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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 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 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 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.

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).

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 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.

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.