bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heterobimetallic Complexes with a Propynylidene C3‐Bridge: General Synthetic Routes to Bimetallic Ethynylcarbene Complexes
Authors: Hartabum Cornelia , Roth Gerhard , Fischer Helmut 
Published: July 2007

AbstractSequential reaction of the dimethylamino(trimethylsilylethylnyl)carbene complexes [(CO)5M'C(NMe2)CCSiMe3] [M' = W (1a)] with KF/THFMeOH, nBuLi and transition metal halides, [XMLn], affords heterobimetallic propynyliden complexes of the type [(CO)5M'C(N‐Me2)CCMLn] [MLn = Ni(PPh3) Cp (4a, b). Ni(PMe2Ph)2‐ {Mes) (Mes=2,4,6‐C6H2Me3) (5a), Rh(CO)(PPh3)2 (6a), Fe(CO)2Cp (7a,b)]. In contrast, reaction of 1a with MeLi · LiBr and [IFe(CO)2Cp] yields the novel N‐metallated complex [(CO)5WC{N(ME)Fe(CO)2Cp}CCSiMe3] (8a). The complexes [(CO)5M'C(NMe2)CCMLnFe(CO)2Cp (7a, b), Ru(CO)2Cp (10a,b), Ru(CO)(PPh3)Cp (11a), Mn(CO)5 (12a), Re(CO)5 (13a)] are accessible by Pd‐catalyzed coupling of the C‐stannylated carbene complexes [(CO)5M'C‐(NMe2)CCSnBu3] (9a, b) with [XMLn]. The related monomethylaminocarbene complexes [(CO)5M'C(NHMe)C CSnBu3] (16a, b), obtained by stannylation of [(C))5M'C(NHMe)CCH] (15a, B) with Bu3SnNEt2, react with [IFe(CO)2Cp] to give the bimetallic complexes [(CO)5M'C(NHMe)CCFe(CO)2Cp] (17a, b). The complexes 4a, 5a, 7a and 10a were characterized by X‐ray structural analysis. The spectroscopic and structural data suggest that the two metal centers in 4–7, 10–13, and 17 interact only weakly.
N2Hx Coordination at the Tripod‐Cobalt Template CH3C(CH2PPh2)3Co: the Transformation of η2‐HNNMe2 into η1‐NNMe2Ligands
Authors: Körner Volkmar , Huttner Gottfried , Vogel Sabine , Barth Annette , Zsolnai Laszlo 
Published: July 2007

AbstractWhile η2‐coordination of N2H4 and N2H3‐ to tripod‐cobalt entities has been reported, stabilization of N2H2 in this system has not yet been achieved. It is observed that [tripodCo(η2‐HNNMe2)]+ (3) is transformed into [tripodCo(η1‐NNMe2)]+ (4) by reaction with LiN(TMS)2 as a base. The deprotonation of 3 is accompanied by a redox reaction, and the overall reaction corresponds to the transformation of 3 to 4 with the loss of an electron and a proton. The observed coupling of deprotonation and oxidation is just the reverse of the processes assumed to occur during nitrogen fixation. The results are established by the usual analytical and spectroscopic techniques as well as by X‐ray analyses.
Reactions of Complex Ligands, LXXIIIntermolecular Pauson‐Khand Reactions of Ethyl 2‐Phenylethynylcyclopropanecarboxylates and [Amino(trans‐2‐phenylethynylcyclopropyl)methylidene]pentacarbonylchromium(0)
Authors: Kretschik Oliver , Heinz Dötz Karl , Nieger Martin 
Published: July 2007

AbstractThe intermolecular Pauson‐Khand reactions of ethyl trans‐2‐phenylethynylcyclopropanecarboxylate (1t) and [amino‐(trans‐2‐phenylethynylcyclopropyt)methylidene]pentacarbonylchromium (9) with norbornane lead to ester and metal carbene functionalized exo‐tricyclodecenones 3b–6 and 13–16, respectively, in moderate to high yields. The incorporation of the alkyne is moderately regioselective but less diastereoselective. Pairs of diastereomers are isolated after column chromatography, which can subsequently be separated by recrystallization. The minor diastereomer 3 and the major diastereomer 15 are characterized by X‐ray structure analysis.
Highly Substituted Cyclams: Stereoselective Synthesis and Coordination Properties
Authors: König Burkhard , Pelka Mario , Möller Oliver , Dix Ina , Jones Peter G. 
Published: July 2007

AbstractWe report here a new synthetic route to highly‐substituted tetraazamacrocycles. Raney nickel hydrogenation of macrocyclic phenylenediamine–acetylacetone condensation products gives cyclams in high yield with complexes all‐cis stereoselectivity. The extensive C‐substitution of the cyclam 2a changes its ligand properties markedly. The X‐ray structure analyses of NiII, CuII, and ZnII complexes of 2a reveals a deviation of the metal ion coordination geometry from the usual square‐planar arrangement. This may account for the differences in the redox properties of the NiII and CuII complexes of 2a leads to more positive oxidation and reduction potentials compared to the analogous unsubstituted cyclam complexes. While the binding constant between Zn(ClO4)2 and 2a is lower by a factor of 105 compared to cyclam, the subsequent binding of uridine to the zinc‐cyclam complexes in methanol/water is slightly stronger in the case of 2a · Zn(ClO4)2].
Inter‐ and Intramolecular Thermal Activation of Aliphatic C–H Bonds Mediated by Complexes Containing the Fragments [{Cy2P(CH2)nPCy2}M] (n=1–4, M = Rh, Ru)
Authors: Leitner Walter , Six Christian 
Published: July 2007

AbstractA well defined geometrical structure and a well established catalytic potential for a plethora of processes puts the chelate rings [{R2P<(CH2)nPR2}M] (M = Rh, Ru) among the most interesting candidates for catalytic alkane functionalization in homogeneous solution. It is demonstrated that intermolecular thermal C–H activation (3→4) is possible with readily accessible complexes [{Cy2P(CH2)nPCy2}Rh(hfacac)] (n = 1–4, 1a–c and [Cy2P(CH2)nPCy2}Ru(η3‐C4H7)2] (n = 1–3, 2a–c) containing such fragments. A maximum of 5 catalytic cycles was achieved with complex 2a. In case of Ru complexes containing the same ligands with n =3 and 4, intramolecular cleavage of three adjacent C–H bonds in one of the cyclohexyl substituents at phosphorus also occurs readily leading to formation of a new polydentate k2P,P', η3‐allyl ligand.
Halfsandwich‐Type Triisopropylstibane Ruthenium Complexes with 16‐, 17‐, and 18‐Electron Configurations and an Unsymmetrical Binuclear 18/16‐Electron Ru2(SbiPr3) Species
Authors: Braun Thomas , Laubender Matthias , Gevert Olaf , Werner Helmut 
Published: July 2007

AbstractThe paramagnetic ruthenium complex [(η5‐C5Me5)RuCl2‐{SbiPr3}] (2), which is prepared from [(η5‐C5Me5)RuCl2]n (1) and SbiPr3, reacts with Mg/Hg in THF to give the coordinatively unsaturated 16‐electron species (η5‐C5Me5)RuCl)(SbiPr3)] (3). Compound 3 is obtained in much better yield from [(η5‐C5Me5)Ru(μ3‐Cl)]4 (4) and SbiPr3 (molar ration 1:4). While 3 reacts with CO to give the 18‐electron complex [(η5‐C5Me5)RuCl(CO)(SbiPr3)] (5), on treatment of 3 with HCˇO2Me the metallacycle [(η5‐C5Me5)RuCl{k2(C,C)‐C(CO2Me}=CHC(CO2Me)=CH}(SbiPr3)] (6) is obtained. The reaction of 4 with SbiPr3 in the molar ratio of 1:2 affords the binuclear compound [(η5‐C5Me5)(SbiPr3)Ru(μ‐Cl)2Ru(‐C5Me5)] (7). The molecular structures of 2 and 7 have been determined by X‐ray crystallography.
Iminoacylcobalt Compounds as Starting Materials for the Synthesis of Alkynylcobalt Halfsandwiches and Cobaltaheterocycles
Authors: Werner Helmut , Xiaolan Liu , Peters Karl , von Schnering Hans Georg 
Published: July 2007

AbstractThe iminoacylcobalt compound [C5H5Co(C(CH3)=NCH3)(PMe2Ph)] (3) reacts with propargylic acid ester HC=CCO2R (R = Me, Et) to give the alkynylcobalt halfsandwich‐type complexes [C5H5Co(C(CH3)=NHCH3)(C=CCO2R)‐(PMe2Ph)]I (5, 6). With HC=CCO2Me as the substrate, besides 6 (R = Me) the five‐membered cobaltaheterocycle [C5H5Co{K2(N, C)‐N(CH3)C(CH3)CHC(CO2Me)}(PMe2Ph)]I (7) is also obtained. The reactions of 3 and the analogous benzyl derivative 4 with terminal alkynes HC=CR' (R' = CH2OH, CMe2OH, [CH2]2OH, CH2OMe, H, Me, nBu, Ph) afford exclusively the heterocyclic complexes [C5H5Co(K2(N,C)‐N(R)C(CH3CHCR')(PMe2Ph)]I (R = CH3, CH2Ph) (8–18) in 60–70% yield. The molecular structures of 5 (R = Et) and 16 (R = Me, R' = Ph) have been determined by X‐ray crystallography.
C–H Bond Activation of Simple Alkenes with (C5H5)CO Fragments: Preparation, Molecular Structure, and Dynamical Behaviour of Tri‐ and Tetranuclear Cyclopentadienylcobalt Cluster complexes with μ‐Cycloalkyne Ligands
Authors: Wadepohl Hubert , Borchert Till , Pritzkow Hans 
Published: July 2007

AbstractVicinal C–H bonds of the cycloalkenes CnH2n (n = 5–8) were activated upon treatment under mild conditions with reactive sources of the (C5H5)CO fragment. With [C5H5)CO(C2H4)2] (2a), the trinuclear cluster complexes [H2((C5H5)CO)3(μ3‐C2(CH2)n‐2)] (5a: n = 5; 5c: n = 5d: n = 8) were formed. Using the more reactive [(C5H5)2Co]/K, 5a–5dwere obtained, along with small amounts of the tetranuclear [{(C5H5)CO}4r{μ4‐C2(CH2)n‐2}] (8a–c: n = 5–7). X‐ray structure analyses of 5c, d and 8b, c were performed. A μ‐‖ (orμ3‐η1:η2:η1) coordination of the cycloalkyne ligands was found in the trinuclear cluster complexes. The tetranuclear 8b, c had the cycloalkynes quadruply bridging (μ4‐η1:η2:η2:η1_ a butterfly arrangement of the metal atoms. The acetylenic carbon–carbon bonds are considerably lengthened upon coordination [1.392(4), 1.398(3) å in 5c d; 1.464(8), 1.499(5) Å in 8b, c]. Three dynamic processes – alkyne “walk” on top of the CO3 triangle, μ2‐hydride migration, and μ2/μ3‐hydride exchange – are operational in the trinuclear 5a–d. Dynamic NMR data for 5a are consistent with a “windshield‐wiper” mechanism for the alkyne migration. Hydride exchange is associated with a higher energy barrier, and is probably and independent dynamic process.
On the Protonation of Fluoro Cryptands and the Possibility of CF…HN+ Hydrogen Bonds
Authors: Plenio Herbert , Diodone Ralph 
Published: July 2007

AbstractThe protonation of several fluoro cryptands synthesized from 1,3‐bis(bromomethyl)−2‐fluorobenzene and diaza‐macrocycles (diaza‐12‐crown‐4, diaza‐15‐crown‐5, diaza‐18‐crown‐6 and 2,3‐benzodiaza‐15‐crown‐5) has been investigated by 1H‐, 13C‐ and 19F‐NMR spectroscopy, X‐ray crystal structure analysis and IR spectroscopy, with a view to detecting possible CF…HN hydrogen bonding. From the crystal structures of mono‐ and diprotonated 23‐fluoro‐4,7,20‐trioxa‐1,10‐diazatricyclo[8,7,5,112,16]tricosa‐12,14,16(23)‐triene (FN2O3·H+ and FN2O3·2H+) it is apparent that protonation leads to a shortening of the non‐bonded nitrogen‐fluorine and nitrogen‐oxygen distances and consequently to O·HN hydrogen bonds. A related type of interaction involving fluorine appears possible since short N(H)…F distances (281.2–286.6 pm) with NHF angles between 130–140° are observed. A Cambridge Structural Database search was performed and 27 structures with short CF…HN contacts were found. On the other hand, IR spectra do not give any clear evidence in favor of CF…HN hydrogen bonding since the N–H vibrations in FN2O3…H+ and FN2O3…2H+ as well as in FN2O4…2H+ do not experience longwave shifts relative to the N–H vibrations of the reference systems HN2O3·H+, HN2O3…2H+ and HN2O4…2H+.HN2O3 and HN2O4 are almost identical to FN2O3 and HN2O4, respectively, the only difference being that the single fluorine atom of the fluoro cryptands is replaced by hydrogen. NMR spectroscopic evidence concerning CF…HN interactions is ambiguous: (i) A spin‐coupling between 1H and 19F (NH…F) is observed. (ii) The 1JCF value is reduced by up to 15 Hz upon protonation of the fluoro cryptand. (iii) An NMR competition experiment between FN2O3 and HN2O3 yields no evidence for an increased basicity of the fluoro cryptand. Finally, it can be stated that evidence in favor of CF…HN hydrogen bonds is inconclusive; should such an interaction exist it will certainly be very weak.
Gold Coordination by 2‐(Diphenylphosphanyl)aniline
Authors: López‐De‐Luzuriaga José M. , Schier Annette , Schmidbaur Hubert 
Published: July 2007

AbstractThe reaction of 2‐(diphenylphosphanyl)aniline (1) with (tetrahydrothiophene)gold(I) chloride in the molar ratio 1:1 gives a stable molecular complex 2, in which the gold atom is bonded to the phosphorus atom. Reaction of two equivalents of ligand 1 with one equivalent of the salt [(tht)2Au]ClO4 results in the displacement of both thioether ligands, affording the ionic complex {[(2‐NH2C6H4)PPh2]2Au}+ ClO−4 (3a), in which the metal center is exclusively P‐coordinated. Treatment of [(tht)2Au]ClO4 with ligand 1 (1:1) affords the mixed P/S‐coordinated complex 4, the structure of which has been confirmed by single‐crystal X‐ray diffraction. The reaction of ligand 1 with [(Ph3P)Au]+ BF−4 leads to a mixture of products which are components of an equilibrium between the unsymmetrical salt {[(2‐NH2C6H4)PPh2]Au(PPh3)} BF−4 with the two symmetrical species 3b (the BF−4 analogue of 3a) and [(Ph3P)2Au]+ BF−4, With {[(Ph3P)Au]3O}+ BF−4 as the aurating agent, the ligand 1 (molar ratio 1:1) is converted into a polynuclear complex 7, which is tentatively assigned a structure with intimate aggregation of six gold atoms.
Diastereoselective Synthesis of Tricarbonyl(thiophene)chromium Complexes
Authors: Ganter Christian , Brassat Lutz , Ganter Beate 
Published: July 2007

Abstract2,3‐Disubstituted 2‐hydroxyalkylthiophenes 9 and 10 were synthesized in a five‐step sequence and their diastereoselective complexation with the Cr(CO)3 fragment leading to the corresponding tricarbonyl(thiophene)chromium complexes 11 and 12 was investigated. The diastereoselectivity achieved in the complexation reaction was up to 85% d. e. and depends primarily on the bulkiness of the substituent in the 3‐position of the thiophene. The relative configuration of the stereogenic center and the planar element of chirality of complex 11a was determined by X‐ray diffraction analysis.
Monomeric Phosphanylgalanes — Synthesis and Structural Characterization
Authors: Linti Gerad , Köstler Wolfgand , Frey Ronald , Schwenk Holger 
Published: July 2007

AbstractThe monomeric phosphanylgallanes R2GaPR'R (R = tmp, Mes; R' = H, tBu; R' Mes, tBu), the diphosphanylgallane mesGa(PtBu2)2, and diphosphandiylbisgallane [tmp2GaP‐(tBu)]2, have been synthesized from alkali metal phosphides and substituted gallium chlorides. Low‐temperature NMR studies of the phosphanylgallanes reveal no barrier to rotation about the gallium‐phosphorus bond. Analysis of the crystal structures of tmp2GaPtBu2 confirms the monomeric nature of these molecules. The gallium‐phosphorus bond lengths are found to be 237.5, 233.5, 235.4 pm (averaged), and 242.3 pm, respectively, with all phosphorus atoms being pyramidally coordinated.
Divalent Tin and Lead Compounds EX2 Acting as Bridging Ligands in [{(CO)5M}2EX2]2− (E  Sn, Pb; M  Cr, Mo, W): Preparation and Properties
Authors: Kircher Peter , Huttner Gottfried , Schiemenz Berthold , Heinze Katja , Zsolnai Laszlo , Walter Olaf , Jacobi Albrecht , Driess Alexander 
Published: July 2007

AbstractThe reaction of Na2[M2(CO) 10] (M = Cr, Mo, W) with SnHal2 (Hal = Cl, Br) is a well established procedure for the synthesis of anions of type A, [{(CO)5M)SnHal3]−. Conditions are described which, for the same type of procedure, result in the additional formation of dianions of type B, [{(CO)5M}2SnHal2]2−. Procedures for separating these two types of anions in the form of their stable [Ph4P]+ or [nBu4N]+ salts by appropriate salt metathesis are presented. The structures of theses species have been characterized by X‐ray analysis of three salts containing type A anions and two salts containing type B anions. The reactivity of the type B salts containing the bulky cations [Ph4P]+ or [nBu4N]+, respectively, is remarkably low; the salts are, however, transformed into highly reactive sodium salts by further metathesis with Na[BPh4]. In such salts the halide substitutents are easily exchanged as shown by the synthesis of ]})CO(5Cr}2oxinato]− (4)− from [Na‐(THF)x]2[{(CO)5Cr}2SnCl2] and sodium 8‐oxoquinolate, Na[C9H6NO]. The structure of the anion, 4 is compared to the structure of [[(CO)5Cr)SnCl2· THF] and sodium 8‐oxochinolate. The preparation of the dinuclear anions [{(CO)5Cr}2E(OOCCH3)2]2− (E  Sn, 2g; E  Pb, 3) is accomplished by the reaction of [Ph4P]2[Cr2(CO)10] with the corresponding acetates E(OOCCH3)2. While 2g and 3 are formal analogues of the type‐B anions, their structures reveal an asymmetrical η2‐coordination of the two acetato ligands, in each case ending up in a 4+2 coordination for the main group centres, instead of the four‐coordination observed for [{(CO)5M}2SnHal2]2−, All compounds have been characterized by usual spetroscopic and analytical techniques. X‐ray analyses have been performed for selected examples. 119Sn‐NMR data are presented for all of the compounds which contain tin‐centred ligands.
Thermal Reactions of 5‐Alkylidene‐4,5‐dihydro‐3H‐1,2,4(λ3)‐diazaphospholes (4‐Phosphapyrazolines) – A Route to Various PHeterocycles and to 2‐Phosphabutadienes
Authors: Manz Berthold , Bergsträßer Uwe , Kerth Jochen , Maas Gerhard 
Published: July 2007

AbstractThe 5‐alkylidene‐4,5‐dihydro‐3H‐1,2,4(λ3)‐diazaphospholes (4‐phosphapyrazolines) are thermally much more stable than related compounds without the exocyclic double bond. Thermolysis reactions typically occur in the range 110‐150°C in toluene solution, and different, mostly competing, reaction pathways are observed. Thermal extrusion of nitrogen from 8a‐g gives rise to β‐phosphanaylsiloxyalkenes 10, benzo[c]‐phosphole derivatives 11, 14 and 115, (β‐siloxyalkylidene)‐Phosphiranes 12, and dihydro‐1,3‐oxaphospholes 13. The thermolysis of 5‐alkylidene‐4,5‐dihydro‐4‐trimethylsilyl‐3‐trimethylsilyloxy‐3H‐1,2,4‐dizaphospholes 17 afforded three products, including the highly substituted and stable 2‐phosphabutadienes 18 formed by nitrogen extrusion and rearrangement. Finally, the 4‐chloro‐3‐trimethylsilyloxy‐substituted heterocycle 21 was transformed at 170°C into 4H‐1,2,4‐diazaphosphole 23. The structures of 13c and 18a were determined by single‐crystal X‐ray diffraction.
Synthesis and Molecular Structure of a Rhenium Complex Derived from 8a‐Amino‐6‐methyl‐ergoline
Authors: Spies Hartmut , Noll Bernhard , Noll Steffi , Johannsen Bernd , Findeisen Matthias , Leibnitz Peter , Schulze Paul E. 
Published: July 2007

AbstractCurrent research in radiopharmaceutical chemistry is aimed at the design of technetium‐based receptor‐binding radiotracers because of the excellent nuclide properties of the isotope 99mTc. Tc tracers and the corresponding complexes of rhenium, as the inactive surrogate of Tc, are required to imitate organic agonists or antagonists of the receptor. We have started studies with ergolines, which are known to be dopamine substitutes. The present report deals with the functionalization of 8α‐amino‐6‐methyl‐ergoline (2) with a 2‐mercaptoacetyl group, and the subsequent synthesis of the first rhenium complex containing a pendent ergoline moiety [Re‐ O(SSS)(RS)] (HSSSH = HS‐CH2CH2‐S‐CH2CH2‐SH and RSH = 8a‐amino‐N‐(2‐mercaptoacetyl)‐6‐methyl‐ergoline) (4). The molecular structure of the rhenium complex was determined by X‐ray crystal structure analysis.
The Chemistry of Metallacyclic Alkenylcarbene Complexes, 8 Chelated Allyl‐Ironcarbene Complexes with a Centrally Tethered π‐Ligand‐Synthesis and Reactions with Nucleophiles
Authors: Förtsch Walter , Hampel Frank , Schobert Rainer 
Published: July 2007

AbstractThe title complexes 8 and 9 are easily prepared in two or three steps from iron carbonyls and isobutene diol 5 by Meerwein alkylation of the intermediate acyl complexes 6 and 7. With carbon and heteroatom nucleophiles like enolates and triphenylphosphane they form either stable 4‐substituted alkene‐carbene complexes 10 and 11, or substituted trimethylenemethane tricarbonyliron complexes like 12. Oxidation with H2O2/NaOH both of the alkene‐carbene complexes 11 and of the less stable β‐oxo‐substituted trimethylene‐methane complexes 13, as obtained from reaction of 8 with lithium enolates, yields the corresponding substituted allyl carbamates 15 or the allyl alcohols 14, which are formally bis‐ and monosubstituted derivatives, respectively, of the starting isobutene diol.
Nickel(II) Complexes of Chiral Tripodal N,O,S‐Ligands: Square‐Planar vs. pseudo‐Octahedral Coordination in the Solid State and in Solution, Metal‐Induced Racemization of the Ligand
Authors: Berkessel Albrecht , Seidel Lutz , Bats Jan W. , Bolte Michael , Neumann Thomas 
Published: July 2007

AbstractThe complexation behavior of three chiral, tripodal N,O,S‐ligands with nickel(II) salts was examined. It was found that the coordination mode of the ligands (bidentate N,O and N,S; tridentate N,O,S) and of the central nickel ion (square‐planar vs. pseudo‐octahedral) is not simply an intrinsic property of the ligand‐metal combination, but also a function of the counter ions and of the solvent of crystallization. In the case of one ligand, a diamagnetic square‐planar and a paramagnetic pseudo‐octahedral form could be switched back and forth, by just changing the solvent of crystallization from methanol to ethanol. By using an enantiomerically pure tripodal N,O,S‐ligand, a metal induced racemization was unveiled which would have otherwise remained undetected.
Organoantimony Oxides: Preparation and Crystal Structures of [(2‐PhOC6H4)O (C6H4)2Sb]2O2 and (o‐Tol2Sb)4O6
Authors: Breunig Hans Joachim , Probst Joachim , Ebert Klaus Heinz , Lork Enno , Cea‐Okuvares Raymundo , Alvarado‐Rodriguez José‐Guadalupe 
Published: July 2007

AbstractAir oxidation of (Oxydi‐2,1‐phenylene)(2‐phenoxyphenyl)stibane (1) gives the phenoxystibane oxide [(2‐PhOC6H4)O(C6H4)2Sb]2O2 (2). Single crystals of (o‐Tol2Sb)4− O4(O2)2 (3) were obtained by air oxidation of o‐TolSb‐(SiMe3)2. Crystal structures of 2 and 3 are reported.
The Coordination Chemistry of Fluorocarbons: Group‐I and Group‐ II Metal Ion Complexes of Fluoro Macrocycles
Authors: Plenio Herbert , Diodone Ralph 
Published: July 2007

AbstractTwo new fluoro macrocycles BenzoFN2O3 and F(N2O2)2C2H4 were synthesized in the reactions of 1,3‐bis(bromomethyl)‐2‐fluorobenzene with benzo‐diaza‐15‐crown‐5 and 1,2‐bis(diaza‐12‐crown‐4)ethane, respectively, in 30% yield each. Close CF...metal ion interactions in the respective alkaline metal complexes in solution are evidenced by characteristic shifts of the 19F‐NMR resonances of up to δ = 18.7 relative to the free ligand and by a decrease of the 1J(CF) coupling constant of up to 20 Hz, which is most pronounced in BenzoFN2O3 · Li+ and F(N2O2)2C2H4 · K+. In BenzoFN2O3· Li+ a1J(19F‐7Li) of 15.5 Hz was observed, which is indicative very close CF...Li+ interactions in solution. In the X‐ray crystal structures of BenzoFN2O3 · Na+ [CF ⃛Na+ 246.8(2) pm], 26‐fluoro‐4,7,13,16‐tetraoxa‐1, 10‐diazatricyclo[ 8.8.7.1 20,24 ] ‐ hexacosa‐20,22,24(26)triene · Na+ (CF ⃛Na+ 267.1(2) pm) and 21 ‐fluoro‐3,6,9,12,15,18‐hexaoxabicyclo[ 18.3.1 1,20]heneicosa‐ l(24),20,22‐triene. Ba2+ [CF ⃛Ba2+ 299.0(3) pm] short CF ⃛metal interactions were found. Such close CF ⃛metal ion interactions do not result in a lengthening of the C‐F bonds, which is not a sign of weak CF ⃛metal ion interactions, since a Cambridge Structural Database search revealed that a shortening of the C‐O bond length is also not observed in crown ether complexes of alkaline metals.
Donor Complexes of Silylene, Germylene, and Stannylene
Authors: Schoeller Wolfgang W. , Schneider Ralf 
Published: July 2007

AbstractThe complexes of various donor molecules, AH3 (A = N, P, As, Sb, Bi) and AH2 (A = 0, S, Se, Te) with silylene, germylene, and stannylene (1Al ground state) were studied by means of quantum chemical investigations at ab initio level utilizing all valence electron basis sets and relativistic corrected effective core potential methods. Accordingly, the donor molecules are weakly bound, the association energies are in the range of 15–30 kcal per mole. The exothermic energies for adduct formation, i.e., the resulting binding energies for the donor complexes, decrease in the order silylene > germylene > stannylene. The population analysis indicates for NH3 and BiH3 only a weak bonding towards the XH2 fragment (X =Si, Ge, Sn) while the higher homologues (A = P, As, Sb) form ylide structures, 1.2‐dipolaric in nature. The addition of two donor molecules has been studied for silylene and is much less favourable than donor mono‐addition. For the donor mono‐addition a dual parameter relationship between (a) the HOMO energies of the donor (n‐orbital of the AH3 unit, n, p‐orbitals for AH2) and (b) the covalent bond energies (from the literature) versus the binding energies of the donor‐acceptor compounds was examined. This dual parameter equation describes satisfactorily the essential features of the stabilities of the donor‐acceptor structures.