Search

The reaction of [{Ir(µ-Cl)(coe)2}2] (1, coe = cis-cyclooctene) with the bulky tertiary phosphane P(o-tolyl)3 in dichloromethane at room temperature was investigated. It afforded in good yield the tri-coordinate iridium(I) complex [IrCl{P(o-tolyl)3}2] (2) which was characterized in the solid state by a single-crystal X-ray diffraction study revealing a molecular structure of a rare tri-coordinate complex. The iridium(I) complex is stabilized by an agostic interaction of a hydrogen atom from the methyl group of the bulky phosphane ligand to fill the fourth unsaturated coordination site. The title compound crystallized from dichloromethane/diethyl ether as orange crystals in a mixture of two modifications (monoclinic P21/c, 2a, and orthorhombic Pbca, 2b). The co-existence of the two components as a nearly 1:1 mixture in the crystalline bulk material was supported by solid-state 31P{1H} NMR measurements.

The synthesis of [Rh2(η5‐Cp)2(μ‐H)(μ‐PPh2)2]BF4 (2) by protonation reaction of the metal basic complex [Rh2(η5‐Cp)2(μ‐PPh2)2] (1) with tetrafluoroboric acid in diethyl ether is described. Complex salt 2 was obtained in high yield and fully characterized by spectroscopic means and X‐ray crystal diffraction. Applying the isolobal analogy between H and the fragment Au(PPh3) as a synthetic strategy on the reaction of compound 2 with equimolar amounts of [Au(CH3)(PPh3)] in refluxing acetone resulted in the formation of the expected triangular cluster compound [Rh2{μ‐Au(PPh3)}(η5‐Cp)2(μ‐PPh2)2]BF4 (3) in good yield. Metal cluster salt 3 was fully characterized by spectroscopic data and its molecular structure in the crystal was determined by X‐ray diffraction. The structural comparison of the protonated dirhodium core in the cationic complex of 2 with the Rh2Au framework in 3 is in good accordance with the isolobal relation between H+ and Au+ because they share the respective same position in these closely related molecular structures.

The different coordination behavior of the flexible yet sterically demanding, hemilabile P,N ligand bis(quinoline-2-ylmethyl)phenylphosphine (bqmpp) towards selected Cu

The reaction of equimolar amounts of [Co(CO)3(NO)] and [PPN]CN, PPN+ = (PPh3)2N+, in THF at room temperature resulted in ligand substitution of a carbonyl towards the cyanido ligand presumably affording the complex salt PPN[Co(CO)2(NO)(CN)] as a reactive intermediate species which could not be isolated. Applying the synthetic protocol using the nitrosyl carbonyl in excess, the title reaction afforded unexpectedly the novel complex salt PPN[Co2(μ‐CN)(CO)4(NO)2] (1) in high yield. Because of many disorder phenomena in crystals of 1 the corresponding NBu4+ salt of 1 has been prepared and the molecular structure of the dinuclear metal core in NnBu4[Co2(μ‐CN)(CO)4(NO)2] (2) was determined by X‐ray crystal diffraction in a more satisfactory manner. In contrast to the former result, the reaction of [PPN]SCN with [Co(CO)3(NO)] yielded the mononuclear complex salt PPN[Co(CO)2(NO)(SCN‐κN)] (3) in good yield whose molecular structure in the solid was even determined and its composition additionally confirmed by spectroscopic means.

The reaction of the cyclometalated five‐coordinate 16 VE iridium(III) compound [IrCl(H)(P(tBu)2C6H4‐κ2P,C)(P(tBu)2Ph)] (1) with the strong π‐acceptor ligand trifluorophosphane resulted quickly in the quantitative formation of the new iridium(I) complex trans‐[IrCl(PF3)(P(tBu)2Ph)2] (2). This unexpected spontaneous reductive elimination was already observed in reactions of 1 with the very strong π‐acceptor ligands CO and NO+. First indications during reactions of 1 with lesser strong π‐acceptor ligands like alkyl or arylphosphanes did not show this inversion behavior of the cyclometalation. The title species 2 was characterized by spectroscopic methods and its molecular structure in the crystal was confirmed by X‐ray crystallography.

The reaction of [RhCp(coe)(2)] (1, coe = cis-cyclooctene) with one equivalent of the secondary phosphines PR2H in refluxing toluene afforded in situ the new complexes [RhCp(coe)(PR2H)] (R = Ph, 2a; R = o-tolyl, 2b; R = tBu, 2c) in good yields. Further thermolysis of 2a and 2b, respectively, in refluxing xylene resulted in the formation of the dinuclear doubly phosphanyl-bridged rhodium(II) species [{RhCp(mu-PR2)}(2)] (3a and 3b). This thermolytic approach does not work in the case of 2c since the tBu substituents increase the electron density on the rhodium center and impede, therefore, the loss of the olefinic ligand presumably caused by a stronger back donation effect. On the way from 2a to 3a the intermediate rhodium(III) complex [{RhCp(mu-PPh2)(H)(2)}(2)] (4a) was isolated. All new compounds were fully characterized by spectroscopic methods as well as by X-ray crystallography in the case of 3a, 3b and 4a confirming their molecular structures in the crystal. The compound [{RhCp(mu-PPh2)}(2)] did not react with dihydrogen at ambient conditions and not even in refluxing toluene affording the complex 4a by oxidative addition as originally assumed.

Treatment of THF solutions containing the rhodium(II) complex trans-[RhCl2(P t Bu2Ph)2] (1) with [Fe2(CO)9] in the same solvent resulted in the formation of the Vaska-type complex trans-[RhCl(CO)(P t Bu2Ph)2] (2) in high yield. The title complex 2 was obtained as pale yellow crystals, characterized by NMR and IR spectroscopy, as well as by microanalyses. Additionally, the molecular structure of 2 has been established by X-ray crystallography. As often reported for similar constituted compounds, the chlorido and carbonyl ligands in crystals of 2 are strongly disordered.

The synthesis of [Rh2(η5‐Cp)2(μ‐H)(μ‐PPh2)2]BF4 (2) by protonation reaction of the metal basic complex [Rh2(η5‐Cp)2(μ‐PPh2)2] (1) with tetrafluoroboric acid in diethyl ether is described. Complex salt 2 was obtained in high yield and fully characterized by spectroscopic means and X‐ray crystal diffraction. Applying the isolobal analogy between H and the fragment Au(PPh3) as a synthetic strategy on the reaction of compound 2 with equimolar amounts of [Au(CH3)(PPh3)] in refluxing acetone resulted in the formation of the expected triangular cluster compound [Rh2{μ‐Au(PPh3)}(η5‐Cp)2(μ‐PPh2)2]BF4 (3) in good yield. Metal cluster salt 3 was fully characterized by spectroscopic data and its molecular structure in the crystal was determined by X‐ray diffraction. The structural comparison of the protonated dirhodium core in the cationic complex of 2 with the Rh2Au framework in 3 is in good accordance with the isolobal relation between H+ and Au+ because they share the respective same position in these closely related molecular structures., The structural comparison of the metal cores of two new crystallographically characterized compounds [Rh2(η5‐Cp)2(μ‐H)(μ‐PPh2)2]BF4 (2) and [Rh2{μ‐Au(PPh3)}(η5‐Cp)2(μ‐PPh2)2]BF4 (3) confirmed the validity of the isolobal relationship between the fragments H and Au(PPh3).

The reaction of [Ru-3(CO)(12)] with P(o-tolyl)(2)H (molar ratio of 1 to 2) in refluxing THF afforded the electron-precise metal cluster [Ru-3(-H)(2)(-P{o-tolyl}(2))(2)(CO)(8)] (3). This reaction behavior is comparable to that using the secondary phosphane PtBu2H operating with the same molar ratio. As shown in earlier work, the ruthenium carbonyl reacted with an excess of PtBu2H under similar conditions with cluster degradation affording the coordinatively unsaturated complex [Ru-2(-H)(-PtBu2)(PtBu2H)(2)(CO)(4)]. We found that the reaction using similar reaction conditions with P(o-tolyl)(2)H in excess did not result in such a reactive dinuclear species. Here compound 3 was formed in a first step, which reacted with excess of the phosphane affording the new cluster [Ru-3(-H)(2)(-P{o-tolyl}(2))(2)(P{o-tolyl}(2)H)(2)(CO)(6)] (2). The molecular structures of 2 and 3 in the solid were confirmed by single-crystal X-ray analysis. Moreover, the P-31 NMR spectra of the new compounds showed coalescence phenomena on the NMR time scale caused by a restricted rotation about the P-C bonds, and, presumably, about Ru-P bonds, within the phosphane and phosphanido ligands.

The synthesis and structural characterization of the new olefinic complex [Rh(η 5-C5H5)(coe)(PtBu2H)] (2, coe = cis-cyclooctene) is reported. The title compound was easily prepared in good yield by a thermolytic approach using [Rh(η 5-C5H5)(coe)2] (1) and the secondary phosphane in toluene under reflux conditions. The compound 2 has been characterized by NMR spectroscopy and microanalysis. Single crystals of 2 were grown from n-hexane and the molecular structure has been established by X-ray diffraction.

The synthesis and structural characterization of bis-cyclometalated compounds [Ir(dFppy)2(Me4phen)]PF6 (4) and [Ir(dF(CF3)ppy)2(Me4phen)]PF6 (5) (dFppy = 2-(2,4-difluorophenyl)pyridinato, dF(CF3)ppy = 2-(2,4-difluorophenyl)-5-(trifluoromethyl)pyridinato, Me4phen = 3,4,7,8-tetramethyl-1,10-phenanthroline) were described, and their molecular structures were confirmed by single-crystal X-ray diffraction. Both compounds 4 and 5 show intense bluish-green luminescence in a diluted solution of organic solvents. The ligand change from dFppy in 4 to dF(CF3)ppy in 5 causes a significant change in the emission-decay kinetics, increasing the observed radiative rate by 4.5 times, despite the emission wavelength experiences, only a very moderate shift. The photophysical effects are rationalized by the interplay of different emitting excited states associated with different ligand-character contributions.

Treatment of hydrated ruthenium(III) chloride with tetra-2-pyridyl-1,4-pyrazine (tppz) in refluxing ethoxyethanol afforded the homoleptic dinuclear complex [(tppz)Ru(μ-tppz)Ru(tppz)]4+ (1) besides small amounts of the species [Ru(tppz)2]2+. The title complex 1 was obtained as purple crystals and characterized as its hexafluoridophosphate salt by NMR spectroscopy, mass spectrometry and microanalyses. The molecular structure of 1(PF6)4 has been established by X-ray crystallography.

Reactions of [{M(-Cl)(coe)(2)}(2)] (M = Rh, Ir;coe = cis-cyclooctene) with the secondary phosphane tBu(2)PH under various molar ratios were investigated. Probably, for kinetic reasons, the reaction behavior of the rhodium species differed from that of the iridium analogue in some instances. During these studies complexes [MCl(tBu(2)PH)(3)] [M = Rh (1), Ir (2)] were isolated, and solution variable-temperature P-31{H-1} NMR studies revealed that these complexes show a conformational rigidity on the NMR time scale. Spectra recorded in the temperature range from 173 to 373 K indicated in each case only one rotamer containing three chemically nonequivalent phosphanes due to the restricted rotation of these ligands about the M-P bonds and the tert-butyl substituents around the P-C(tBu) bonds, respectively. Compound 1 showed in solution already at room temperature in several solvents a dissociation of a phosphane ligand affording the known complex [{Rh(-Cl)(tBu(2)PH)(2)}(2)] beside the free phosphane. In contrast to these findings, the iridium analogue 2 remained completely unchanged under similar conditions and exhibited, therefore, some kinetic inertness. For a better understanding of the NMR spectroscopic investigations, the molecular structure of 1 in the solid state was confirmed by X-ray crystallography.

Reactions of the Collman reagent, Na2[Fe(CO)4]·1.5 dioxane, towards the nitrosyl carbonyls [CoNO(CO)3] and [Fe(NO)2(CO)2] in THF as the solvent at room temperature were investigated. Thereby a quick transfer of one nitrosyl ligand from the nitrosyl carbonyl molecule to the iron carbonyl metalate was observed. The reaction with the cobalt compound afforded in high yields the well-known species [Co(CO)4]− and [FeNO(CO)3]− isolated by addition of two equivalents of [PPN]+Cl− ([PPN]+= bis(triphenylphosphane)iminium cation) and characterized by their known IR spectra, by elemental analysis and their characteristic colors and melting points. In the reaction of the Collman reagent with [Fe(NO)2(CO)2] a clean transformation to the tricarbonylnitrosylferrate(1−) as the only formed product was observed.

The synthesis and structural characterization of the new olefinic complex [Rh(eta(5)-C5H5)(coe)(2)] (2) (coe = cis-cyclooctene) is reported. The title compound could easily be prepared in good yield by reaction of [{Rh(mu-Cl)(coe)(2)}(2)] (1) with an appropriate amount of thallium cyclopentadienide in THF at room temperature. Single crystals of 2 were grown from n-hexane and were analyzed by X-ray crystallography. In a similar manner the compound [Rh(eta(5)-C5H5)(cod)] (4) (cod = cis, cis-1.5-cyclooctadiene) was obtained from [{Rh(mu-Cl)(cod)}(2)] and thallium cyclopentadienide in THF at room temperature and was characterized by spectroscopic means as well as by X-ray diffraction.

The reaction of the nitrosyl carbonyl complexes [Fe(NO)(2)(CO)(2)] and [Co(NO)(CO)(3)] with the decacarbonyldimetalates [M-2(CO)(10)](2-) (M = Cr and Mo) in THF as the solvent at room temperature was investigated. Thereby a substitution of one nitrosyl ligand towards carbon monoxide was observed in each case. Both reactions afforded the known metalate complexes [Fe(NO)(CO)(3)](-) and [Co(CO)(4)](-), respectively. These species were isolated as their corresponding PPN salts [PPN+ = bis(triphenylphosphane)iminium cation] in nearly quantitative yields. The products were unambiguously identified by their IR spectroscopic and elemental analytic data as well as by their characteristic colors and melting points.

The reaction of [{Ir(μ-Cl)(coe)2}2] (coe=cis-cyclooctene) with triphenylphosphane (molar ratio of Ir to P=1 : 3) in dichloromethane at room temperature afforded after a short reaction time the cyclometallated complex [IrCl(H)(C6H4PPh2)(PPh3)2] (1) in almost quantitative yield. The molecular structure of the title compound 1 was determined by an X-ray diffraction study.

The synthesis and structural characterization of trans-[IrCl(NO)(PtBu2H)(2)]BF4 (1) is reported. The title compound was prepared in good yield in the reaction of in situ-prepared trans-[IrCl(coe)(PtBu2H)(2)] (coe = cis-cyclooctene) with an appropriate amount of nitrosonium tetrafluoridoborate in dichloromethane at room temperature. Single crystals of 1 were grown from dichloromethane/diethyl ether and were analyzed by X-ray crystallography.

The synthesis and structural characterization of trans-[RhCl(NO)(PtBu2H)(2)]BF4 (2) is reported. The title compound could easily be prepared in good yields by a kind of bridge-splitting reaction of [{Rh(-Cl)(PtBu2H)(2)}(2)] (1) with an appropriate amount of nitrosonium tetrafluoridoborate in dichloromethane at room temperature. Single crystals of 2 were grown from dichloromethane/diethyl ether and were analyzed by X-ray crystallography.

The reaction of [Ru3(CO)12] with pivalic acid in acetonitrile afforded the coordinatively unsaturated complex [{Ru2(μ-O2CtBu)2(CO)4}n] (1) for which a so far unknown polymeric structure is assumed. Compound 1 showed in the solid as well as dissolved in non-polar aliphatic solvents and carbon tetrachloride, respectively, a deep violet color. In common organic solvents 1 is readily dissolved resulting in solutions exhibiting a yellow to orange color. On the one hand, in such solutions the polymeric structure of 1 is broken resulting in distinct compounds as the Ru2(μ-O2CtBu)2(CO)4 units coordinate two monodentate solvent molecules, as shown for [Ru2(μ-O2CtBu)2(CO)4(py)2] (3, py = pyridine), or they coordinate ligands like phosphanes, as shown for [Ru2(μ-O2CtBu)2(CO)4(PtBu2H)2] (4). On the other hand, in solutions of 1 the Ru2 frameworks are linked by coordination of multidentate solvent molecules resulting in a coordination polymer which was confirmed by the crystal structure determination of [{Ru2(μ-O2CtBu)2(CO)4(HOC2H4OEt)}n] (2).

Reactions of coordinatively unsaturated complexes [Ru2(μ-PtBu2)(μ-H)(μ-PˆP)(CO)4] (PˆP = bisphosphanes, N,N-substituted bis(diphenylphosphanyl)amines) with the nitrosylating reagent diazald (N-methyl-N-nitroso-p-toluenesulfonamide) were investigated. Thus a convenient synthesis affording a series of new diruthenium complexes containing bridging nitrosyl ligands of the general type [Ru2(μ-PtBu2)(μ-NO)(μ-PˆP)(CO)4] was developed and the crystal and molecular structures of five new compounds were determined. Contrary, this reaction principle does not work for the closely related complex [Fe2(μ-PtBu2)(μ-H)(μ-dppm)(CO)4] (dppm = Ph2PCH2PPh2). In this case carbon monoxide was produced in side reactions and the known compound [Fe2(μ-PtBu2)(μ-H)(μ-dppm)(μ-CO)(CO)4] was obtained as the main product. The molecular structure of the latter complex was also determined by X-ray diffraction.

The addition reaction of a proton towards the nitrosyl-bridged diruthenium complexes [Ru 2 (CO) 4 (μ-NO)(μ-P t Bu 2 )(μ-P^P)] (P^P = Me 2 PCH 2 PMe 2 , dmpm, 1b ; P^P = Ph 2 PC(=CH 2 )PPh 2 , dppen, 1c ; P^P = Ph 2 PN(H)PPh 2 , dppa, 1d ) has been investigated. The species 1b–d exhibit an enhanced metal basicity and react spontaneously with a proton (from HBF 4 ) in diethyl ether to afford the corresponding oxidative addition products [Ru 2 (CO) 4 (μ-NO)(μ-H)(μ-P t Bu 2 )(μ-P^P)]BF 4 ( 2b–d ) in good yields. The molecular structures of 2b – d were confirmed by X-ray diffraction studies revealing a shortening of the metal–metal bond upon protonation in each case.

The synthesis, crystal structure, and photophysical properties of the novel bis-cyclometalated complex Λ,Δ-[Ir2(μ-biuretato-N,N′:O,O′)(ptpy)4] (2), with ptpy = 2-(p-tolyl)pyridinato, prepared in the reaction of [{Ir(μ-Cl)(ptpy)2}2] (1) with biuret under basic conditions, were investigated. This new compound displays intense green phosphorescence, e.g. with λem = 518 nm, ɸPL = 55%, and τ = 1.5 μs in poly(methyl methacrylate) at 300 K, assigned to a 3MLCT/LC excited state.

A convenient synthesis of cyclometalated complexes [{Rh(μ-Cl)(C N)2}2] [C N = ppy, 2-phenylpyridinato (2); C N = ptpy, 2-(p-tolyl)pyridinato (3); 4-Clppy = 4-chloro-2-phenylpyridinato (4)] at room temperature is described. The compounds were obtained by the oxidative addition reaction of the corresponding 2-phenylpyridines to [{Rh(μ-Cl)(coe)2}2] (1) (coe = cis-cyclooctene) in dichloromethane solution. The rate of the reaction seems to depend on the electronic influence of the substituents on the phenyl rings of the corresponding 2-phenylpyridines. The analogous iridium complex of 1 reacted markedly only at higher temperatures in suitable solvents under cyclometalation. The molecular structure of the new compound 4 was additionally confirmed by an X-ray diffraction study.

The synthesis and structural characterization of the complex [Ru2(μ-Cl)(μ-PtBu2)(μ-dppa)(CO)4] (4, dppa = Ph2PN(H)PPh2) are reported. The title compound and two other related complexes were obtained in high yields by the reaction of the coordinatively unsaturated species [Ru2(μ-H)(μ-PtBu2)(μ-PˆP)(CO)4] (PˆP = dppa, 3; PˆP =Ph2PN(Ph)PPh2, 5; PˆP =Ph2PN(CH2Ph)PPh2, 6) with carbon tetrachloride. Single crystals of 4 grown from dichloromethane-acetone have been analyzed by X-ray crystallography

The addition reaction of a proton towards the coordinatively unsaturated diruthenium complexes [Ru 2 (CO) 4 (μ-H)(μ-P t Bu 2 )(μ-P^P)] (Ru Ru) (P^P = Ph 2 PC( CH 2 )PPh 2 , dppen, 1b ; P^P = Ph 2 PN(H)PPh 2 , dppa, 1c ; P^P = Ph 2 PN(Ph)PPh 2 , dpppha, 1d ) has been investigated. Thus the species 1b–d exhibit a high metal basicity and react with protons from tetrafluoroboric acid in dichloromethane to afford the corresponding oxidative addition products [Ru 2 (CO) 4 (μ-H) 2 (μ-P t Bu 2 )(μ-P^P)]BF 4 ( 2b–d ) in good yields. During these reactions a shortening of the metal–metal bond in each case was observed as confirmed by X-ray diffraction studies.

The synthesis of the bis-cyclometalated complexes [M(ptpy)2(S2COCH3)] (M = Rh, 1; M = Ir, 2; ptpy = 2-(p-tolyl)pyridinato) from [{M(μ-Cl)(ptpy)2}2], carbon disulfide and sodium methanolate as the base are described. Compound 1 and 2, respectively, were crystallized from dichloromethane/methanol and the molecular structures of both complexes were confirmed by single-crystal X-ray diffraction studies (both monoclinic, P21/c). The emission spectrum of 1 exhibited the new compound as a red-emitting complex.

The reaction of the trans-hyponitrito complex [Ru2(CO)4(μ-η2-ONNO)(μ-H)(μ-PtBu2)(μ-dppen)] (1, dppen = Ph2PC(=CH2)PPh2) with tetrafluorido boric acid afforded the new complex salt [Ru2(CO)4(μ-η2-ONNOH)(μ-H)(μ-PtBu2)(μ-dppen)]BF4 (2) containing the monoprotonate hyponitrous acid as the ligand in the cationic complex. Complex 1 showed a nucleophilic reactivity towards the trimethyloxonium cation resulting in the monoester derivative of the hyponitrous acid [Ru2(CO)4(μ-η2-ONNOMe)(μ-H)(μ-PtBu2)(μ-dppen)]BF4 (3). During heating of compound 2 in ethanol under reflux for a short time nitrous oxide was liberated affording unexpectedly a new tridentate 2, 2-bis(diphenylphosphanyl)ethanolato ligand formed by an intramolecular attack of an intermediate hydroxido ligand towards the unsaturated carbon carbon double bond in the bridging dppen ligand. Thus the complex salt [Ru2(CO)4{μ-η3-OCH2CH(PPh2)2}(μ-H)(μ-PtBu2)]BF4 (4) was formed in good yields. The new compounds 2, 3, and 4 were characterized by spectroscopic means as well as their molecular structures were determined in the crystal.

The synthesis and the characterization of the complex salt [Au(tBu2PH)2][HCl2] (2) resulting from the reaction of hydrogen tetrachloridoaurate(III) hydrate with tBu2PH in dichloromethane at room temperature is reported. Single crystals of 2 have been analyzed by X-ray crystallography: monoclinic, P21=c, Z = 12, a = 12:0805(3), b = 12:3729(4), c = 46:7506(13) Å ; ß = 90:948(2)°; V = 6986:9(3) Å3; T = 173(2) K. The hydrogen bihalide anions [HCl2]- fill the interstices between the large complex cations [Au(tBu2PH)2]+ in the crystal.

The reaction of the electronically and coordinatively unsaturated compounds [Ru 2 (CO) 4 ( μ -H)( μ -PBu t 2 )( μ -L 2 )] ( 1 ) (Ru Ru) with nitric oxide afforded four new trans -hyponitrito complexes of the general formula [Ru 2 (CO) 4 ( μ -H)( μ -PBu t 2 )( μ -L 2 )( μ - η 2 -ONNO)] ( 2 ) in good yields. Thus the complexes 2a – e were obtained using the following bridging biphosphane ligands ( μ -L 2 ): dppm ( 2a , dppm = Ph 2 PCH 2 PPh 2 ), dppen ( 2b , dppen = Ph 2 PC( CH 2 )PPh 2 ), dpppha ( 2c , dpppha = Ph 2 PN(Ph)PPh 2 ), dpppra ( 2d , dpppra = Ph 2 PN(Pr n )PPh 2 ), and dppbza ( 2e , dppbza = Ph 2 PN(CH 2 Ph)PPh 2 ). The molecular structures of the complexes 2a – e were determined by X-ray diffraction. Furthermore the molecular structure of the known compound 2a was reinvestigated in light of a better refinement of the short intramolecular contact between the hyponitrite O atom in close vicinity to the C atom of a neighbouring carbonyl group. This unusual effect in crystals of all compounds 2a – e can be interpreted as a nucleophilic intramolecular attack of a hyponitrito ligand towards an electrophilic carbon center of a carbonyl ligand.

The synthesis of the trans-hyponitrite compounds Ph3E(μ-ONNO)EPh3 [E = Ge (1), Pb (2)] as well as their crystal and molecular structure are reported. Compound 1 crystallized from toluene/pentane in the trigonal space group R with a = 29.7969(18), b = 29.7969(18), c = 11.8465(6) A; γ = 120°; V = 9108.8(9) A3; Z = 12, ρ = 1.461 g·cm–3,T = 173(2) K. Compound 2 crystallized from toluene/iso-hexane in the triclinic space group P with a = 10.0330(2), b = 11.0615(2), c = 24.2080(4) A; α = 97.3730(10), β = 95.8550(10), γ = 115.3940(10)°; V = 2369.69(7) A3; Z = 3, ρ = 1.970 g·cm–3, T = 173(2) K.The crystal structure determination revealed that two conformational isomers exist in the row of related group 14 element compounds. Whereas the species of tin and lead exhibit a S-shaped arrangement of the hyponitrite group between the two EPh3 fragments, the corresponding germanium compound shows instead of a N-shape within the hyponitrite group. DFT calculations revealed that S-shaped conformers should be in all three cases the more stable ones. This stands in contrast to the observed N conformation of 1 in the crystal.

A convenient synthesis and the characterization of six new electronically and coordinatively unsaturated complexes of the formula [Ru2(CO)4(μ-H)(μ-PtBu2)(μ-L2)] (2b–g) (Ru Ru) is described exhibiting a close relation to the known [Ru2(CO)4(μ-H)(μ-PtBu2)(μ-dppm)] (2a). The complexes 2b–g were obtained in a kind of one-pot synthesis starting from [Ru3(CO)12] and PtBu2H in the first step followed by the reaction with the bidentate bridging ligand in the second step. The method was developed for the following bridging ligands (μ-L2): dmpm (2b, dmpm = Me2PCH2PMe2), dcypm (2c, dcypm = Cy2PCH2PCy2), dppen (2d, dppen = Ph2PC(=CH2)PPh2), dpppha (2e, dpppha = Ph2PN(Ph)PPh2), dpppra (2f, dpppra = Ph2PN(Pr)PPh2), and dppbza (2g, dppbza = Ph2PN(CH2Ph)PPh2). The molecular structures of all new complexes 2b−g were determined by X-ray diffraction.

The reaction of the coordinatively unsaturated complex [Ru2(CO)4(μ-H)(μ-PtBu2)(μ-dppm)] (1, dppm = Ph2PCH2PPh2)] with the nitrosonium ion was revisited. Even by variation of the reaction conditions, the reaction afforded in each case not the sole addition product [Ru2(CO)4(μ-NO)(μ-H)(μ-PtBu2)(μ-dppm)]+ (2) as reported by us in an earlier paper. Instead always a mixture of three compounds containing the complexes [Ru2(CO)4(μ-H)2(μ-PtBu2)(μ-dppm)]+ (3), [Ru2(CO)4(μ-NO)(μ-PtBu2)(μ-dppm)] (4), beside the originally described complex 2 was obtained. A new synthetic procedure affording compound 4 as the sole product by reaction of 1 with the nitrosylating reagent diazald (N-methyl-N-nitroso-p-toluenesulfonamide) is described. It was found that complex 2 can act as an acid strong enough to protonate the starting complex 1. Thus, the formation of the mixture of components in the title reaction could be explained. A mixing experiment of equimolar amounts of 1 and 2 showed unambiguously the formation of complexes 3 and 4. A clean preparation of complex 2 as the sole product in form of its tetrafluoridoborate salt is only possible by reaction of 4 with tetrafluoridoboric acid in diethyl ether solution. The X-ray crystal structure of [2]BF4 is reported confirming the molecular structure of the complex 2. Using the originally described preparation route for 2 afforded in each attempt of crystallization the complexes 2 and 3 as 1:1 mixture in the solid.

The reaction of [AuCl(tht)] (tht = tetrahydrothiophene) with an equimolar amount of the electron-rich ligand N-diphenylphosphino-triphenylphosphinimine, Ph3PNPPh2, in THF afforded the new complex [AuCl(Ph3PNPPh2)] (1) in good yield. Furthermore, the reaction of [AuHCl4] with Ph3PNPPh2 in a molar ratio of 1:3 in dichloromethane at room temperature yielded the complex salt [Au(Ph3PNPPh2)2]Cl (2) as the dichloromethane solvate beside Ph3PNPPh2Cl2 as the side-product of oxidation. The molecular structures of metal complexes 1 and 2 were determined by single-crystal X-ray diffraction. Because of the bulkiness of the ligand Ph3PNPPh2 no short intermolecular gold–gold interactions (aurophilic aggregation) could be observed in the solid-state structures.

A new convenient synthesis and the crystallographic characterization of [Ir(acac)(coe)2] (2, acac = acetylacetonato; coe = cis-cyclooctene) are described. The title compound crystallized from THF/ethanol in two modifications (monoclinic P21/c, 2a, and triclinic P 1 ¯ , 2b). Complex 2 represents an efficient starting material in the synthesis of mononuclear iridium(III) complexes containing cyclometalated 2-phenylpyridinato ligands using oxidative addition reactions of the corresponding ligands towards 2. Thus [Ir(acac)(ppy)2] (3, ppy = 2-phenylpyridinato) and [Ir(ppy)3] (4) (mer, 4a; fac, 4b) were prepared in excellent yields and short reaction times in a kind of one-pot procedure starting from [{Ir(μ-Cl)(coe)2}2] (1). Furthermore a convenient synthesis of [{Ir(μ-Cl)(ppy)2}2] (5) from 1 and Hppy is described.

The reaction of hydrated rhodium(III) chloride with formic acid in refluxing ethoxyethanol afforded in a convenient way the known rhodium carbonyl chlorido complex anion cis-[RhCl2(CO)2]-. This species was formed in good yield and was characterized as its PPN salt (PPN+ = bis(triphenylphosphane)iminium cation). The molecular structure of the title compound PPN[RhCl2(CO)2] was confirmed by X-ray diffraction and shown to be isomorphous to PPN[IrCl2(CO)2]