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The 1,3‐Sn 2 O 2 ‐Heterocycle as a Ligand in Organometallic Compounds – Dimerization of the Inidene Species [{(CO) 5 M} 2 SnOR] – (M = Cr, W)
Author(s) -
Kircher Peter,
Huttner Gottfried,
Heinze Katja,
Zsolnai Laszlo
Publication year - 1998
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/(sici)1099-0682(199808)1998:8<1057::aid-ejic1057>3.0.co;2-9
Subject(s) - chemistry , organometallic chemistry , ligand (biochemistry) , group 2 organometallic chemistry , stereochemistry , medicinal chemistry , organic chemistry , receptor , molecule , catalysis , biochemistry
Dimerized inidene complexes [(CO) 5 M−Sn(OR)−M(CO) 5 ] 2 2– (M = Cr, W; R = Et, i Pr), 1 , are obtained from [{(CO) 5 M} 2 SnCl 2 ] 2– by different routes. Dimerization occurs via alkoxy‐donor tin‐acceptor bonding by which a planar Sn 2 O 2 ring is formed. The Sn–{M(CO) 5 } bonds are made in a plane vertical to this ring such that, with the R–O groups being almost coplanar with the Sn 2 O 2 ring, the overall geometry of the compounds shows idealized D 2h symmetry. – The 119 Sn‐NMR resonances of 1 are found at rather low fields (M = Cr: δ ≈ 1400; M = W: δ ≈ 1170) indicating a low‐lying tin‐centered orbital in the LUMO range. Correspondingly EHT analyses show that the 3‐center‐4π system, which characterizes monomeric inidene species [L n M−E(X)−ML n ] n , is still prevalent in the dimeric species 1 . The low‐lying π*‐type LUMOs of 1 are the rationale for the observed 119 Sn‐NMR low‐field shifts of 1 . The dimeric compounds 1 react with 2,4‐pentanedione to form chelate compounds of the same type as those characteristically obtained from monomeric inidene complexes: [{(CO) 5 Cr} 2 SnOEt] 2 2– ( 1a ) reacts to give [{(CO) 5 Cr} 2 Sn(acac)] – ( 2 ). The experimental results are verified by X‐ray analyses in addition to the usual spectroscopic and analytical investigations.