Search results for "Adduct"
showing 10 items of 320 documents
Orthometallation reactions of tris(p-methoxyphenyl)phosphine with dirhodium(II) tetraacetate
1998
Abstract Reactions of dirhodium(II)tetraacetate [Rh2(OAc)4] with tris(p-methoxyphenyl)phosphine (PMP) at 1:1 and 1:2 molar ratios yield, first appropriate adducts: [Rh2(OAc)4P(p-CH3OC6H4)3] (1a) and [Rh2(OAc)4{P(p-CH3OC6H4)3}2] (2a), and then orthometallated [Rh2(OAc)3{μ-(p-CH3OC6H3)P(p-CH3OC6H4)2}(HOAc)2] (1) and [Rh2(OAc)2{μ-(p-CH3OC6H3)P(p-CH3OC6H4)2}2(HOAc)2] (2) complexes, respectively. They have been characterized by spectroscopic methods. The molecular structure of 1 has been determined by the X-ray methods. Crystal data: space group P1, a=11.085(5), b=11.387(5), c=13.900(6) A, α=97.29(3), β=105.23(3), γ=91.93(3)°. In this compound The Rh–Rh distance is 2.421(1), Rh–P bond length 2.1…
Synthesis of bis(diphenylphosphinocyclopentadienyl) yttrium chloride complexes and heterodimetallic derivatives. X-ray structure of bis[(μ-chloro)bis…
1996
Abstract Reaction of lithium diphenylphosphinocyclopentadienide with YCl 3 or YCl 3 (THF) 3 and working lead to the formation of three yttrocene phosphines: the lithium metal adduct isolated as (Ph 2 PC 5 H 4 ) 2 Y(μ-Cl) 2 Li(THF) 2 · 0.5 LiCl ( 1 ), the chloride-bridged dimeric species {(Ph 2 PC 5 H 4 ) 2 Y(μ-Cl)} 2 ( 2 ), and the coordinated monometal species [(Ph 2 PC 5 H 4 ) 2 YCl(THF)] ( 3 ). The X-ray structure of 2 is remarkable in that the crystal exhibits two independent chloride-bridged dimers that differ in the arrangement ( syn, anti ) of the diphenylphosphino groups. Chelation of phosphorus atoms to a molydenum carbonyl moiety is also reported.
A study of the atmospherically important reactions between dimethyl selenide (DMSe) and molecular halogens (X2 = Cl2, Br2, and I2) with ab initio cal…
2012
The atmospherically relevant reactions between dimethyl selenide (DMSe) and the molecular halogens (X(2) = Cl(2), Br(2), and I(2)) have been studied with ab initio calculations at the MP2/aug-cc-pVDZ level of theory. Geometry optimization calculations showed that the reactions proceed from the reagents to the products (CH(3)SeCH(2)X + HX) via three minima, a van der Waals adduct (DMSe:X(2)), a covalently bound intermediate (DMSeX(2)), and a product-like complex (CH(3)SeCH(2)X:HX). The computed potential energy surfaces are used to predict what molecular species are likely to be observed in spectroscopic experiments such as gas-phase photoelectron spectroscopy and infrared matrix isolation s…
Study of Pinna nobilis growth from inner record: How biased are posterior adductor muscle scars estimates?
2011
abstract Article history:Received 14 June 2011Received in revised form 19 July 2011Accepted 20 July 2011Available online 17 August 2011Keywords:BivalviaEndangered speciesMediterraneanSclerochronologySpain Previous studies have shown that the external growth records of the posterior adductor muscle scar (PAMS)ofthe bivalve Pinna nobilisareincomplete and donot produce accurate ageestimations. We havedeveloped anew methodology to study age and growth using the inner record of the PAMS, which avoids the necessity ofcostly in situ shell measurements or isotopic studies. Using the inner record we identified the positions ofPAMS previously obscured by nacre and estimated the number of missing recor…
Crystal structure of the borabenzene–2,6-lutidine adduct
2015
In the title compound, C12H14BN, the complete molecule is generated by a crystallographic twofold axis, with two C atoms, the B atom and the N atom lying on the rotation axis. The dihedral angle between the borabenzene and pyridine rings is 81.20 (6)°. As well as dative electron donation from the N atom to the B atom [B—N = 1.5659 (18) Å], the methyl substituents on the lutidine ring shield the B atom, which further stabilizes the molecule. In the crystal, weak aromatic π–π stacking between the pyridine rings [centroid–centroid separation = 3.6268 (9) Å] is observed, which generates [001] columns of molecules.
Intubationsbedingungen nach Rocuronium und Succinylcholin
1996
OBJECTIVE Rocuronium is a new non-depolarising steroidal muscle relaxant with a short onset time. The present study was undertaken to compare intubating conditions as well as onset and clinical duration of a single dose of 0.6 mg/kg (2 x ED95) with a single dose of 1 mg/kg suxamethonium (3 x ED95). METHODS After obtaining informed consent and approval of the Ethics Committee, 40 adult patients (ASA I-III) participated in this study. After premedication with oxazepam, anaesthesia was induced with fentanyl and propofol and maintained with propofol, N2O and supplements of fentanyl as needed. Muscular relaxation was assessed by EMG recording of adductor pollicis muscle after supramaximal single…
Preparation of dithiacycloalkynes by cyclization reactions applying the cesium effect
1993
Abstract The strained dithiacycloalkynes 3a,b and the larger heterocyclic alkynes 3c and 4 are obtained by cesium assisted cyclization reactions of the dithiols 1a–c and 1,4-dibromo-2-butyne (2). The reactivity of 3a–c was studied in cycloaddition and complexation reactions generating the adducts 5a,b and 6 and the silver and cobalt complexes 7 and 8.
Tin(IV) and organotin(IV) derivatives of bis(pyrazolyl)acetate: Synthesis, spectroscopic characterization and behaviour in solution.
2005
Abstract Novel heteroscorpionate-containing tin and organotin(IV) complexes, [SnRnX3 − n(L)], R = Me, Bun, Ph, or cy; X = Cl, Br or I, n = 0, 1, 2 or 3; L = bis(pyrazol-1-yl)acetate (bpza) or bis(3,5-dimethylpyrazol-1-yl)acetate (bdmpza), have been synthesized and characterized by spectral (IR, 1H, 13C and 119Sn NMR, 119mSn Mossbauer) and analytical data. In [SnI3(bdmpza)], the ligand is fac-N,N′,O-tridentate, the three iodine atoms thus also fac about the six-coordinate tin(IV) atom. Neutral bpzaH reacts with BunSnCl3, PhSnCl3 and SnCl4 in Et2O in the absence of base, yielding 1:1 adducts [XSnCl3(bpzaH)] (X = R or Cl).
Addition von Phosphor‐Nucleophilen an Benzothiet
1991
Addition Reactions of Phosphorus Nucleophiles to Benzothiete Trialkyl phosphites 4 add to the o-quinoid form 2 of benzothiete (1) to yield the phosphonates 6. An intermolecular migration of an alkyl group from oxygen to sulfur is the most important feature of this transformation. The rearrangement – related to the Arbuzov reaction – can be avoided in a two-step process by the subsequent action of PCl3 and alcohol; thus the phosphonates 10 are generated. Analogous to 2 6, dimethyl phenylphosphinate (11) furnishes 13. In contrast, the cyclic esters 14a–d form 2:1 adducts, namely the 12- to 15-membered heterocyclic compounds 17a – d. An intramolecular rearrangement in a 1:1 adduct is only obse…
ChemInform Abstract: Stereoselective Synthesis of syn-α-Methyl-β-hydroxy Esters.
2000
Abstract Boron enolates of an ethyl ketone structurally related to erythrulose react with achiral aldehydes in a highly stereoselective fashion to yield 1,2- syn /1,3- syn stereoisomers. Oxidative cleavage of the aldol adducts yields enantiopure O -formylated syn -α-methyl-β-hydroxy esters, easily cleaved to the corresponding hydroxyl-free compounds. The aforementioned ketone behaves therefore as a chiral propionate enolate equivalent.