84537-77-9Relevant articles and documents
Synthesis of group 6 metalla-(aza)-crown ether tetracarbonyl complexes with potentially anionic amido groups. The influence of Li+, Mg2+, and Al3+ cations on the susceptibility of the carbonyl ligand to nucleophilic addition of alkyl/aryl carbanions and hydride
Powell, John,Gregg, Michael R.,Meindl, Patricia E.
, p. 2942 - 2947 (2008/10/08)
The reaction of Mo(CO)4(norbornadiene) with the appropriate α,ω-di-P-donor ligands, containing amido functional groups using high dilution techniques, gives cis-Mo(CO)4P2? complexes in 30-60% yields {where P2? = R2PO(CH2)3NHC(O)CH2CH(Me)OPR 2 [R2 = Ph2, complex 3; R2 = MeNCH2CH2NMe, 4], Ph2PO(CH2)2O(CH2) 2NHC(O)CH2CH(Me)OPPh2 (5), Ph2PNH(CH2)3NMe(CH2) 3NHPPh2 (6), Ph2PNHCH2(CH2OCH2) 2CH2NHPPh2 (7)}. Deprotonation of the amido NH(s) of these complexes lead to anionic 12C3, 13C4, and 14C4 metalla-aza-crown ether tetracarbonyls. Reaction of 3, 4, and 5 with PhMgCl leads to deprotonation of the amido group with no encapsulation of "Mg2+" by the resultant anionic 12C3 and 14C4 ring systems. Reaction with RLi (R = Ph, Me) leads to an equilibrium mixture of (i) the deprotonated species, (ii) a species in which the Li+ is partly encapsulated by the anionic amidate-crown ether ring (N- and 2PO coordination to Li+), and (iii) a benzoylate/acylate complex fac-Mo(CO)3(RCOLi)P2? in which the Li+ is completely encapsulated by the dianionic molybdenum complex. Addition of excess RLi forces the system to 100% benzoylate/acylate (IR monitoring, v(CO) region). Complexes 6 and 7 and the non-crown ether system cis-Mo(CO)4{Ph2PNH(CH2)5NHPPh 2} (27) react with 3 equiv of RLi to give fac-[Mo(CO)3(RCOLi)P2?]Li2 which contains one Li+ encapsulated by the trianionic complex. Reaction of these complexes with anhydrous AlBr3 leads to neutral, isolable, and chemically relatively stable compounds fac-[Mo(CO)3(RCOAl){P2?-2H+}]. The stability of these benzoylate/acylate compounds, via a? vis "M-(CO)4(PR3)2 + RLi systems" (no reaction), can be ascribed to preferential Li+ or Al3+ binding by the product molecule. The reaction of 6 with 3 equiv of LiAlH4 in THF solution resulted in the evolution of 2 equiv of H2 gas, and the formation of a "fac-Mo(CO)3" solution species tentatively formulated as the formylate [Mo(CO)3(HCOLi)P2?]Li2 on the basis of IR [v(CO)] and 13C{1H} NMR data. Similar reactions were observed when 3LiAlH4 was added to 7 and 27. In contrast the molybdenum-crown ether tetracarbonyl cis-Mo-(CO)4{Ph2POCH2(CH2OCH 2)2CH2OPPh2} does not react with LiAlH4 under similar conditions.
