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1982 (1)
1981 (1)
1Author    Ridvan Talay, Dieter RehderRequires cookie*
 Title    Carbonylvanadium  
 Abstract    , -mangan-und -molybdänkomplexe mit den Liganden o-C6H4EPh2(E Ph2) (E, E = P, As, Sb, Bi) und cis-Ph2PCH=CHPPh2 Carbonylvanadium, -manganese and -molybdenum Complexes of the Ligands o-C6H4EPh2(E'Ph2) (E, E' = P, As, Sb, Bi) and cis-Ph2PCH=CHPPh2 The photo-induced reaction between the complexes [Et4N][V(CO)6] (1), j? 5 -C5H5V(CO)4 (2), f? 5 -C5H5Mn(CO)3 (3) or 7? 5 -C5H5Mo(CO)3CH3 (4) and the ligands o-C6H4EPh2(E'Ph2) (E = E' = P: a; E = P, E'=As: b; E = E'= As: C; E = P, E'=Sb: d; E = P, E'= Bi: e; E = As, E' = Sb: f) and ds-Ph2PCH = CHPPh2 (g), L, yields -depending on the steric requirement of L -the compounds (M}L ({M} = cw-V(CO)4-, eis-CpV(CO)2, CpMn(CO), CpMo(CO)CH3; L = a, b, c, g), {M'}L ({M'j = V(CO)5-, L -d; {M'} -CpV(CO)3, L -d, e; {M'} = CpMn(CO)2, L = e) or mixtures of {M}L and (M'}L ({M}, {M'} = V(CO)4,5, L = e,f; {M}, {M'} = CpV(CO)2>3, L = f). In the mono-substituted species {M'}L coordination (as indicated by the 51 V NMR spectra) occurs through EPh2 and E'Ph2, which is explained by a reaction path via a labile chelate 5-ring structure. Shielding of the 51 V nucleus decreases in the order g > SbPh2 > PPh2 > AsPh2 > BiPh2 (derivatives of 1) and g > SbPh2 > PPh2 > BiPh2 >AsPh2 (derivatives of 2), and is smaller in the rigid chelates incorporating the o-phenylene ligands than in the more flexible structures of phospha-and arsabutane complexes. This fact is discussed in terms of hindered <7-overlap due to distortion of the EVE angle, which also results in an increase of CO valence force constants in rigid chelates. 31 P coordination shifts increase according to dppe < a < g and arphos < b (dppe = Ph2P(CH2)2PPh2, arphos = Ph2As(CH2)2PPh2). 31 P NMR spectra of the molybdenum complexes suggest that the basic geometry for 4 a and 4 b likely is tetragonal pyramidal, while the preferred structure for 4 g appears to be the trigonal bipyramid with the ligand in equatorial positions. The crystal and molecular structure of 1 a is reported. The complex crystallizes in the space group C2/c (a = 2196.0, b= 1080.1, c = 2022.7 pm, ß= 124.6°). The most striking result is the small PVP angle of 80.8 (0.2)°. Optimized methods for the synthesis of the ligands a-f are described; the ligands are characterized by their mass spectra. 
  Reference    Z. Naturforsch. 36b, 451—462 (1981); eingegangen am 4. Dezember 1980 
  Published    1981 
  Keywords    Carbonylphosphinevanadium, Vanadium-NMR, Phosphorus-NMR 
  Similar Items    Find
 TEI-XML for    default:Reihe_B/36/ZNB-1981-36b-0451.pdf 
 Identifier    ZNB-1981-36b-0451 
 Volume    36 
2Author    Dieter Rehder, Hans-Christoph Bechthold, Ahmet Keçeci, Hartwig Schmidt, Michael SiewingRequires cookie*
 Title    A Comparative Study of Metal Shielding in Low Valent Vanadium, Niobium and Manganese Complexes  
 Abstract    Variations of the metal chemical shifts <5(51 V), <5(55 Mn) and <S(93 Nb) with the para-magnetic deshielding contribution to the overall shielding are discussed in terms of influences imposed by the ligand field splitting, the nephelauxetic effect and the covalency of the metal-to-ligand bond. Complexes under investigation are isoelectronic and/or iso-structural series [M(CO)6_nL"]<i (M = V, Nb: q = —1; M = Mn: q = + 1; n = 0-6), 7? 5 -C5H5M(CO)4-KLn (M = V, Nb; n = 0-4) and r? 5 -C5H5M(L /)2L (M = V, L' = NO; M = Mn, L' = CO). L is a monodentate or l/n oligodentate phosphine. <5 varies with the point symmetry of the complex, and with ligand parameters of primarily electronic or steric origin. Generally, for weak to medium ^-interaction, there is a decrease of shielding with decreasing yr-acceptor power of the ligand, increasing ligand bulkiness, increasing ring strains in chelate structures and increasing degree of substitution. For strong ^-inter-action, the trends may be interconverted. PF3 is shown to be a slightly weaker 7r-acceptor than CO. Selected results on nuclear-spin spin coupling constants, 13 C and 31 P shielding are also presented. 
  Reference    Z. Naturforsch. 37b, 631—645 (1982); eingegangen am 25. November 1981 
  Published    1982 
  Keywords    Carbonylphosphinevanadium, Carbonylphosphineniobium, Carbonylphosphinemanganese, NMR Spectra 
  Similar Items    Find
 TEI-XML for    default:Reihe_B/37/ZNB-1982-37b-0631.pdf 
 Identifier    ZNB-1982-37b-0631 
 Volume    37