatment). This suggests that Pin1 inhibition possibly reduces the induction of initial DNA damage by etoposide, which was supported by a decrease in the levels of chromatin bound topoIIα. Increase in the etoposide induced toxicity by juglone appeared to be mainly due to enhanced mitotic cell death linked to cytogenetic damage, although a moderate increase in interphase (apoptotic) death was also evident as revealed by DNA degradation (hypodiploid population and TUNEL assay). Since the level of Pin1 is found to be higher in cancer cells, this enzyme could be a potential target for developing an adjuvant to enhance the efficacy of anticancer therapies.

The peptidyl prolyl isomerase (Pin1) that catalyzes the isomerization of peptide bonds involving proline and phosphorylated serine/threonine/tyrosine and alters the conformation and differential folding has been implicated in the regulation and function of phosphorylated proteins including mitotic and cell cycle proteins viz. Cdc25c, Bcl2, p53 etc. DNA topoisomerase IIalpha is one of the nuclear enzymes that maintain the DNA topology and regulates nuclear transactions like chromatin segregation and mitosis. In the present studies, we have carried out in-silico investigations on the possibilities of pin1 interaction with topo IIalpha and its functional regulation. We found ten potential pin1 interacting sites within topo IIalpha, which were part of loop and/or low complexity regions except helix at S802 within the catalytic domain. Proline directed phosphorylation was found to be possible at 1354, 1361, 1393 positions by cdk. Change in dihedral angle (omega) to 0 degree at all potential pin1 interacting sites at 575, 602, 802 and 950 for cis conformation of peptide bond introduced significant structural change with higher potential energy. All-cis-topo IIalpha structure reveals that potential pin1 sites come closer to each other, perhaps forming a motif, thereby suggesting cooperative phenomenon to maintain higher potential energy conformation. The bio-informatic analysis of topo IIalpha showed that multisite interaction of pin1 is possible at all the predicted sites. However, a strong possibility of pin1 interaction exist within c-terminal at 1213, 1247, 1354, 1361, 1393 sites, which may lead to either alterations in localization or modification in the activity and perhaps stability of the enzyme.

On the basis of the argument that a monochelated octahedral transition-metal unit is topologically analogous to the Type II (cis-dioxo) metal center frequently observed in the structures of many polyoxometalates, we report the synthesis and structural characterization of salts of two polyoxomolybdate anions demonstrating this principle, [{Co(en)}4Mo10O38]4– (1) and [{CoII(H2O)2}{Co(en)}8{Mo20O76}]6– (2). Anion 1 has a structure of nominal Cs symmetry and consists of two blocks of seven edge-shared metal-centered octahedra linked by two corner-shared junctions (Co–O–Mo). The four octahedra which contain {Co(en)}3+ instead of {MoO2}2+ are distributed unequally between the two blocks, three in one and the fourth in the other. The structure of 2 can be described as a chiral macrocyclic assembly (C4 symmetry) of four identical blocks of seven octahedra as observed in the structure of 1, but now containing two {Co(en)}3+ per block. As in 1 the blocks are linked by corner-shared Co–O–Mo linkages. A trans-diaquacobalt(II) cation occupies the center of the anion. The opportunities provided by the introduction of chelated metal centers, especially those with unsymmetrical diamines, into new polyoxometalates include the generation of resolvable and optically stable structures that have so far eluded polyoxometalate chemists.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

The first organotin(IV), aluminium(III)-μ-oxoisoprovides of the type [R3SnOA](OiPr)2] (R = Me or Ph) have been made by heating of trimethyl- or triphenyl-tin acetate with aluminium isopropoxide. The reactions of these μ-oxoisopropoxides with benzoylacetone in 1:1 and 1:2 molar ratios yielded the compounds of the type [R3SnOAl(OiPr)(bzac)] and [R3SnOAl(bzac)2] (where R = Me or Ph and bzac = deprotonated benzoylacetone), respectively.

The yellow complex trans-[PtCl2L2] (L = PPh2CH(SiMe3)2) has been characterised. An attempt to make a similar complex with the more sterically hindered phosphine PPh2C(SiMe3)3 resulted in the loss of a trimethylsilyl group from one phosphine ligand and activation of a CH bond in another to give the white complex PtClPPh2C(SiMe3)2SiMe2CH2{PPh2CH(SiMe3)2}, the structure of which was established by X-ray diffraction.

chemistry Department, Delhi University, Delhi-11 0 007, India E-mail: prameshn@yahoo.com; pnkapoor@himalaya.du.ac.in Chemistry Department, Kurukshetra University, Kurukshetra-136 119, India The chemistry of HMMO (heterobimetallic mixed metal oxide) nanoparticles of the type ABO3 (perovskite), AB2O4 (spinel and antispinel) and AB2O5 (pseudobrookite} has been discussed. Their preparation by the sol-gel route using mixtures of alkoxides, heterobimetallic alkoxides and heterobimetallic-µ-oxo alkoxides are described. Physical and chemical properties, with special reference to high surface area, morphology, crystal structure, catalysis and destructive adsorption studies, along with some important applications have also been discussed.

The novel atrane-like six-coordinate (RO)2TaL complexes [where R ) Me or Et and L ) tris(2-oxy-3,5-dimethylbenzyl)amine] containing three six-membered rings have been synthesized and characterized. The R ) Me complex is the first group 5 representative of this class of compounds structurally characterized by X-ray means. Somewhat surprisingly, these compounds failed to function as single-site initiators for the polymerization of l-LA to isotactic PLA and rac-LA to atactic PLA, whereas Ta(OEt)5 and two titanium analogues ROTiL (where R ) 2,6-di-i-PrC6H3 and i-Pr) as well as Ti(O-i-Pr)4 were effective catalysts for both polymerizations. The tripodal trialkoxy amine ligands made by deprotonating tris(2-hydroxy-3,5-dimethylbenzyl)amine (1) or other 3,5-dialkyl derivatives of 1 have recently been used to make silicon 1 and phosphorus 2 complexes resembling the corresponding atranes (made from triethanolamine) except that the three chelating rings are six- instead of five-membered. The silicon complexes made from deprotonated 1, and some of its derivatives, are more structurally flexible than silatranes themselves, thus allowing for changes in their Si-N bond lengths and 29 Si NMR chemical shifts that are roughly correlated to the electron donating effects of their axial substituents. 2 Recently it was also shown that analogous titanium(IV) complexes of deprotonated 1 and some of its derivatives are catalysts for the syndiospecific polymerization of styrene 3 and in the bulk polymerization of lactide (LA). 4

The original version of the article was published in Cent. Eur. J. Chem. 10(1) (2012), pp 165–171. Unfortunately, the original version of this article contains mistakes in the affiliation section. Dr Devendra D. Pathak’s affiliation is Department of Applied Chemistry, Indian School of Mines, Dhanbad 826 004, India. Dr Pramesh N. Kapoor’s affiliation is Department of Chemistry, University of Delhi, Delhi 110 007, India.

Reaction of the cyclohexyne–platinum(0) complex [Pt(η2-C6H8)(Cy2PCH2CH2PCy2)]* with water and CO2 in the presence of triphenylphosphine gives the bicarbonate salt of the (η1-cyclohexenyl)platinum(II) cation, [Pt(η1-C6H9)(Cy2PCH2CH2 PCy2)(PPh3)] [HCO3] · 3H2O, which has been characterized by n.m.r. spectroscopy and single-crystal X-ray diffraction at low temperature. Crystals are triclinic, space group P1– with unit cell dimensions a 20.315(2), b 12.782(1), c 10.694(1) Å, α 66.61(1), β 104.73(1), γ 102.11(1)˚, and Z 2. The structure was refined to a final R value of 0.036 with use of 7553 reflections [I > 3σ(I)]. The cation has the expected, somewhat distorted planar coordination geometry; the anion consists of discrete, hydrogen-bonded dimers [(HCO3)(H2O)3]22-.

The reactions of niobium and tantalum pentaethoxides withtrans-cinnamic acid (HCA) and dihydrocinnamic acid (HDCA) were carried out in different stoichiometric ratios. The complexes of the type M(OEt)5−n(CA)n and M(OEt)5−n(DCA)n, (n=1, 2 or 3 and M=Nb or Ta) were obtained.

The synthesis of the trans -spanning bidentate diphosphine ligand, 3,3′-oxybis-(di- meta -tolylphosphino)methyl]benzene (I) and its complexes with Ni II , Pd II and Pt II are described. The ligand I forms monomeric trans square planar complexes [MX 2 (I)] (M = Ni, Pd or Pt, X = Cl or X = NCS in case of Ni). 31 P and 1 H NMR parameters are reported.

The bidentate ditertiaryphosphine ligand, bis{3-[bis(3-trifluoromethylphenyl) phosphinomethyl]phenyl} ether (LL) forms monomeric trans-square planar complexes [MX2(LL)] (M = Ni, Pd or Pt, X = Cl; M = Ni, X = NCS) as well as trans-[PtHCl(LL)]; 31P and 1H NMR, and selected IR parameters are reported.

Reaction of dimethyldiacetoxysilane with aluminium isopropoxide was carried out in 1 : 2 molar ratio in refluxing cyclohexane and a mixed [Si(IV), Al(III)] μ-oxo-isopropoxide of the composition Me 2 SiO 2 Al 2 (OPr i ) 4 was isolated. This compound was characterised by elemental analysis and IR and NMR spectral studies. The tertiary butanol derivative, Me 2 SiO 2 Al 2 (OBu t ) 4 , was prepared by alcoholysis. Reactions of this mixed [Si(IV), Al(III)] μ-oxo-isopropoxide with monobasic bidentate carboxylic acids, such as trans -cinnamic acid (HCA) and dihydrocinnamic acid (HDCA) and with dibasic tridentate carboxylic acids such as salicylic acid (H 2 SA) and benzilic acid (H 2 BA) were also studied. Products of the type Me 2 SiO 2 Al 2 (OPr i ) 4- n (L) n [where HL = trans -cinnamic acid (HCA), dihydrocinnamic acid (HDCA) and n = 1,2,3 or 4] and Me 2 SiO 2 Al 2 (OPr i ) 4-2 n (L) n [where H 2 L = salicylic acid (H 2 SA), benzilic acid (H 2 BA) and n = 1 or 2] were isolated and characterised by elemental and spectral studies.

Complexes of the type [XMo(CO) 2 (η 3 -C 3 H 5 )(PP′)] (X  Cl or Br; PP′  R 2 PCH 2 CH 2 PPh 2 ; R = m -FC 6 H 4 ( 1a ), p -FC 6 H 4 ( 1b ), m -CF 3 C 6 H 4 ( 1c )) have been prepared from the reaction of [XMo(CO) 2 (η 3 -C 3 H 5 )(MeCN) 2 ] with the relevant ditertiary phosphines in acetone. From their 1 H NMR and IR data these complexes have been assigned essentially octahedral structures in which the allyl moiety is trans to be unidentate anion, and the two cis -carbonyl groups and two phosphorus donor atoms of the bidentate ligand are approximately coplanar. CO force constants have been calculated.

Iodobenzene adds to the palladium(0) complex Pd(VP)2 (2) (VP = (2-vinylphenyl)diphenylphosphine, o-CH2CHC6H4PPh2) to give the planar palladium(II) complex PdI{o-CH(CH3)C6H4PPh2}{(E)-o-Ph2PC6H4CHCHC6H5} (5), which has been characterized by NMR (1H, 31P) spectroscopy and by single crystal X-ray analysis. Crystals of 5 are triclinic, space group P 1 , a 13.404(5); b 13.850(6), c 14.158(7) A, α 118.39(3), β 92.28(4), γ 95.58(3)°, Z 2; 2139 data with I > 2σ(I) were refined to R 0.087, Rw 0.049. The complex contains a five-membered chelate σ-alkyl group (PdP(1) 2.279(6), PdC(1) 2.05(3) A) and monodentate P-bonded E-(2-styrylphenyl)diphenylphosphine (PdP(2), 2.346(7) A). 5 is believed to be formed by a sequence of oxidative addition, phenyl migration from palladium to one of the vinyl groups, and β-hydride transfer from one P-donor ligand to the other. Bromobenzene reacts with 2 to give the bromo analogue of 5 together with an unidentified minor isomer. Allyl bromide gives PdBr(η3-C3H5)(VP) containing monodentate P-bonded VP, but the products of reaction of 2 with methyl iodide and benzyl bromide have not been fully characterized.

A series of three-coordinate bis(dialkylphosphinomethyl)benzo[c]phenanthrene Ag(I) complexes, alkyl= t-Bu, (1b), and cyclohexyl, (1c), anion = BF4, CIO4, CIO4, NO3, Cl, Br, I, have been prepared and thier 31P-NMR characteristics recorded. The solid state structures of [Ag(1b)Br], [Ag(1b)Cl] and [Ag(1b)CIO4] have been determined by X-ray diffraction. The Ag atom in these complexes shows distorted trigonal geometry. Selected bond lengths and angles are as follows: Ag-P = 2.463(4) A and 2.433(5) A, P-Ag-P=141.6(2)° in the bromo complex, Ag-P = 2.457(2) A and 2.427(2) A, P-Ag-P = 142.6(1)° ion the chloro complex, and Ag-P = 2.394(2) and 2.393 (2) A, P-AG-P = 161.5(1)° in the perchlorato complex.

New complexes of the type cis -[MX 2 (PP′)] (M= Ni, Pd and Pt; X=Cl, Br, I or NCS and PP′=( m - FC 6 H 4 ) 2 PCH 2 CH 2 PPh 2 or ( p -FC 6 H 4 ) 2 PCH 2 CH 2 PPh 2 ) have been synthesized and characterized on the basis of 31 P{ 1 H}NMR 1 H NMR, IR and UV spectroscopy, elemental analysis and magnetic susceptibility measurements. All these complexes are found to be low spin, diamagnetic and square planar. 31 P{ 1 H} spectra of these complexes exhibit extraordinarily large downfield coordination chemical shifts, J ( 31 P 31 P′) and J ( 195 pt 31 P) couplings are discussed. Ring contribution (ΔR) values for palladium and platinum complexes are calculated from 31 P NMR data.

Lanthanide chlorides form adducts of the type [Ln(L)nCl3] (where Ln = La, Pr, Nd, Sm, Eu, when n = 6; and Ln = Gd, Tb, Dy or Yb when n = 5; and L = (EtO)2P(O)H or (PriO)2P(O)H upon interacting with the diethyl and diisopropyl phosphites in dry ethyl and isopropyl alcohol, respectively. Complexes were recrystallised from ethanol or isopropanol and washed with n-hexane. On the basis of elemental analysis, infrared, 1H NMR and 31P NMR spectral studies, it is concluded that these phosphites coordinate to the lanthanide metal atom through the oxygen atom which has the greatest affinity for lanthanides in these adducts.

The first phenylmagnesium carboxylates, C6H5MgOOCR·THF, have been made by reaction of phenylmagnesium bromide with the sodium salt of carboxylic acids [RCOONa {where R = CH3, ClCH2, Cl2CH, Cl3C, CH3CH2, (CH3)2CH, C6H5CH2 and CH3(CH2)3CH2}]. All these derivatives are white or pale yellow solids, soluble in polar solvents. The carboxylates have been characterized by elemental analysis, conductance measurements, and spectral studies (1H NMR and IR). The IR data suggest that carboxylate group acts as a bridging bidentate ligand.

The ditertiary phosphines, 1-diphenylphosphino-2-bis( m -fluorophenyl) phosphinoethane ( 1a ), 1-diphenylphosphino-2-bis( p -fluorophenyl) phosphinoethane ( 1b ), 1-diphenylphosphino-2-bis( m -trifluoromethylphenyl) phosphinoethane ( 1c ) complexes of ruthenium(II) of the type [Ru(PP′) 2 X 2 ] (X = Cl, Br, I, NCS, PP′ = 1a , 1b or 1c ) and [Ru(CO) 2 (PP′)X 2 ] (X = Cl, Br, I) have been prepared and characterized on the basis of elemental analysis, IR, UV, 1 H NMR and 31 P NMR (in a few cases) data. Based on the result of these studies, trans - and cis -octahedral structures for [Ru(PP′) 2 X 2 ] and [Ru(CO) 2 (PP′)X 2 ] complexes, respectively, have been proposed. In all these cases, the ditertiary phosphines act as potential bidentate chelating ligands.

Compounds of the type [M(OPri)m−n(FA)n] (where m = 3 and n = 1 to 3 when M = Al; and m = 4 and n = 1 to 4 when M = Ti) have been synthesised by the reactions of aluminium and titanium isopropoxides with furylacrylic acid (HFA) in benzene. The corresponding tertiary butoxide derivatives, [M(OBut)m−n(FA)n], were also obtained by the alcohol-interchange technique. These compounds have been characterised by elemental analysis, and i.r. and p.m.r. spectra.

Complexes [MX2(1)] (M = Ni, Pd and Pt; X=Cl and NCS; 1 = 2,11-bis(dialkyl-[or diaryl]phosphinomethyl)benzo[c]phenanthrene; alkyl = cyclohexyl t-butyl; aryl = m-tolyl, p-anisyl and m-CF3 C6H4) have been synthesized. An NMR. study of the t-butyl complexes provides evidence for a “fan-like” motion of the benzo[c]phenanthrene moiety over the plane of the complex.

The preparation of the ditertiary phosphines 2,11-bis (di-m-tolylphosphinomethyl)benzo [c]phenanthrene (1b), 2,11-bis (di-p-anisylphosphinomethyl)benzo-[c]phenanthrene (1c), 2,11-bis (di-m-trifluoromethylphenylphosphinomethyl) benzo-[c]phenanthrene (1d), 2,11-bis (dicyclohexylphosphinomethyl)benzo [c]phenanthrene (1e) and 2,11-bis [di-(t-butyl)phosphinomethyl]benzo [c]phenanthrene (1f), by a combination of synthetic routes is described.

Reactions of tantalum pentaethoxide with p-haloarylsubstituted β-diketones as well as 2-thenoyltrifluoroacetone were carried out using different molar ratios. Compounds of the type [Ta(OEt)5-n(L)n], (where L = p-fluoro-, p-chloro-, p-bromobenzoylacetone and 2-thenoyltrifluoroacetone; n = 1, 2 or 3), have been isolated and characterised by elemental analysis, molecular weight determinations and spectral studies like i.r., and 1H n.m.r. Alcoholysis reactions with tertiary butanol were also carried out.

New complexes of the type [M(CO) 4 (dptpe)] (M = Cr, Mo, W) have been isolated from the reaction of the ligand, 1, 2-bis(di- p -tolylphosphino)ethane (dptpe) with Group VI metal hexacarbonyls in a suitable solvent such as methylcyclohexane. The resulting [M(CO) 4 (dptpe)] complexes on treatment with an excess of pyridine produces the mixed ligand complexes [M(CO) 3 (py)(dptpe)], whereas the reaction of [XMo(CO) 2 (η 3 -allyl)(MeCN 2 )] (X = Cl, Br) with dptpe gives [XMo(CO) 2 (η 3 -allyl)(dptpe)]. The formulation of the structures of these complexes follows from elemental analyses and 1 H NMR, 31 P{ 1 H} NMR and IR spectral studies. Carbonyl force constants have been calculated from the ν(CO) stretching frequencies by the Cotton and Kraihanzel method.

A series of four-coordinate, square-planar, dia- magnetic 1-diphenylphosphino-2-bis(m-trifluoro- methylphenyl)phosphinoethane complexes of type cis-[MX2(m-CF3P-P)] (M = Ni, Pd, Pt; X = Cl, Br, I or NCS) have been prepared. These complexes have been characterized by 31P {1H} NMR, 1H NMR, IR and UV spectroscopy, elemental analyses and magnetic susceptibility measurements. The effects of various substituents on the phenyl groups of the ditertiary phosphines on the solubility characteristics of the metal complexes are discussed.

Compounds of the type [M(OPri]m-n(L)n] (where m=3 and n=1 to 3, M=La, Sm, Nd or Gd and L=C7H5O3 −, C9H7O2 − and C9H9O2 −) have been synthesised by the reactions of lanthanide isopropoxides with furylacrylic acid (C7H5O3), cinnamic acid (C9H8O2) and dihydro cinnamic acid (C9H10O2) in benzene. All compounds have been characterised by elemental analysis, and infrared spectral studies. On the basis of infrared studies it is suggested that all these acids behave as a bidentate chelate of the type

The bidentate diphosphine ligand, 3,3′-oxybis[(dipenylphosphino)methylbenzene] (1) forms monomeric, trans-square-planar complexes MX2(1) (M = Ni, Pd, Pt; X = Cl−, Br− I−, and, in part, N, NCS−, CN−, NO) as well as Pt(H)Cl(1), Pt(H)Br(1), and RhCl(CO)(1). Polymeric species have been observed with substitutionally inert metal centres: trans-[PtCl2(1)]2 and cis-[PtCl2(1)]n (mean value of n ≈ 4–5) 31P-NMR, and selected IR and UV/VIS parameters are reported. Ligand 1 shows a marked preference for trans-spanning and monomeric chelate formation, despite its various degrees of freedom of internal rotation in the lignad backbone. The readily available ligand 1 as well as analogues with other donor atoms, therefore, appear useful in most potential applications of trans-spanning chelate ligands. The crystal structure of AgCl(1)·0.5 (CH3)2CO·0.39 C6H12 (space group C2/c,a = 21.02 A, b = 14.57 A, c = 24.79 A, β = 99.77°, V = 7531.4 A3, Z = 8) confirms the presence of three-coordinate Ag(I), with a coordination intermediate between a trigonal-planar and a T-shaped geometry (P-Ag-P = 145.61(8)°).

Tetraalloxygermanium(IV), (CH 2 ·CH·CH 2 ·O) 4 Ge, has been synthesized from germanium tetrachloride, allyl alcohol, and ammonia. The alloxides [(CH 2 ·CH· CH 2 ·O) 4 Ti] 2 and[(CH 2 ·CH·CH 2 O) 5 M] 2 (M = Nb and Ta) have been synthesized by reactions of the corresponding metal isopropoxides with allyl alcohol followed by removal of the isopropanol by azeotropic distillation with benzene. These four metal alloxides can be purified by distillation under reduced pressure. The spectroscopic properties of these new compounds are discussed.

The reaction of PtCl2L (L = diphosphine) with the appropriate diphosphine L′ in ethanol followed by reduction with aqueous sodium borohydride leads to either disproportionation to give mixtures of the bis(diphosphine) complexes PtL2 and PtL′2 or to the formation of the mixed ligand complex PtLL′ depending on the diphosphines. Mixed ligand complexes are obtained when L=Ph2P(CH2)2PPh2, L′ = Ph2P(CH2PPh2 cis-Ph2PCH CHPPh2, Ph2P(CH2)2AsPh2, Ph2- P(CH2)4PPh2, o-Ph2PC6H4PPh2; and L=(C6H11)2P(CH22P(C6H11)2, L′= Ph2P(CH2)PPh2, Ph2P(CH2)2PPh2 cis-Ph2PCHCHPPh2, (2S,3S)-Ph2PCH- (CH3)CH(CH3)PPh2, (R)-Ph2PCH(CH3)CH2PPh2. When L=Ph2P(CH2)4PPh2 L′= Ph2P(CH23PPh2 or cis-Ph2PCHCHRPh2 the mixed ligand complexes are obtained but extensive disproportionation also occurs.

Complexes of the type [M(CO)4(PP′)] (M = Cr, Mo, W; PP′ = R2PCH2CH2PPh2, R = m-FC6H4(1a), R = p-FC6H4 (1b), R = m-CF3C6H4 (1c)) have been obtained from the reaction of appropriate metal hexacarbonyl with the corresponding ditertiary phosphine in methylcyclohexane/xylene. The order of ease of replacement of carbonyl by these phosphines was found in the sequence of Mo > Cr > W. The complexes [M(CO)4(PP′)] react with excess of pyridine to yield the trisubstituted complexes [M(CO)3(py)(PP′)] (M = Cr, Mo, W; py = pyridine; PP′ = 1a, 1b or 1c). All the complexes have been characterized by elemental analysis and IR and 1H NMR spectroscopy, and are assigned octahedral structures. Carbonyl force constants have been calculated from the (ν)(CO) stretching frequencies. 31P{1H}NMR spectra of [M(CO)4(PP′)] complexes reveal unusually large downfield shifts upon coordination, and these are explained in terms of a ring contribution. The values of the tungsten-phosphorus J(183W-31P) and phosphorusphosphorus J(31P31P′) coupling constants are discussed.

The new chelating ditertiary phosphine (pptpf) forms low spin, diamagnetic, square-planar complexes of the type [M(pptpf)X2] (where M=Ni(II), Pd(II) or Pt(II); X=Cl, Br, I or NCS) when treated with corresponding metal salts. Group VI metal hexacarbonyls also react with the ligand (pptpf) to yield diamagnetic, octahedral complexes of type [M(CO)4(pptpf)] (where M=Cr, Mo or W). These complexes have been characterised on the basis of their elemental analysis, 1H n.m.r., electronic, infrared spectral measurements, electrical conductance and magnetic susceptibilities data. In all the complexes the ligand (pptpf) acts as a chelating ditertiary phosphine.

The ditertiary phosphines; [2-{di(p-tolyl)phosphino}ethyl] diphenylphosphine (pptpf) and [2-{di(m-tolyl}ethyl] diphenylphosphine (pmtpf) complexes of ruthenium of the type: [Ru(pptpf)2X2] [Ru(pmtpf)2X2] (where X = Cl,Br, I or NCS), [Ru(CO)2X2(pptpf)] and [Ru(CO)2X2(pmtpf)] (where X = Cl, Br, or I) were prepared. trans-octahedral structure for [Ru(pptpf)2X2] and [Ru(pmtpf)2X2] complexes and cis-octahedral structure for [Ru(CO)2X2(pptpf)] and [Ru(CO)2X2(pmtpf)] complexes on the basis of IR and proton NMR data have been suggested. In all these complexes ligands (pptpf) and (pmtpf) act as chelating ditertiary phosphines.