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Synthesis of Molybdenum Carbene Complexes of Thiophene Derivatives
Author(s) -
Landman Marilé,
Görls Helmar,
Lotz Simon
Publication year - 2002
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/1521-3749(200209)628:9/10<2037::aid-zaac2037>3.0.co;2-t
Subject(s) - thiophene , carbene , molybdenum , chemistry , moiety , medicinal chemistry , deprotonation , stereochemistry , catalysis , organic chemistry , ion
Dinuclear molybdenum biscarbene complexes, [M(CO) 5 C(OEt)spacerC(OEt)M(CO) 5 ], were synthesized employing the classical Fischer method. The connecting spacer unit in each case was a heterocyclic thiophene derivative and included deprotonated thiophene (HTH) 2 , 2, 2'‐bithiophene (HT‐TH) 5 , 3, 6‐dimethylthieno[3, 2‐ b ]thiophene (HT'T'H) 8 as well as dithieno[3, 2‐ b ;2', 3'‐ d ] thiophene (HTTTH) 11 . In each of the cases the particular monocarbene complex [Mo(CO) 5 C(OEt)TH]( 1 ), [Mo(CO) 5 C(OEt)T‐TH] ( 4) , [Mo(CO) 5 C(OEt)T'T'H] ( 7 ) or [Mo(CO) 5 C(OEt)TTTH] ( 10 ) was obtained as a byproduct of the reaction. The more reactive biscarbene complexes of thiophene, [Mo(CO) 5 C(OEt)TC(OEt)Mo(CO) 5 ]( 2 ), 2, 2'‐bithiophene, [Mo(CO) 5 C(OEt)T‐TC(OEt)Mo(CO) 5 ]( 5 ), and 3, 6‐dimethylthieno[3, 2‐ b ]thiophene, [Mo(CO) 5 C(OEt)T'T'C(OEt)Mo(CO) 5 ] ( 8 ), yielded, upon exposure to trace amounts of water or oxygen, modified monocarbene products, complexes [Mo(CO) 5 C(OEt)TC(O)OEt] ( 3 ), [Mo(CO) 5 C(OEt)T‐TC(O)OEt] ( 6) and [Mo(CO) 5 C(OEt)T'T'C(O)OEt] ( 9 ) respectively, in which one metal moiety was replaced by an oxygen group. In the case of the more stable dithieno[3, 2‐ b ;2', 3'‐ d ]thiophene bis carbene complex [Mo(CO) 5 C(OEt)TTTC(OEt)Mo(CO) 5 ] ( 11 ), this product was absent. Instead, a biscarbene product [Mo(CO) 5 C (OEt)TTTC(OEt)C(OEt)TTTC(OEt)Mo(CO) 5 ] ( 12 ) was yielded that contained an extended conjugated bridging ligand, resulting from a carbene‐carbene coupling reaction.