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Anionic 1,4-dihydro-1,4-diphosphinines were synthesized from tricyclic 1,4-diphosphinines and isolated as blue powdery salts M[

Three azadiphosphiridine complexes were selectively synthesized, two of them revealing a W(CO)5 group P-to-P′ haptotropic shift and only one displayed a planar ring N atom. Theoretical studies on ring formation and geometry as well as on the P-to-P′ haptotropic shift are reported.

A nanocrystalline TiO2 dye-sensitized solar cell device consisting of dye 2 and fabricated with commercially available materials reaches a conversion efficiency of η = 1.20%. Dye 2 is a low-cost and easily prepared copper(i) molecular sensitizer.

A μ2-(η1,η2)-dinuclear diphosphene complex having two W(CO)5 groups with dimethyl acetylenedicarboxylate, 4-phenyl-1,2,4-triazoline-3,5-dione and diethyl azodicarboxylate was applied to P-heterocyclic synthesis, i.e., using a singlet carbene-type reactivity of a homonuclear π-system assisted by a haptotropic shift thus rendering a more nucleophilic β phosphorus and, hence, a subsequent ring expansion.

Mixed-valence compounds feature the same atoms but in different formal oxidation states. This research field is largely dominated by metal-based solid-state chemistry and has been intensively studied in recent years. By contrast, the situation is different for molecular main group element compounds and to establish 1,1'-bifunctional groups remained a particular challenge. Here a detailed study on 1,1'-bifunctional mixed-valence main group compounds possessing a P-P bond is presented, and the fundamental role of the metal complex fragments is discussed. Based on the generation of a transient phosphanylidene-phosphinidenoid complex a dinuclear diphosphene complex was obtained possessing an unprecedented ambident reactivity, i.e., 1,2-addition or 1,1-addition products were obtained depending on the nature of the reagent. The 1,1-addition products represent stable hitherto unknown 1,1'-bifunctional phosphanylidene-phosphorane complexes which have been confirmed by X-ray diffraction studies. Detailed state-of-the-art DFT calculations provide insight into bonding and reaction pathways.

Diels-Alder-reactions of a thiazol-2-thione-based, tricyclic 1,4-di-phosphinine were investigated, showing that the central aromatic π-system can react with various dienophiles. The reaction with 4-phenyl-1,2,4-triazoline-3,5-dione was special as the product revealed a remarkable sensitivity towards light, thus enabling the photochemical deprotection of the tricyclic 1,4-diphosphinine.

P-OTEMP 1,3,2-heterophospholane tungsten complexes with different thermal stabilities were used to generate transient phosphanoxyl complexes which allow for a first-time radical polymerisation of acrylonitrile based on this methodology.

Synthesis of the tricyclic 1,3-dithiole-2-thione-derived 1,4-dihydro-1,4-diphosphinine is presented using a base-induced ring formation protocol and chloro(diethylamino)(1,3-dithiole-2-thion-4-yl)phosphane as the starting point. P-oxidation reactions of dihydrodiphosphinine by chalcogens led to bis(P-oxide), bis(P-sulfide), or bis(P-selenide), respectively; all tricyclic compounds were obtained as cis/trans mixtures. 1,4-Dihydro-1,4-diphosphinine was converted into 1,4-dichloro-1,4-dihydro-1,4-diphosphinine. This compound is almost insoluble in organic solvents, furnished selectively the trans-bis(amino) derivative upon a 2-fold P-substitution reaction with the weak nucleophile potassium bis(trimethylsilyl)amide, and reacted also with alcohols ROH (R = nBu, iPr, tBu) to give cis/trans mixtures of the corresponding bis(alkoxy) derivatives. Furthermore, the dichloro derivative could be reduced to a 1,4-diphosphinine using PnBu3, but, unfortunately, the stubbornly insoluble product could be neither purified nor crystallized. Despite this, we achieved a thermal [4 + 2] cycloaddition reaction of this first CPS-ternary compound with diethylacetylene dicarboxylate to obtain the corresponding diphosphabarrelene, thus providing indirect evidence for the aromatic tricyclic diphosphinine. Detailed density functional theory studies on the formation of 1,4-diphosphinine provided insights into formation pathways as well as NMR, IR, and UV/vis data.

The synthesis, isolation and structural characterization of the novel heteroleptic copper(I) complexes [Cu(RDABdipp)(LCOOMe)](PF6) (R = H (3), R = Me (4)) incorporating the sterically demanding 1,4-diaza-1,3-butadienes RDABdipp (R = H, Me; dipp = 2,6-diisopropylphenyl) is reported. 3 and 4 were isolated in high yields and spectroscopically characterized. The synthetic strategy includes the in situ reaction of the bis-acetonitrile intermediates [Cu(RDABdipp)(NCMe)2](PF6), (R = H (1), R = Me (2)) with the required amounts of the methyl-2-(pyridin-2-yl)-quinoline-4-carboxylate (LCOOMe) that was used as the ancillary ligand. 3 and 4 are rare examples of heteroleptic copper(I) complexes comprising RDABdipp and an ancillary α-diimine ligand, while 3 is the first crystallographically characterized example of this class of compounds. As a side product during the formation of 3 and 4, the homoleptic complex [Cu(LCOOMe)2](PF6) (5) is detected, that has been independently synthesized, for comparison. All the products were characterized by elemental analysis, FT–IR, UV–Vis and NMR spectroscopy. The molecular structures of 2·CH2Cl2, 3 and 5·CHCl3 were elucidated by single-crystal X-ray diffraction.

N,N-Diphenylamino- and N,N-dicyclohexylamino-substituted dichlorophosphane W(CO)5 complexes 1a,b were used to generate thermally very labile Li/Cl phospinidenoid W(CO)5 complexes 2a,b. The formation of transient complex 2a was confirmed via low-temperature 31P{1H} NMR spectroscopy, but further strong evidence for the formation of transient complexes 2a,b was obtained from reactions with methanol and methylamine as formal E–H insertions (E = O, N) furnished complexes 3a,b and 4a. By using toluene in the absence of donor ligands, the primarily nucleophilic complexes 2a,b were converted into electrophilic terminal phosphinidene complexes 5a,b which was deduced from specific trapping reactions using tolane, 1-pentene and 1-hexene and thus obtained 1H-phosphirene 6 and phosphirane complexes 7 and8. The state-of-the-art DFT calculations reveal insights into the possible reaction pathways and exclude a direct reaction of 2a,b with alkene trapping reagents.

A phosphanido-type bridged bis(imidazolium) salt, readily prepared in two steps via reductive deselenization of a tricyclic 1,4-diphosphinine diselone, affords access to a novel anionic P-functional tricyclic bis(NHC) via deprotonation. The former also offers a P-functionalization/deprotonation sequence to access the first mixed P-substituted tricyclic bis(NHCs), as well as coordination of the phosphorus centers to rhodium(I) fragments.

A rational approach to phosphaquinomethane metal(0) complexes, based on dearomatization of the phenylene unit in [W(CO)5](R)P(Cl)-C6H5-CPh2, is described, including theoretical studies on mechanisms and structures. Furthermore, the first phosphaquinone tungsten complex with reversible redox properties is reported thus illustrating the beneficial stabilization of ligation.

In this study we describe the one-pot and high yield synthesis of the ruthenium(II) complex cis-dichloride [RuCl2(PPh3)2(L1)] (L1 = 4-methyl-2-(2′-pyridyl)quinoline) (1). The solid state structure of L1 is described. The catalytic activity of 1 in the transfer hydrogenation of various ketones by 2-propanol at 82 °C, has been studied and compared with the activity of the known catalyst precursors cis-[RuCl2(PPh3)2(L2)] (L2 = 2-(2'-pyridyl)quinoline) (2), cis-[RuCl2(PPh3)2(L3)] (L3 = 2-(2′-pyridyl)quinoxaline) (3) and cis-[RuCl2(PPh3)2(bipy)] (bipy = 2,2′-bipyridine) (4). The ruthenium monohydride complex [RuHCl(PPh3)2(L3)] 3-H (Cl cis to H) was prepared from the reaction of 3 with 2.5 equivalents of a KOiPr solution. Reaction of 3 with 10 equivalents of KOiPr yields the cis-[RuH2(PPh3)2(L3)] (3-H2). Treatment of 1, 2 and 4 with KOiPr (in excess) affords the ruthenium cis-dihydride complexes [RuH2(PPh3)2(L1)] (1-H2), [RuH2(PPh3)2(L2)] (2-H2) and [RuH2(PPh3)2(bipy)] (4-H2). The formation of 1-H2, 2-H2, 3-H2 and 4-H2 is supported by NMR spectroscopic data. The cis-dihydrides 1-H2 to 4-H2 catalyze successfully the transfer hydrogenation of benzophenone to benzhydrol in the absence of a base, suggesting that presumably the active catalyst is a ruthenium dihydride complex (RuH2). Catalyst 1 has been potentially recovered and reused at least four times.

Formation of thermally unstable complexes [Mn(CO)2CpMe(R2PO-TEMP)] (Cp = cyclopentadienyl; Me = methyl; TEMP = 2,2,6,6-tetramethyl-piperidin-1-oxyl) is presented in this experimental and theoretical study; in case of R = Cy 31P NMR spectroscopic evidence is provided. Mechanistic details of the product formation and decomposition, due to a homolytic O–N bond cleavage, are revealed by high-level density functional theory calculations. Insights into stability and spin density distribution of transient phosphanoxyl complexes [Mn(CO)2CpMe(R2PO·)] and preliminary results on the acidity of related complexes [Mn(CO)2CpMe(R2P–OH)] and [W(CO)5(R2P–OH)] toward TEMP–H are presented.

Facile stereo- and regioselective ring opening of the oxaphosphirane complex A is presented using small molecules with differently polar E–H bonds (HCl, H2O, and NH3). The synthetic potential of the thus obtained novel 1,2-bifunctional ligands B is illustrated in cyclocondensation reactions, leading to the novel heterocyclic P-ligands C.

Metallosupramolecular systems heavily rely on the correct choice of ligands to obtain materials with desired properties. Engaging this problem, we present three ligand systems and six of their mono- and dinuclear complexes, based on the subcomponent self-assembly approach using electron-deficient pyridylcarbaldehyde building blocks. The properties are examined in solution by NMR and UV-vis spectroscopy and CV measurements as well as in solid state by single crystal X-ray diffraction analysis. Ultimately, the choice of ligands allows for fine-tuning of the electronic properties of the metal centers, complex-to-complex transformations, as well as establishing distinct anion-π-interaction motifs.

A novel method to prepare SiCp*2 (1) (Cp* = C5Me5) is presented involving the reaction of N-heterocyclic carbene (NHC)-stabilized SiII halides SiX2(NHC) (X = Cl, Br) with 2 equiv of KCp*. This route is a superior alternative to the laborious, multistep synthesis of 1 presently known and provides via the selective protonolysis of 1 with [H(Et2O)2][B(C6F5)4] facile access to [Si(η5-Cp*)][B(C6F5)4] (2) in multigram scale and high yield. Reaction of 2 with the tailored metallate Na[TpMeMo(CO)2(PMe3)] afforded the unprecedented silylidyne complex [TpMe(CO)2MoSi(η3-Cp*)] (3; TpMe = κ3-N,N′,N″-hydridotris(3,5-dimethyl-1-pyrazolyl)borate). Single crystal X-ray diffraction and spectroscopic studies in combination with quantum chemical calculations shed light on the unique bonding situation of 3 featuring a delocalized Mo–Si bond with partial triple bond character and a Cp* substituent, which is η3-coordinated to silicon.

Selective P–O bond activation of 1,2-oxaphosphetane complexes [(OC)5W(P{CH(SiMe3)2}CH2CRR′O)] (R/R′ = H/H (1a), H/CH3 (1b), H/CF3 (1c), CF3/CF3 (1d)) was achieved using different Bronsted acids. In case of acids with nucleophilic anions, such as HCl and HBF4·OEt2, the corresponding halophosphane complexes [(OC)5W(XP{CH(SiMe3)2}CH2CRR′OH] (X = Cl (2a–c), F (3c,d)) resulted as ring-opened products; 2b could be closed again with tBuLi/12-crown-4. In contrast, trifluoromethanesulfonic acid could be used to initiate either a ring-opening hydrolysis with a subsequent cleavage of the P–M bond to yield PH(O){CH(SiMe3)2}{CH2C(CF3)2OH} (7) or, in the presence of nitriles, a ring expansion yielding [(OC)5W(P{CH(SiMe3)2}CH2CH2OCR═N)] (R = CH3 (5a), Ph (5b), C(CH3)3 (5c)). P–O bond cleavage in 1a was achieved using the Lewis acidic catechol(chloro)borane to give [(OC)5W(P{CH(SiMe3)2}CH2CH(CH3)OBcat}Cl)] (8; cat = catechol).

Investigations on the reactivity of the transiently formed phosphanoxyl complex [(CO)5W(Ph2PO•)], thermally generated from [(CO)5W(Ph2PO-TEMP)] in toluene, is presented. Apart from self-reactions, trapping of this radical complex was achieved using group 14 hydrides Ph3EH (E = Si, Ge, Sn), leading to new phosphane complexes possessing a P–O–EPh3 bonding motif and the corresponding TEMP-H as byproduct. Reaction pathways, derived from DFT calculations, clearly revealed the intermediacy of various open-shell complexes; EPR measurements showed the presence of radicals, but unfortunately interpretation was not achieved.

The synthesis and full characterization of the NHC-stabilized tungstenochlorostannylene [Cp*(CO)3W–SnCl(Idipp)] (1Sn), the NHC-stabilized chlorogermylidyne complex [Cp*(CO)2W═GeCl(Idipp)] (2), the tungsten germylidyne complex salt [Cp*(CO)2W≡Ge(Idipp)][B(C6H3-3,5-(CF3)2)4] (3), and the cationic metallostannylene [Cp*(CO)3W–Sn(Idipp)][Al(OC(CF3)3)4] (4Sn) are reported (Idipp = 2,3-dihydro-1,3-bis(2,6-diisopropylphenyl)-1H-imidazol-2-ylidene, Cp* = η5-C5Me5). Metathetical exchange of SnCl2(Idipp) with Li[Cp*W(CO)3] afforded selectively 1Sn. Photolytic decarbonylation of the Ge analogue [Cp*(CO)3W–GeCl(Idipp)] (1Ge) afforded the NHC-stabilized chlorogermylidyne complex (2), featuring a trigonal-planar coordinated germanium center and a W–Ge double bond (W–Ge 2.3496(5) A). Chloride abstraction from 2 with Na[B(C6H3-3,5-(CF3)2)4] yielded the germylidyne complex salt 3, which contains an almost linear W–Ge–C1 linkage (angle at Ge = 168.7(1)°) and a W–Ge triple bond (2.2813(4) A). Chloride elimination from 1Ge a...

Syntheses of 1,1′-bifunctional aminophosphane complexes 3–10 was achieved by reacting Li/Cl phosphinidenoid complex 2 (R = CPh3) with secondary (Me2NH, Et2NH, Bn2NH, pyrrolidine, and piperidine), primary amines (EtNH2 and allyl amine), and ammonia. Furthermore, regioselective N-silylation of 11 (R = Me) was achieved using MeLi and Me3SiCl to give complex 12. In contrast, treatment of complex 6 with KHMDS in the presence of 18-crown-6 yielded K/NMe2 phosphinidenoid complex 13 subsequently reacted with MeI to give P–Me substituted 14. Complex 5 was deprotonated with KHMDS in the presence of 18-crown-6 and reacted with [Ph3C]BF4 to yield complex 17 via single-electron transfer reaction and P,C-heterocoupling. Finally, selective P–N bond cleavage was achieved by treating complex 18 (R = t-Bu) with HCl(g) to afford chlorophosphane complex 19.

A systematic, efficient approach to first complexes containing a triple bond between niobium and the elements silicon, germanium or tin is reported. The approach involves a metathetical exchange of the niobium-centered nucleophile (NMe4)[Nb(CO)4(κ2-tmps)] (1) (tmps = MeSi(CH2PMe2)3) with a suitable organotetrel(II)halide. Compound 1 was obtained from (NMe4)[Nb(CO)6] and the triphosphane tmps by photodecarbonylation. Reaction of 1 with the disilene E-Tbb(Br)SiSi(Br)Tbb in the presence of 4-dimethylaminopyridine afforded selectively the red-brown silylidyne complex [(κ3-tmps)(CO)2NbSi–Tbb] (2-Si, Tbb = 4-tert-butyl-2,6-bis(bis(trimethylsilyl)methyl)phenyl). Similarly, treatment of 1 with E(ArMes)Cl (E = Ge, Sn; ArMes = 2,6-mesitylphenyl) afforded after elimination of (NMe4)Cl and two CO ligands the deep magenta colored germylidyne complex [(κ3-tmps)(CO)2NbGe–ArMes] (3-Ge), and the deep violet, light-sensitive stannylidyne complex [(κ3-tmps)(CO)2NbSn–ArMes] (3-Sn), respectively. Formation of 3-Sn proceeds via the niobiastannylene [(κ3-tmps)(CO)3Nb–SnArMes] (4-Sn), which was detected by IR and NMR spectroscopy. The niobium tetrylidyne complexes 2-Si, 3-Ge and 3-Sn were fully characterized and their solid-state structures determined by single-crystal X-ray diffraction studies. All complexes feature an almost linear tetrel coordination and the shortest Nb–E bond lengths (d(Nb–Si) = 232.7(2) pm; d(Nb–Ge) = 235.79(4) pm; d(Nb–Sn) = 253.3(1) pm) reported to date. Reaction of 3-Ge with a large excess of H2O afforded upon cleavage of the Nb–Ge triple bond the hydridogermanediol Ge(ArMes)H(OH)2. Photodecarbonylation of [CpNb(CO)4] (Cp = η5-C5H5) in the presence of Ge(ArMes)Cl afforded the red-orange chlorogermylidene complex [Cp(CO)3NbGe(ArMes)Cl] (5-Ge). The molecular structure of 5-Ge features an upright conformation of the germylidene ligand, a trigonal–planar coordinated Ge atom, and a Nb–Ge double bond length of 251.78(6) pm, which lies in-between the Nb–Ge triple bond length of 3-Ge (235.79(4) pm) and a Nb–Ge single bond length (267.3 pm). Cyclic voltammetric studies of 2-Si, 3-Ge, and 3-Sn reveal several electron-transfer steps. One-electron oxidation and reduction of the germylidyne complex of 3-Ge in THF are electrochemically reversible suggesting that both the radical cation and radical anion of 3-Ge are accessible species in solution.

Detailed studies of the reactivity of the NHC-stabilized (NHC = N-heterocyclic carbene) silicon(II) halides SiI2(Idipp) (1) and SiClR(IMe4) (2-Trip: R = ArTrip; 2-Mes: R = ArMes) towards diazoalkanes and azides are presented (Idipp = C[N(C6H3–2,6-iPr2)CH]2, IMe4 = C[N(Me)CMe]2, ArTrip = C6H3-2,6-Trip2, ArMes = C6H3-2,6-Mes2, Trip = C6H2-2,4,6-iPr3, Mes = C6H2-2,4,6-Me3). Treatment of 1, 2-Trip, and 2-Mes with the diazoalkanes (p-Tol)2CN2 (p-Tol = C6H4-4-Me) and ArMesCHN2 afforded the NHC-stabilized silazines SiI2{N2C(p-Tol)2}(Idipp) (3) and SiClR{N2CH(ArMes)}(IMe4) (4-Trip: R = ArTrip, 4-Mes: R = ArMes) as orange to yellow solids, respectively. No N2 elimination from the diazoalkanes was observed in these reactions. In comparison, the reactions of 1 or 2-Trip with the covalent azides MesN3 or Me3SiN3, yielded after N2 elimination the yellow to colorless NHC-stabilized silaimines SiI2(NMes)(Idipp) (5), Si(ArTrip)Cl(NMes)(IMe4) (6) and Si(ArTrip)(N3)(NSiMe3)(IMe4) (7), respectively. All compounds were characterized by elemental analyses, FT-IR and multinuclear magnetic resonance spectroscopy. Moreover, the molecular structures of 4-Mes, 5, 6, and 7 were determined by single-crystal X-ray diffraction analyses.

Recently, the first synthetic route to 1,2-oxaphosphetane complexes was described, but the formation of too many isomers was a clear drawback and hampered further studies. Herein, we present significant advances with this problem using trifluoromethyl epoxide (4), 1,1′-bis(trifluoromethyl) epoxide (5), and differently substituted Li/Cl phosphinidenoid complexes 1–3 (R = CH(SiMe3)2, CPh3, C5Me5), thus giving 1,2-oxaphosphetane complexes 6–10 with high selectivity.

The Friedlander condensation reaction was employed to synthesize the new bidentate ligands namely 6-bromo-4-phenyl-2-pyridin-2-yl-quinoline (1) and 4-(4-phenyl-2-(pyridin-2-yl)quinolin-6-yl)phenol (2). These compounds were fully characterized including the X-ray structures of 1 and the protonated form of 2, i.e. 2·HCl·H2O. We also report the synthesis and spectroscopic characterization of two rhodium(III) complexes of the general formula [Rh(1)Cl3(CH3OH)] (3) and [Rh(2)Cl3(CH3OH)] (4). The molecular structures of 3·2CH3OH and 4 were determined by single-crystal X-ray diffraction studies, revealing that these complexes adopt the mer-configuration. The solution stability of 3, 4 was studied by a combination of UV–Vis and 1H NMR spectroscopic techniques. All compounds were biologically evaluated for their anti- platelet activity using their potency to inhibit the action of PAF (Platelet-Activating Factor), which is an approach of continuous interest in the field. Complexes 3 and 4 were found to be potent PAF inhibitors with IC50 values in the micromolar range (1.0 μM and 3.9 μM respectively). Since PAF is the most potent inflammatory lipid mediator, the PAF-inhibitors and consequently the title compounds may be considered as potent examples in the search for novel anti-inflammatory drugs.

Readily available P-tBu substituted Li/Cl phosphinidenoid complexes react with carbonyl compounds to furnish sterically almost unhindered oxaphosphirane complexes that reveal new and surprisingly facile intra- and intermolecular ring expansion reactions. 1,3,2-Dioxaphosphole complex formation is explained by DFT calculations through diastereoselective carbonyl group-induced ring cleavage of an oxaphosphirane intermediate.

The reaction of Li/Cl phosphinidenoid tungsten(0) complex 2 [R = CH(SiMe3)2] with 1,3,4,5-tetramethylimidazol-2-ylidene (3) yielded the zwitterionic phosphaalkene complex 4. A comparative study on chloro- (5) or dichloro(organo)phosphane complexes 1 [R = CH(SiMe3)2] and NHC 3 revealed the formation of 4 at ambient temperature. First evidence for the formation of phosphinidenoid complex 7, having a C-Cl imidazolium cation, and its reaction with benzaldehyde to give oxaphosphirane complex 9 are presented. Furthermore, the first example of a formal exchange at the phosphorus center of an oxaphosphirane complex to give zwitterion 4 is demonstrated.

Two novel supramolecular meso-helicates have been synthesized and characterized by single-crystal X-ray diffraction, variable-temperature magnetic susceptibility measurements, NMR and UV/Vis spectroscopy, mass spectrometry and density functional theory (DFT) simulations. Both compounds show a considerably high stabilization of the high-spin state of the metal centres compared with other compounds with similar types of ligands. Whereas the pyridyl complex [Fe2L23] [L2 = N,N′-bis(pyridin-2-ylmethylene)benzene-1,3-diamine] exhibits the beginning of a spin transition at around 350 K, the imidazolyl complex [Fe2L13] [L1 = N,N′-bis(1H-imidazol-4-ylmethylene)benzene-1,3-diamine] still exhibits a high-spin configuration at 20 K. We applied DFT to characterize the molecular as well as solid states of both compounds. Although the low-spin state of both systems is stabilized by crystal packing, an additional stabilization of the high-spin state is induced by intramolecular interactions. This effect can be ascribed to mechanical strain in the backbone of the ligands hailing from very short CH–π interactions and being similar in effect to sterically demanding methyl groups.

From enantiomerically pure, planar chiral [2.2]paracyclophane amines a series of nitrogen acyclic carbenegold(I) complexes and nitrogen heterocyclic carbenegold(I) complexes are prepared by a modular template synthesis using isonitriles and amines. These chiral catalysts are tested in two reactions, the enantiotopos-selective furanyne cyclization and the enantioselective enyne cyclization. While excellent conversions could be achieved with these new catalysts, the enantioselectivities in only some cases are in the range of best known catalysts for these conversion.

The surprisingly complicated crystal structure of (bis(terpyridine))copper(II) tetraphenylborate [Cu(tpy)2](BPh4)2 (tpy = 2,2':6',2″-terpyridine) consists of six crystallographically independent [Cu(tpy)2](2+) complexes. At ambient temperature, five out of six [Cu(II)N6] chromophores appear to be compressed octahedra, while at 100 K, four exhibit elongated and only two compressed octahedral geometry. Temperature dependent single crystal UV/vis (100, 298 K) and EPR measurements (20, 100, 298 K) as well as AOM calculations suggest that the octahedra which show apparently compressed octahedral geometry (XRD) result from dynamic Jahn-Teller behavior of elongated octahedra [Cu(II)N6]. The detailed correlation of structural and spectroscopic data allows an understanding of the strongly solvent-dependent structures of the [Cu(tpy)2](2+) complex in solution.

Reaction of Li/Cl phosphinidenoid complexes 2a,b with diphenyl thioketone or N,N′-tetramethylthiourea yielded the bicyclic 1,2-thiaphospholane complex 4b or alkylidene(thioxo)phosphane complex 6a, ...

A comparative study on the stereoselective synthesis of O,P,C-cage complexes is described using oxaphosphirane M(CO)5 complexes (M = Cr, Mo) and acetaldehyde or benzaldehyde. All products were unambiguously characterized by elemental analysis, multinuclear NMR, IR, MS, and single-crystal X-ray diffraction studies. DFT calculations provide evidence for initial C–O bond cleavage of the oxaphosphirane ring, most likely assisted by the selective bond weakening effect arising upon preliminary van der Waals complex formation. Subsequent P → C rearrangement of the Cp* group affords a phosphinidene oxide complex as key intermediate, which is responsible for the highly diastereoselective anchoring of the carbonyl compound.

Two novel heterobimetallic complexes, a trigonal-bipyramidal and a cubic one, have been synthesized and characterized using the same C3-symmetric metalloligand, prepared by a simple subcomponent self-assembly strategy. Adopting the molecular library approach, we chose a mononuclear, preorganized iron(II) complex as the metalloligand capable of self-assembly into a trigonal-bipyramidal or a cubic aggregate upon coordination to cis-protected C2-symmetric palladium(II) or unprotected tetravalent palladium(II) ions, respectively. The trigonal-bipyramidal complex was characterized by NMR and UV–vis spectroscopy, electrospray ionization mass spectrometry (ESI-MS), and single-crystal X-ray diffraction. The cubic structure was characterized by NMR and UV–vis spectroscopy and ESI-MS.

Backbone (R′2N)2P-substituted imidazole-2-thiones 2a–c [(R′2N)2P-IMSR,R; IMSR,R = 1,3-dialkylimidazole-2-thione-4-yl, a: R = iPr, R′ = Et; b: R = Mes, R′ = Et, c: R = Me, R′ = iPr] were treated with PCl3 to synthesize R′2N(Cl)P-substituted imidazole-2-thiones 3a–c [R′2N(Cl)P-IMSR,R]. The P-chloro compounds 3a,b were used to explore the chemistry further, i.e. nucleophilic substitution at phosphorus using Ph2CHLi or fluorenyl lithium afforded compounds 4a–c [R′2N(R′′)P-IMSR,R; a: R = iPr, R′ = Et, R′′ = PH2CH; b: R = Mes, R′ = Et, R′′ = Flu c: R = iPr, R′ = Et, R′′ = Flu]. Compound 4c was used to access the P-borane adduct 5 [R′2N(R′′)(BH3)P-IMSR,R; R = iPr, R′ = Et, R′′ = Flu] and phosphinoyl-substituted imidazolium hydrogensulfate 6 [[R′2N(R′′)(O)P-IMHR,R]HSO4; IMHR,R = 1,3-dialkylimidazolium-4-yl, R = iPr, R′ = Et, R′′ = Flu]. Compounds 4a,b were transformed into the P-Cl compounds 7a,b [R′′(Cl)P-IMSR,R; a: R = iPr, R′′ = Ph2CH; b: R = Mes, R′′ = Flu] which represent potential starting materials for backbone phosphaalkenyl substituted imidazole-2-thiones. Compound 7a yielded the NHC-stabilized phosphenium salt 8 [[R′′(IMe4)P-IMSR,R]Cl; R = iPr, R′ = Et, R′′ = Ph2CH, IMe4 = 1,3,4,5-tetramethylimidazole-2-ylidene] in reaction with 1,3,4,5-tetramethylimidazole-2-ylidene (IMe4). Attempts to deprotonate 7a,b using nBuLi revealed that nucleophilic substitution of P–Cl to give the P-nBu product occurred preferentially, and dehydrochlorination to the phosphaalkene was not observed.

The synthesis and characterization of a series of new cationic gold(I) complexes with hydroxyl-functionalized N-heterocyclic carbene (NHC) ligands is described. They are valuable building blocks for further derivatization: as a first example, coupling with amino acids and a dipeptide, respectively, successfully results in amino acid and peptide conjugates that are hard to obtain by other synthetic routes.

The first example of a ring opening reaction of a 1,2-oxaphosphetane complex is reported, i.e., water in the presence of [Li(12-crown-4)]Cl furnished a C–OH functional phosphinito complex. Employment of the latter in ring forming reactions with Me2ECl2 (E = Si, Ge) using different nitrogen bases is also described.

InFeO3(ZnO)4 was prepared from binary oxides as starting materials at 1350 °C in sealed platinum tubes as an earth brown powder. Single crystals were grown from a K2MoO4 flux in sealed Pt-tubes using cooling rates of –0.1 K min–1. The structure of InFeO3(ZnO)4 was refined in space group P63/mmc; No. 194 (a = 3.211(6) A; c = 33.032(6) A; Z = 2; R1 = 3.68 %) from XRD data and revealed a build-up from alternate stacking of layers of edge-sharing InO6 octahedra and 5 layers of corner-sharing (Zn/Fe)O4 tetrahedra. Inversions of the (Zn/Fe)O4 tetrahedra occurs (i) at the InO6 octahedral layer and (ii) halfway in the wurtzite type region where the inversion boundary is built by cations in 4+1 trigonal bipyramidal coordination. The position of the cations in their oxygen surrounding is described by a factor t which quantifies the displacement of the cation from the center of a trigonal bipyramid towards one of the constituting tetrahedra. Refining the site occupation factors of the cations in the (Zn/Fe)O4 tetrahedra results in a clear and reasonable gradient for the distribution of iron. Refinement of the oxygen position reveals split positions for the oxygen atoms at the second inversion boundary in the center of the wurtzite type region which shows similarities to inversion domain boundaries at fivefold coordinated cations in the wurtzite type region of compounds of type ARO3(ZnO)m with m > 15. Thus, it is more likely to describe InFeO3(ZnO)4 as a closest-packed structure of cations with oxygen filling the interstices.

The synthesis and structures of RhI and IrI complexes bearing 4-phosphinoyl- and 4,5-bis(phosphinoyl)imidazol-2-ylidene ligands (NHCP) is reported. Deprotonation of the corresponding imidazolium hydrogen sulfate salts by KOtBu in the presence of [M(cod)Cl]2 afforded complexes of the formula [M(cod)Cl(NHCP)] [5a/5b: NHCP = 4-Ph2P(O)-IiPrMe, 5a: M = Rh, 5b: M = Ir and 7a/7b: NHCP = 4,5-{Ph2P(O)}2-InBuMe]. The RhI complexes 5a and 7a were then converted into [Rh(CO)2Cl(NHCP)] 8a and 9a via reaction with carbon monoxide; the average CO stretching frequencies [8a: (CO)av = 2036 cm–1 and 9a: (CO)av = 2038.4 cm–1] led to the conclusion that mono- and bis-functionalized NHCPs act as relatively weaker donors than backbone unsubstituted NHC. A first examination of Janus-head ligand properties of complex 7a revealed that reaction with TiCl4 afforded hetero-dinuclear 10a,a′ as a mixture of isomeric monodentate phosphinoyl titanium(IV) adducts. All products were characterized by elemental analyses, spectroscopic and spectrometric methods and, in addition, complexes 7a and 7b by single-crystal X-ray structure analysis.

Single crystals of InGaZnO4 were synthesized in a sealed Pt-tube at elevated temperatures under normal pressure without flux. InGaZnO4 has a trigonal crystal system ( R 3 ¯ m ; No. 166) deduced from convergent beam electron diffraction (CBED). Single crystal structure refinement from XRD data at −150 °C (a=3.275(1) A; c=25.99(1) A; Z=3) revealed an alternate stacking of InO 6 / 3 − and ( Ga , Zn ) O 4 / 4 + layers, iso-structural to YbFe2O4. The cell parameters at room temperature were refined from powder X-ray diffraction data (a=3.284(3) A and c=26.037(3) A). The transparent crystals have a gray-bluish color and exhibit an excess of Ga expressed by the cation ratio of In:Ga:Zn=30.2(9):39(1):31(1) determined by energy dispersive X-ray spectroscopy (EDXS). While the isovalent substitution of In3+ by Ga3+ is known, an additional aliovalent substitution of Zn2+ by Ga3+ is observed. This results in the formula (In0.9Ga0.1)Ga1.06Zn0.91□0.03O4 where 3% of the cations in 4+1 coordination are vacant due to aliovalent substitution. Further evidence of that defect structure is found in the lattice parameter a which is substantially smaller than in stoichiometric InGaZnO4, as well as in the strong absorption in the near-IR from transitions correlated with the defect structure. The bluish color of the crystals is due to an enhanced absorption in the red of the visible spectrum. For the first time, we achieved to image InGaZnO4 at atomic resolution in the electron microscope proving a perfect periodic stacking of atomic layers.