Coordinatively unsaturated molybdenum complexes with chelating cycloheptatrienyl-phosphane ligands and their use in transition metal catalysis

Tamm, Matthias; Dressel, B.; Urban, Victoria; Lügger, Thomas

doi:10.1016/s1387-7003(02)00587-7

Cited by 19 publications

(2 citation statements)

References 22 publications

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“…[10,11] Complexes with linked cycloheptatrienyl-phosphane ligands seemed to be particularly well suited for applications in catalytic CϪC coupling reactions, and so we have started to prepare precursor complexes that should allow us to obtain coordin-atively unsaturated molybdenum complex fragments of type II (Scheme 1). [12] …”

Section: Introductionmentioning

confidence: 99%

Chelate Complexes of Functionalized Cycloheptatrienyl Ligands: Molybdenum Complexes with Linked Cycloheptatrienyl‐Phosphane Ligands and Their Use in Catalytic Carbon−Carbon Bond Formation

et al. 2003

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The synthesis of P‐functionalized molybdenum chelate complexes incorporating the linked cycloheptatrienyl‐phosphane ligand [2‐(diisopropylphosphanyl)phenyl]cycloheptatrienyl (o‐iPr2P−C6H4−C7H6) is described. From the ligand precursor [2‐(cyclohepta‐2,4,6‐trienyl)phenyl]diisopropylphosphane (1) the paramagnetic 17‐electron dibromide [(o‐iPr2PC6H4‐η7‐C7H6)MoBr2(P−Mo)] (2) can readily be obtained. This is a versatile starting material for the preparation of cycloheptatrienyl molybdenum hydrides [(o‐iPr2PC6H4‐η7‐C7H6)Mo(η2‐BH4)(P−Mo)] (3) and [(o‐iPr2PC6H4‐η7‐C7H6)Mo(PPh3)H(P−Mo)] (4). Treatment of 3 with dimethylanilinium tetraphenylborate ([PhNMe2H][BPh4]) allows the production of the cationic 14‐electron complex fragment [(o‐iPr2PC6H4‐η7‐C7H6)Mo(P−Mo)]+ (13), which can be stabilized in the presence of suitable ligands L. The complexes [(o‐iPr2PC6H4‐η7‐C7H6)MoL2(P−Mo)]BPh4 [L = dimethylphenyl isocyanide, (5)BPh4; L2 = η4‐2,5‐norbornadiene, (6)BPh4; L2 = η2‐phenylacetylene, (7)BPh4; L2 = η2‐tert‐butylacetylene, (8)BPh4] can thus be isolated in good yields. The alkyne complex (7)BPh4 can be used as a single‐source catalyst for the oligomerization of phenylacetylene, affording a mixture of triphenylbenzenes and linear oligomers. Quantum chemical calculations reveal an intimate relationship between the catalytically active 14‐electron complex fragment [(o‐iPr2PC6H4‐η7‐C7H6)Mo(P−Mo)]+ (13) and hypothetical isoelectronic and isolobal complexes of the type [(o‐iPr2PC6H4‐η5‐C5H4)M(P−M)]+ (M = Ru, 14; M = Os, 15), indicating that cycloheptatrienyl molybdenum systems might in general be a suitable replacement for cyclopentadienyl ruthenium and osmium catalysts. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

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Section: Introductionmentioning

confidence: 99%

Chelate Complexes of Functionalized Cycloheptatrienyl Ligands: Molybdenum Complexes with Linked Cycloheptatrienyl‐Phosphane Ligands and Their Use in Catalytic Carbon−Carbon Bond Formation

et al. 2003

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“…In view of the growing number of well-characterized 16-electron cyclopentadienyl-ruthenium complexes, it is surprising that no analogous half-sandwich cycloheptatrienyl-molybdenum complexes have been reported to date, although the similarity between the isoelectronic and isolobal fragments [(η 5 -C 5 R 5 )Ru] and [(η 7 -C 7 H 7 )Mo] is well recognized. – The steric requirements of the C 7 H 7 (Cht) ligand (cone angle ≈ 154°) make comparison with the C 5 Me 5 (Cp*) system (cone angle ≈ 142°) particularly appropriate, and it could clearly be demonstrated that complexes of the 16-electron [(η 7 -C 7 H 7 )MoL 2 ] auxiliary exhibit reactivity patterns analogous to those of [(η 5 -C 5 Me 5 )RuL 2 ] systems. , In this contribution, we present the synthesis and structural characterization of stable cationic 16-electron molybdenum complexes of the type [(η 7 -C 7 H 7 )Mo(BL R )] + (R = Me, i Pr) containing the neutral 1,2-bis(imidazolin-2-imino)ethane ligands BL Me and BL i Pr and compare their properties with those of their [(η 5 -C 5 Me 5 )Ru(BL R )] + congeners …”

Section: Introductionmentioning

confidence: 99%

Synthesis and Reactivity of 16-Electron Cycloheptatrienyl-Molybdenum(0) Complexes with Bis(imidazolin-2-imine) Ligands

et al. 2008

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The reaction of the ligands 1,2-bis(1,3-diisopropyl-4,5-dimethylimidazolin-2-imino)ethane (BL iPr ) and 1,2-bis(1,3,4,5-tetramethylimidazolin-2-imino)ethane (BL Me ) with the cycloheptatrienyl-molybdenum complex [(η 7 -C 7 H 7 )Mo(CH 3 CN) 3 ]X (X ) BF 4 , PF 6 ) leads to acetonitrile substitution and formation of stable 16-electron half-sandwich complexes (η 7 -C 7 H 7 )Mo(BL iPr )]BF 4 , [1]BF 4 , and [(η 7 -C 7 H 7 )Mo(BL Me )]X, [2]X (X ) BF 4 , PF 6 ), two of which could be crystallographically characterized to reveal undistorted two-legged piano stool geometries. Cyclovoltammetric studies exhibit very negative redox potentials of E°) -1.095 V and E°) -1.138 V versus the ferrocene/ferrocenium couple (0 V), indicative of very electron-rich metal complexes. Oxidation of [2]X with (η 7 -C 7 H 7 )BF 4 or [Fe(η 5 -C 5 H 5 ) 2 ]PF 6 furnished the Mo(I) complexes of general formula [(η 7 -C 7 H 7 )Mo(BL Me )(CH 3 CN)]X 2 , [3]X 2 (X ) BF 4 , PF 6 ), which display a three-legged piano stool geometry in the solid state by coordination of one additional acetonitrile molecule to molybdenum. The same geometry is observed upon reaction of [1]BF 4 and [2]PF 6 with 2,6dimethylphenyl isocyanide (XyNC) to afford the isocyanide complexes [1(CNXy)]BF 4 and [2(CNXy)]PF 6 . Their CN stretching vibrations are observed at 2041 and 2030 cm -1 , confirming the electron richness and strong π-electron-releasing capability of the molybdenum-imine moiety.

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Ansa‐Cycloheptatrienyl–Cyclopentadienyl Complexes

et al. 2004

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Die Einführung der Me2Si‐Brücke und die Verzerrung der Sandwichstruktur erleichtern die Wechselwirkung des 16‐Elektronen‐ansa‐Komplexes (siehe Bild; blau Ti, gelb Si, grau C) mit σ‐Donor/π‐Acceptorliganden wie CO oder Isocyaniden. Dadurch gelang es, die elektronische Struktur dieses stark gebogenen ersten ansa‐Cycloheptatrienyl‐Cyclopentadienyl‐Übergangsmetallkomplexes zu untersuchen. Der Komplex wurde aus [(η‐C7H7)Ti(η‐C5H5)] erhalten.

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Coordinatively unsaturated molybdenum complexes with chelating cycloheptatrienyl-phosphane ligands and their use in transition metal catalysis

Cited by 19 publications

References 22 publications

Chelate Complexes of Functionalized Cycloheptatrienyl Ligands: Molybdenum Complexes with Linked Cycloheptatrienyl‐Phosphane Ligands and Their Use in Catalytic Carbon−Carbon Bond Formation

Chelate Complexes of Functionalized Cycloheptatrienyl Ligands: Molybdenum Complexes with Linked Cycloheptatrienyl‐Phosphane Ligands and Their Use in Catalytic Carbon−Carbon Bond Formation

Synthesis and Reactivity of 16-Electron Cycloheptatrienyl-Molybdenum(0) Complexes with Bis(imidazolin-2-imine) Ligands

Ansa‐Cycloheptatrienyl–Cyclopentadienyl Complexes

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