Wolfgang Malisch

Synthese und reaktivität von silicium-übergansmetallkomplexen : IX. Disilanylsubstituierte metallkomplexe

Abstract Reactions of [π-C 5 H 5 (CO) 3 M]Na (M = Cr, Mo, W) or [π-C 5 H 5 (CO) 2 Fe]Na with the halodisilanes (CH 3 ) 5 Si 2 X or (CH 3 ) 4 Si 2 X 2 (X = Cl, Br) yield disilanyl complexes of the type L n MSi 2 (CH 3 ) 5 or L n MSi 2 (CH 3 ) 4 X. AgBF 4 converts the chlorodisilanyl complexes into fluorinated derivatives (X = F). The chemical and spectroscopic properties of the new complexes are reported and compared with those of the corresponding monosilylated species. The interaction of pentamethyldisilanyl complexes with ylides results in a metal→carbanion transfer of the SiSi group through metal—silicon bond cleavage and transylidation. In the case of halodisilanyl compounds cleavage and transylidation is observed involving both the silicon—metal and silicon—halogen bond. These processes often occur simultaneously, but may also be verified in single steps.

Catalytic oxidations by peroxy, peroxo and oxo metal complexes: an interdisciplinary account with a personal view

Abstract In this account, we present a brief overview of our interdisciplinary efforts on the metal-assisted selective oxyfunctionalization of organic substrates in the ‘Sonderforschungsbereich (SFB 347): Selektive Reaktionen Metall-aktivierter Molekule’. The reactivity and selectivity of peroxy-, peroxo-, and oxo-type metal oxidants have been studied to gain insight into the mechanism of the oxygen transfer by such catalytic oxidants. Based on our mechanistic work, effective catalytic oxyfunctionalization methods have been developed by employing Ti, V, Re, Mn or Cr complexes as catalysts for the chemo-, regio-, diastereo- and enantioselective synthesis of hydroxy epoxides (from olefins), sulfoxides (from sulfides), and silanols (from silanes). We show that the stoichiometric dimethyldioxirane (DMD) oxidation of ligands in selected transition-metal complexes provides an useful tool for the synthesis of oxyfunctionalized compounds.

Übergangsmetall-substituierte vb elementsysteme : VIII. Darstellung und komplexchemisches verhalten von cyclopentadienyl(tricarbonyl)viametall-dimethylstibinen☆

Abstract Starting with the cyclopentadienyl(carbonyl)metal anions [π-C 5 H 5 (CO) 3 M] − (M = Cr, Mo, W) and (CH 3 ) 2 SbBr, transition metal-substituted stibines of the form π-C 5 H 5 (CO) 3 MSb(CH 3 ) 2 are obtained. The nucleophilic character of the VB element primarily determines the reactivity of these species, and shows itself in alkyl halide quarternization (a) or ligand exchange on activated metal carbonyl complexes (b). (a) yields the trialkylstibine-substituted metal cations [π-C 5 H 5 -(CO) 3 MSb(CH 3 ) 2 R]X (R = CH 3 , CH 2 CH=CH 2 , CH 2 C 6 H 5 ; X = Br, J), (b) leads to the formation of the metal carbonyl derivatives LM(CO) 5 , L 2 M(CO) 4 (M = Cr, Mo, W), LNi(CO) 3 and LFe(CO) 4 [L = (CH 3 ) 2 SbM(CO) 3 -π-C 5 H 5 ] which are the first (CH 3 ) 2 Sb-bridged polynuclear complexes. Phosphorus ylides cause heterolytic cleavage of the antimonytransition metal bond. Transfer of the (CH 3 ) 2 Sb-group to the ylidic carbanion occurs via substitution/transylidation. All new compounds have been fully characterized by means of 1 H NMR, IR and mass spectroscopy

Hydrophosphination with cationic primary phosphine iron complexes: synthesis of P-chiral functionalized phosphines

Abstract The synthesis of P-chiral secondary phosphines, characterized by phosphorus and side chain chirality, has been realized via insertion of various organic multiple bond systems into the PH-bond of the primary phosphine complexes {C 5 R 5 (OC) 2 Fe[P(R′)H 2 ]}BF 4 (R=H, Me; R′=alkyl, aryl). In the case of acetylenedicarboxylic acid dimethylester a double hydrophosphination is observed, leading diastereospecifically to the dinuclear complexes {C 5 R 5 (OC) 2 Fe{P(H)(R′)[C(H)(CO 2 Me)]}} 2 (BF 4 ) 2 (R=H, Me; R′= t -Bu, 2-py), bearing four stereogenic centers. The use of p -benzoquinone gives access to secondary 2,5-bis(hydroxy)aryl phosphine ligands, suitable for further derivatizations. α-Hydroxyalkyl phosphine iron complexes can be obtained by hydrophosphination of aldehydes and ketones. Transformation into highly functionalized tertiary phosphine complexes is performed by a further hydrophosphination step using the alkenes H 2 CCHX (X=CN, 2-py), diazoacetic ethylester, p -benzoquinone or ethylisocyanate, respectively, in special cases formation of functionalized azaphospholane ligands is observed. Release of the phosphines from the metal is achieved by photoinduced ligand exchange. In addition, primary phosphine iron complexes {C 5 H 5 (diphos)Fe[P(R)H 2 ]}BF 4 (diphos=DIOP, CHIRAPHOS) bearing chiral bis(phosphine) ligands have been used to provide the stereocontrol of the hydrophosphination process.

Synthese und reaktivität von silicium-übergangsmetallkomplexen. XXIX. Trihydridosilyl-komplexe von eisen und ruthenium: Ein einfacher Zugang, ligandaustauschreaktionen am metall und schwingungsspektroskopische analyse

Abstract The ferro- and ruthenio-trihydridosilanes (C5R5)(OC)2MSiH3 [R  H, M  Fe (3a), Ru (3b); R  Me, M  Fe (3c), Ru (3d)] are prepared via reaction of the ferro- and ruthenio-dichlorosilanes (C5R5(OC)2 MSiHCl2 (2a−d) with LiAlH4 in Et2O. Photo-induced substitution of CO can be achieved in the case of 3a with Me3P (4a) or Ph3P (4b), leading to the formation of the phosphane-substituted ferro-trihydridosilanes Cp(OC)(L)FeSiH3 [L  Me3P (5a), Ph3P (5b)] and Cp(Me3P)2FeSiH3 (6). The new silicon-transition metal complexes were characterized in detail spectroscopically (NMR, IR, Raman). The structure of 3c has been determined by X-ray structural analysis.

Übergangsmetall-substituierte phosphane, arsane und stibane : XXVIII. Übergangsmetall-diphenylphosphane von molybdän und wolfram; darstellung, reaktionen und NMR-spektroskopische charakterisierung

Abstract Na[M(CO) 3 Cp] (M = Mo, W) and Ph 2 PCl react to give the transition metal substituted phosphanes Cp(CO) 3 MPPh 2 (I, II), which are transformed to trans -Cp(CO) 2 PMe 3 MPPh 2 (III, IV) via CO/PMe 3 -exchange. The high nucleophilicity of the phosphanes I–IV is demonstrated by the spontaneous formation of [Cp(CO) 2 LMPPh 2 R′]Hal (L = CO,PMe 3 ; R′ = H,Me,Br) (V–VIII) with HCl, MeI, Br 2 or Cp(CO) 2 LMPPh 2 S(Se) (IX–XII) with elementary sulfur or selenium, respectively. IX and X are easily converted to Cp(CO) 2 W[η 2 -PPh 2 S(Se)] with loss of CO on thermal treatment or photolysis. The new compounds are characterized by IR spectroscopy, elementary analysis and detailed NMR spectroscopy.

Übergangsmetall-substituierte phosphane, arsane und stibane : XXIX. Metallierte arsane und stibane mit chiralem eisen-substituenten

Abstract The reaction of Cp(CO) 2 FeEMe 2 (E  As, Sb, Bi) with Me 3 P, Et 3 P, Me 2 PhP and (MeO) 3 P leads to a CO/R 3 P exchange and formation of the chiral derivatives Cp(CO)(R 3 P)FeEMe 2 . Cp(CO)[(MeO) 3 P]FeEMe 2 rearranges already at room temperature to Cp(CO)[(Me 3 E]FeP(O)(OMe) 2 which is transformed by (MeO) 3 P to Cp(CO)[(MeO) 3 P]FeP(O)(OMe) 2 . The high nucleophilicity of the new organometallic Lewis bases is established by the easy conversion of Cp(CO)(Me 3 P)FeSbMe 2 to [Cp(CO)(Me 3 P)Fe(SbMe 3 )]I with MeI, or to [Cp(CO)(Me 3 P)FeSbMe 2 Fe(CO)LCp]Hal (L  CO, Hal  Cl; L  Me 3 P, Hal  Br) with Cp(CO)LFe-Hal, respectively. The new compounds are characterized by spectroscopy and elementary analyses.

Synthese und reaktivität von silicium-übergangsmetall-komplexen: XVI. Anionische verschiebung eisen-koordinierter dialkyl-aminosilyl-liganden zur η5-cyclopentadienyl-einheit☆

Abstract The reaction of Cp(CO) 2 FeSiMe 2 Cl ( 1 ) with LiNMe 2 provides a ready access to the iron silylamine Cp(CO) 2 FeSiMe 2 NMe 2 ( 2 ). In addition the binuclear complex [η 5 -(Me 2 NSiMe 2 C 5 H 4 )(CO) 2 Fe] 2 ( 3 ) is obtained, the formation of which involves an anionic shift of the aminosilyl group from the iron atom to the η 5 -coordinated cyclopentadienyl ring. An analogous silyl migration is responsible for the conversion of 2 or Cp(CO) 2 FeSiMe 2 H ( 4 ), respectively, into η 5 -(Me 2 NSiMe 2 -C 5 H 4 )(CO) 2 FeMe ( 5 ) via successive treatment with LiNMe 2 and MeI, and of Cp(CO) 2 FeSiMe 2 Br to η 5 -(i-Pr 2 NSiMe 2 C 5 H 4 )(CO) 2 FeMe ( 7 ) with LiN-i-Pr 2 and MeI. The analogous reaction of Cp(CO) 2 FeSiMe 3 ( 8 ) with LiNMe 2 and MeI, MeSiHCl 2 , or LiN-i-Pr 2 and Me 2 SbBr, yields the neutral iron complexes η 5 -(Me 3 SiC 5 H 4 )(CO) 2 FeX (X = Me ( 9a ), X = SiMe(H)Cl ( 9b ), X = SbMe 2 ( 9c )). 9a couples with 8 under photochemical conditions to the unsymmetrical binuclear complex [C 5 H 5 (Me 3 SiC 5 H 4 )Fe 2 (CO) 4 ] ( 10 ) with elimination of Me 4 Si.

Synthesis, X-ray structures and reactivity of the first bis(amino)metallastibanes and bis(amino)metallabismuthanes

The reaction of Me2Si(N-t-Bu)2ECl (E = Sb, Bi) with NaM(CO)nCp (M = Fe, Mo, W; Cp = ?5-C5H5) affords metallastibanes and bismuthanes, Cp(CO)nME(N-t-Bu)2SiMe2 (4a-c, 5a-c). The structures of 4c (E = Sb, M = W) and 5c (E = Bi, M = W) have been determined by X-ray crystallography. Both compounds are isotypic and isostructural and crystallize in the triclinic space group with a = 7.030 (9) A°, b = 10.51 (1) A°, c = 16.22 (2) A°, a = 94.1 (1)°, s = 90.4 (1)°, ? = 104.9 (1)°, Z = 2 for 4c and a = 7.014 (9) A°, b = 10.57 (1) A°, c = 16.25 (2) A°, a = 94.1 (1)°, s= 90.1 (1)°, ? = 104.6 (1)°, Z = 2 for 5c. The E-W s-bond lengths are 3.010 (1) A° for E = Sb and 3.082 (1) A° for E = Bi. The reaction of the antimony derivatives with Fe2(CO)9 yields [Fe(CO)4]Cp(CO)nMSb(N-t-Bu)2SiMe2 (6a-c) as a result of the complexation of the antimony lone pair. The crystal structures of 6a (M = Fe) and 6b (M = Mo) have been determined. 6a crystallizes in the monoclinic space group with a = 10.399 (9) A°, b = 16.76 (2) A°, c = 15.74 (1) A°, s = 94.16 (6)°, and Z = 4. Both Sb-Fe bond lengths are almost similar: 2.547 (1) A° for the covalent bond and 2.530 (1) A° for the dative bond. 6b crystallizes in the monoclinic space group with a = 12.305 (7) A°, b = 13.812 (7) A°, c = 16.75 (1) A°, s = 99.03 (5)°, and Z = 4. The Sb-Mo covalent bond length is 2.871 (1) A° and the Sb-Fe dative bond 2.539 (1) A°.

[2+2]-Cycloaddukte PH-funktioneller Phosphenium-Komplexe mit Alkylisothiocyanaten: Darstellung von C5R5(OC)2M–P(H)(t-Bu)–C(NR′)–S (R=H, Me; M=Mo, W; R′=Me, Et, t-Bu) und Reaktion unter Beanspruchung der PH-Funktion: Phosphenium-Übergangsmetallkomplexe, 37

Abstract The phosphenium complex C5Me5(OC)2WP(H)t-Bu (2c) reacts with the alkylisothiocyanates RNCS (R=Me, Et, t-Bu) (3a–c) via [2+2]-cycloaddition to form the PH-functionalized phosphametallacycles C5Me5(OC)2 W–P(H)(t-Bu)–C(NR)–S (R=Me, Et, t-Bu) (4a–c). In the case of the Cp-substituted phosphenium complexes Cp(OC)2MP(H)t-Bu (M=Mo, W) (2a,b) additional insertion of the isothiocyanate into the PH bond occurs yielding the cycloadducts Cp(OC)2 M–P[C(S)NHR](t-Bu)–C(NR)–S (M=Mo, W; R=Me, Et, t-Bu) (5a–c) with high diastereoselectivity. The analogous C5Me5-substituted compounds C5Me5(OC)2 W–P[C(S)N(H)R](t-Bu)–C(NR)–S (R=Me, t-Bu) (5d,e) are only obtained by treatment of 2c with a large excess of 3a,c. Insertion is realized as a separate step for 4c and EtNCS (3b) leading to the formation of isomeric C5Me5(OC)2 W–P[C(S)N(H)R 1 ](t-Bu)–C(NR 2 )–S [R1=Et, R2=t-Bu (6a); R1=t-Bu, R2=Et (6b)]. The structure of 5d is characterized by X-ray diffraction analysis.