Heidi E. Engelhardt

Reactions of Cp2M(PMe3)2 complexes (M = Ti, Zr) with acetylenes. Selective formation of trans-polyacetylene at low temperatures

Abstract The reaction of Cp2Ti(PMe3)2 with C2H2 gives the substitution product Cp2Ti(C2H2)(PMe3), the titanacyclopentadiene Cp2Ti(C4H4), and trans-polyacetylene. A mechanism for the catalytic formation of polyacetylene is proposed. Substituted acetylens R1C2R2 (R1 ≠ R2 = H, Me, Ph) react with Cp2Ti(PMe3)2 in an analogous manner except that no polyalkynes are produced. The Zr derivative Cp2Zr(PMe3)2 and C2H2 yield the labile Cp2Zr(C2H2) (PMe3).

Darstellung und charakterisierung von metallacyclischen alkenylketonkomplexen des chroms, molybdäns und wolframs. Molekülstruktur von C5Me5(CO)2W[MeCCMeC(O)Me]

Abstract The photoinduced reaction of η5-ArM(CO)3R complexes (η-Ar = C5H5, C5H4Me, C5Me5, C9H7; M = Cr,Mo,W; R = Me, Et, nPr, nBu) with symmetrical and asymmetrical alkynes, R1CCR2 (R1, R2 = H, Me, Ph), in solution yields metallacyclic alkenylketone complexes of the type η5-Ar(CO)2 M[R 1 CR 2 C(O )R]. Spectroscopic characterization of these 1:1 adducts and the X-ray structure of C5Me5(CO)2 W[MeCCMeC(O )Me] indicate considerable double bond character for the Cα-metal bond and facile oxygen-metal dissociation.

Acetylenliganden als Bausteine für Carben- und Nitrilliganden. Molekülstrukturen von C5H4Me(CO)2Mn[C(Me)NH2], C5Me5(CO)2Mn[C(Me)NH2], C5Me5(CO)2Mn[C(Me)NMe2] und C5Me5(CO)2MnNCMe

Abstract The acetylene complexes Cp′(CO) 2 MnC 2 H 2 (Cp′ = η 5 -C 5 H 5 , η 5 -C 5 H 4 Me, η 5 -C 5 Me 5 ) react with ammonia, primary, or secondary amines such as methylamine or dimethylamine to give aminocarbene complexes of the type Cp′(CO) 2 Mn[C(Me)NR 1 R 2 ] (R 1 , R 2 = H, Me). With tertiary amines such as triethylamine, C 5 H 4 Me(CO) 2 MnC 2 H 2 is transformed into the binuclear vinylidene bridged complex [C 5 H 4 Me(CO) 2 Mn] 2 -μ-CCH 2 . Hydrazine, N 2 H 4 , and phenylhydrazine, N 2 H 3 Ph, react analogous to that of the amines, NHR 1 R 2 . The resulting complexes Cp′(CO) 2 Mn[C(Me)N 2 H 3 ] and Cp′(CO) 2 Mn[C(Me)N 2 H 2 Ph], however, readily lose NH 3 or NH 2 Ph to give the acetonitrile complexes Cp′(CO) 2 MnNCMe. The X-ray structures of the aminocarbene complexes C 5 H 4 Me(CO) 2 Mn[C(Me)NH 2 ] (IIa′), C 5 Me 5 (CO) 2 Mn[C(Me)NH 2 ] (IIa″), C 5 Me 5 (CO) 2 Mn[C(Me)NMe 2 ] (IIc″) and of the acetonitrile complex C 5 Me 5 (CO) 2 MnNCMe (IV″) are presented and compared with structures of similar complexes.

Die photoinduzierte umsetzung der tricarbonyl-hydridkomplexe Cp′W(CO)3H (Cp′ = η5-C5H5, η5-C5Me5) mit methylacetylen und dimethhylacetylen zu η3-allyl- und metallacyclischen alkenylketon-komplexen. Molekülstruktur von C5Me5W(CO)2(η3-C3H5)

The photo-induced reaction of the hydrido complexes Cp′W(CO)3H (Cp′ = η5-C5H5, η5-C5Me5) with methylacetylene and dimethylacetylene gives the η3-allyl complexes Cp′W(CO)2(η3-C3H5) and Cp′W(CO)2(η3-C4H7) and the metallacyclic alkenylketone complex C5Me5 W(CO)2[MeCCHC(O) CHCHMe]. Phenylacetylene and C5Me5W(CO)3H react in tetrahydrofuran solution under photochemical conditions to give the substitution product C5Me5W(CO)2(thf)H. The crystal structure of the complex C5Me5W(CO)2(η3-C3H5) is described.

Trimethylphosphan- und Carbonyl-hydrid-Halbsandwichkomplexe des Chroms, Molybdäns und Wolframs: C5Hf5−, C5Me5− und ein isoelektronischer 6e−-Sauerstof-Tripodligand im Vergleich

Abstract Tricarbonylhydrido complexes of the type LM(CO) 3 H (L −  η 5 -C 5 H 5 − , η 5 -C 5 Me 5 − , [C 5 H 5 Co{;P(O)(OEt) 2 }; 3 ] − ; M  Cr, Mo, W) react thermally or photochemically with PMe 3 in solution to form the monosubstitution products LM(CO) 2 (PMe 3 )H, and the disubstitution products LM(CO)(PMe 3 ) 2 H. The C 5 H 5 derivatives (R  H, Me) of the monosubstitution products consists of cis and trans isomers. The tripod analogs, however, give only the more stable cis isomer. In all cases, the disubstitution products showed only one isomer, probably the trans form. The energy barrier for the pseudo-rotation of the carbonyl and hydrido ligands in the starting materials and the substitution products is higher for the C 5 R 5 derivatives than for the compounds with O 3 -tripod ligands. The dinuclear complexes L(CO)(PMe 3 ) 2 MM(CO) 3 L could be detected as by-products from photoinduced reactions.

Synthese und Charakterisierung neuer Acetylenkomplexe des Mangans und Rheniums

Abstract The reaction of the photochemically-generated tetrahydrofuran complexes Cp′(CO) 2 M(thf) (Cp′  η 5 -C 5 H 5 , η 5 -C 5 H 4 Me, η 5 -C 5 Me 5 ; M  Mn, Re) with various alkynes R 1 C 2 R 2 (R 1 , R 2  H, Me, Ph) yields are acetylene complexes Cp′(CO) 2 MR 1 C 2 R 2 . These compounds were identified from their IR, 1 H NMR, 13 C NMR and mas spectra.

Die Konkurrenz elektronischer und sterischer Substituenteneinflüsse in metallacyclischen Pentamethylcyclopentadienyl-Alkenylketon-Komplexen des Chroms, Molydäns und Wolframs. Molekülstruktur von C5Me5(CO)2Cr[HCCPhC(O)Me]

The photoinduced reaction of the methyl complexes C5Me5M(CO)3Me (M  Cr, Mo, W) with phenylacetylene, PHC2H, yields metallacyclic alkenylketone complexes C5Me5(CO)2M[HCCPhC(O)Me] (M  Cr, Mo) and the isomeric derivatives C5Me5(CO)2M[PhCCHC(O)Mel] (M  Mo, W). The bulky C5Me5 ligand and the metal atom radius determine whether the phenyl substituent favours the electronically attractive but sterically unattractive α-position or the electronically less favourable but sterically unhindered β-position of the metallacycle. The molecular structure of C5Me5(CO)2Cr[HCCPhC(O)Me] is presented and compared with that of C5Me5(CO)2W[MeCCMeC(O)Me].

Die addition von Phosphanen an Acetylenliganden. Synthese und Charakterisierung der ylidischen Carbenkomplexe Cp′(CO)2 Mn(HCCHPR3) und der ylidischen Vinilidenkomplexe Cp′(CO)2Mn[C(PR)3CH2] (Cp′ = η5-C5H5, η5-C5H4Me, η5-C5Me5; R = Me, Et)

Abstract The acetylene complexes Cp′(CO) 2 MnC 2 H 2 (I) (Cp′ = η 5 -C 5 H 5 , η 5 -C 5 H 4 Me, η 5 -C 5 Me 5 ) react with the tertiary phosphines PR 3 (R = Me, Et) to give the 1:1 adducts Cp′(CO) 2 Mn(HCCHPR 3 ) (II) and Cp′(CO) 2 Mn[C(PR 3 )CH 2 ] (III). The reaction of I with PEt 3 favours the formation of the ylidic carbene complexes II which in turn are precursors of the ylidic vinylidene complexes III. Products II and III were identified from their IR, 1 H NMR, 13 C NMR, 31 P NMR and mass spectra.

Ungewöhnliche reaktionen der acetylenkomplexe Cp′ (CO)2MC2H2(Cp′ = η5-C5H5, η5-C5H4Me, η5-C5Me5; M = Mn, Re) mit Br2, HCl, CF3COOH und CINO

Abstract The acetylene complexes Cp′(CO) 2 MC 2 H 2 (Cp′ = η 5 -C 5 H 5 , η 5 -C 5 H 4 Me, η 5 -C 5 Me 5 ; M = Mn, Re) undergo 1:1 addition reactions with Br 2 , HCl and CF 3 COOH to give π-olefin complexes Cp′(CO) 2 Mn( trans -BrHCCHBr) and Cp′(CO) 2 -Mn(XHCCH 2 ) (X = Cl, CF 3 COO), and the η 1 -vinyl complex C 5 Me 5 (CO) 2 -(Br)Re(HCCHBr). C 5 Me 5 (CO) 2 MnC 2 H 2 and CINO give the vinyl complex C 5 Me 5 (CO)(NO)Mn(η 1 -HCCHCl). All products were identified from their IR, NMR and mass spectra.

Reaktionen der Bis(μ-hydrid-cyclopentadienyl-dicarbonyl-wolfram)-Komplexe [C5R5W(CO)2(μ-H)]2 (R=H, Me) mit SOCl2, Br2, I2, HCl, CF3COOH, PMe3, NO, ClNO und CS2

Abstract Depending on the substituent R, the bis(μ-hydridocyclopentadienyldicarbonyltungsten) complexes [C 5 R 5 W(CO) 2 (μ-H)] 2 [R = H ( 1a ), Me ( 1b )] react in different ways with a variety of substrates. In all the cases investigated the two bridging hydrido ligands are eliminated; but the reaction products are different from those products derived from analogous reactions with the complexes [C 5 R 5 M(CO) 2 ] 2 (M = Mo, W). 1a and 1b form the complexes [C 5 R 5 W(CO) 2 X 2 ] 2 (X = Cl, Br, I) with SOCl 2 and the halogens Br 2 and I 2 . Reaction of 1a with HCl gives C 5 H 5 W(CO) 3 Cl as well as a blue carbonyl-free product, probably [C 5 H 5 WCl 2 ] 2 . CF 3 COOH dehydrogenates 1b to give [C 5 Me 5 W(CO) 2 ] 2 . Reaction of PMe 3 with 1a affords the symmetrically substituted, dinuclear complex [C 5 H 5 W(CO) 2 PMe 3 ] 2 and the monomeric C 5 H 5 W(CO) 2 (PMe 3 )H. Reaction of NO with 1a,b gives the mononuclear complexes C 5 R 5 W(CO) 2 NO as well as the dinuclear (C 5 Me 5 ) 2 W 2 (CO) 3 (NO) 2 , and reaction of CS 2 with 1b gives the asymmetric dinuclear complex [C 5 Me 5 W(CO) 2 ] 2 CS 2 .