[WBr2(CO)4]2 reacts with dienes L1 [cycloocta-1,5-diene (L2), cyclooctatetraene (L3), norbornadiene (L4)] to give coordinatively unsatd. WBr2(CO)2L1 (I). I react with Lewis bases L [CNCMe3, PMe2Ph, P(OMe)3] in 1:1 molar ratio to give coordinatively unsatd. WBr2(CO)LL1 via intermediate adducts WBr2(CO)2LL1, isolated for L1 = L4. With a 3:1 molar ratio of ligand to metal, displacement of L2 or L3 occurs to give WBr2(CO)2L3 (II), whereas a 4:1 molar ratio (L = CNCMe3) gives WBr2(CO)L4. In contrast, I (L1 = L4) forms WBr2(CO)L2L4 [L = P(OMe)3, PMe2Ph; L2 = 2,2'-bipyridyl]. 1H and 31P NMR studies of II [L = P(OMe)3, PMe2Ph] reveal the presence of 2 isomers which exhibit dynamic stereochem. at ambient temp.; the static form of 1 isomer was detected at lower temps.
Coordinatively unsaturated diene complexes of tungsten(II) and their reactions with nucleophiles to give six- and seven-coordinate derivatives
VASAPOLLO, Giuseppe
1985-01-01
Abstract
[WBr2(CO)4]2 reacts with dienes L1 [cycloocta-1,5-diene (L2), cyclooctatetraene (L3), norbornadiene (L4)] to give coordinatively unsatd. WBr2(CO)2L1 (I). I react with Lewis bases L [CNCMe3, PMe2Ph, P(OMe)3] in 1:1 molar ratio to give coordinatively unsatd. WBr2(CO)LL1 via intermediate adducts WBr2(CO)2LL1, isolated for L1 = L4. With a 3:1 molar ratio of ligand to metal, displacement of L2 or L3 occurs to give WBr2(CO)2L3 (II), whereas a 4:1 molar ratio (L = CNCMe3) gives WBr2(CO)L4. In contrast, I (L1 = L4) forms WBr2(CO)L2L4 [L = P(OMe)3, PMe2Ph; L2 = 2,2'-bipyridyl]. 1H and 31P NMR studies of II [L = P(OMe)3, PMe2Ph] reveal the presence of 2 isomers which exhibit dynamic stereochem. at ambient temp.; the static form of 1 isomer was detected at lower temps.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
