Synthese,Strukturuntersuchung und Reaktionen Phosphansubstituierter Derivate von Fe3(CO)9(μ3-CF)2

Syntheses, Structure Determination and Reactions of Phosphine Substituted Derivatives of Fe₃(CO)₉(μ₃-CF)₂ Photolysis of Fe₃(CO)₉(μ₃-CF)₂ 1 in the presence of acetonitrile 2a or benzoenitrile 2b results in the substitution of a single carbonyl ligand by a nitrile ligand yielding Fe₃(CO)₈(CH₃CN)(μ₃-CF)₂ 3a and Fe₃(CO)₈(C₆H₅CN)(μ₃-CF)₂ 3b, respectively. The acetonitrile ligand in 3a can be easily replaced by trimethyl-phosphine 4a or triphenylphosphine 4b . The monosubstituted compounds Fe₃(CO)₈(PR₃)(μ₃-CF)₂5, R = CH₃ a, R = C₆H₅, b are obtained as major products besides a small amount of the disubsituted products Fe₃(CO)₇(PR₃)₂(μ₃-CF)₂ 6. The structure of 5a has been elucidated by a single crystal X-ray structure determination. Thermal ligand substitution in 1, however, results in the formation of a mixture of mono-, disubstituted, and trisubstituted products, in which 6b is the major product for diphenylphosphine. 5a reacts with ethyne 7 forming a phosphine substituted diferra-allyl-cluster Fe₃(CO)₇(PR₃)(μ₃-CF)(μ₃? CF? CH? CH) 8. The structure of one isomere of 8 has been determinated by X-ray crystallography.     

Neue Azidokomplexe des Tantals(V). Synthese und Molekülstruktur der Zweikernverbindungen [Cp*TaCl(N3)(μ‐N3)]2(μ‐O) und [Cp*Ta(N3)3(μ‐N3)]2 (Cp* = Pentamethylcyclopentadienyl)

New Azido Complexes of Tantalum(V). Synthesis and Molecular Structure of the Dinuclear Compounds [Cp*TaCl(N₃)(μ‐N₃)]₂(μ‐O) and [Cp*Ta(N₃)₃(μ‐N₃)]₂ (Cp* = Pentamethylcyclopentadienyl) The reaction of Cp*TaCl₄ ( 1 ) with an excess of trimethylsilyl azide (Me₃Si–N₃) leads to azide‐rich dinuclear complexes which contain both terminal and bridging azido ligands. The oxo complex [Cp*TaCl(N₃)(μ‐N₃)]₂(μ‐O) ( 4 ) was formed in dichloromethane in the presence of traces of water, whereas [Cp*Ta(N₃)₃(μ‐N₃)]₂ ( 5 ) was obtained from boiling toluene after several days. According to the X‐ray structure determinations the Ta…Ta distance in 4 (314,5 pm) is considerably shorter than in 5 (382,2 pm).     

[Ph2P(O)CH2Im][F3B(μ‐OH)BF3]. Erste strukturanalytische Charakterisierung des Hexafluoro(μ‐hydroxo)diborat‐Ions [1]

[Ph₂P(O)CH₂Im][F₃B(μ‐OH)BF₃]. First Structural Characterization of the Hexafluoro(μ‐hydroxo)diborate Ion [1] The hexafluoro(μ‐hydroxo)diborate ion has been isolated as it's Ph₂P(O)CH₂Im salt [Im = 2‐(1, 3, 4, 5‐tetramethylimidazolio)] ( 2 ) through basic hydrolysis of [Ph₂P(OBF₃)CH₂Im]BF₄ ( 1 ). The crystal structure of 2 · CH₂Cl₂ reveals the presence of ion pairs linked by unsymmetrical O‐H‐O hydrogen bonds.     

[{Cp″Co}3(μ3-P)(μ3-PSe)], ein Dreikerncluster mit einem PSe-Liganden

[{Cp″Co}₃(μ₃-P)(μ₃-PSe)], a Trinuclear Cluster with a PSe Ligand The cothermolysis of [Cp″Co(CO)₂] ( 1 ), Cp″ = C₅H₃Bu-1.3, and P₄ gives besides [{Cp″Co}₃(μ₃-P)₂] ( 2 ) the cobalt P_n complexes [{Cp″Co}₄(μ₃-P)₄] ( 3 ) and [{Cp″Co}₂(μ, η^2:2-P₂)₂] ( 4 ). 2 can be oxidized with grey selenium forming [{Cp″Co}₃(μ₃-P)(μ₃-PSe)] ( 5 ) and [{Cp″Co}₃(μ₃-PSe)₂] ( 6 ), complexes with the hitherto unknown PSe ligand. The crystal structure of 5 reveals a trigonal-bipyramidal Co₃P₂ skeleton with one μ₃-PSe ligand.     

Molekül‐ und Kristallstruktur von Bis[chloro(μ‐phenylimido)(η5‐pentamethylcyclopentadienyl)tantal(IV)](Ta–Ta), [{TaCl(μ‐NPh)Cp*}2]

Molecular and Crystal Structure of Bis[chloro(μ‐phenylimido)(η⁵‐pentamethylcyclopentadienyl)tantalum(IV)](Ta–Ta), [{TaCl(μ‐NPh)Cp*}₂] Despite the steric hindrance of the central atom in [TaCl₂(NPh)Cp*] (Ph = C₆H₅, Cp* = η⁵‐C₅(CH₃)₅), caused by the Cp* ligand, the imido‐ligand takes a change in bond structure when this educt is reduced to the binuclear complex [{TaCl(μ‐NPh)Cp*}₂] in which tantalum is stabilized in the unusual oxidation state +4.