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'Cobalt Diolefin Complexes' in keywords Facet   Publication Year 1988  [X]
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1988[X]
1Author    Hans-Friedrich Klein, Michael Helwig, Udo Koch, Goetz Lull, Marko Tadic, Carl Kriiger, Peter HofmannRequires cookie*
 Title    Diolefinbis(trimethyIphosphine)cobalt(0) Compounds: Stable Organometallic Radicals with Distorted Ground State Structures  
 Abstract    Diolefincobalt(O) complexes Co(L,)(PMe 3), {L, -[CH, = CHSi(0Me),],0 (1), [CH 2 =CHSi(0Et) 2 ] 2 0 (2), (CH 2 =CHCH 2) 2 SiMe 2 (3), [(CH 2 =CHCH 2) 2 N] 2 CH 2 (4)} have been synthesized from Co(C 5 H 8)(PMe 3) 3 and diolefins at ambient temperatures. Reactions with allyl ethers or with allyltin or allylphosphorus compounds involve transfer of allyl groups to the cobalt, while allylamine simply replaces cyclopentene (C S H S) to give Co(CH 2 =CHCH 2 NH 2)(PMe 3) 3 (5). Cationic cobalt(I) complexes containing olefin ligands as in 1—4 could not be obtained under conditions where norbornadiene readily gave [Co(C 7 H 8)(PMe 3) 3 ]BF 4 (6). Paramagnetic 4 shows a magnetic moment /^ eff = 2.0 /u B (between 3.6 and 293 K), corresponding to one unpaired electron per cobalt atom. Compound 4 crystallizes in the space group P2,/c with Z = 4, a = 14.986(4), b = 17.223(5), c = 15.436(3) k,ß = 117.98(2)°, V = 3518.4 Ä 3 . Each cobalt atom is ^-coordinated to a diolefin involving the smaller of two possible chelating rings. The Co—C distances range only from 2.029(6) to 2.058(6) A for the olefin ligands, whereas Co—P bond lengths at each cobalt differ significantly: Col-Pl 2.188(2), Col-P2 2.248(2); Co2-P3 2.185(2), Co2-P4 2.258(2) A. This feature of two significantly different Co-L bond lengths is hitherto seen in all structurally characterized (bisolefin)CoL 2 complexes (L = PMe,, CH 3 CN) and can be rationalized by molecular orbital calculations (Extended Hückel) on the 17 electron model system (PH 3) 2 Co(C 2 H 4) 2 . 
  Reference    Z. Naturforsch. 43b, 1427—1438 (1988); received July 1 1988 
  Published    1988 
  Keywords    Cobalt Diolefin Complexes, Synthesis, Structure, Theory 
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 TEI-XML for    default:Reihe_B/43/ZNB-1988-43b-1427.pdf 
 Identifier    ZNB-1988-43b-1427 
 Volume    43