123170-73-0Relevant articles and documents
Synthesis and chemistry of chelating phosphinite complexes of group 6 metal carbonyls with crown ether and aza-crown ether characteristics. The effect of preferential lithium cation binding by the product molecule on the reactivity of coordinated carbon monoxide
Powell, John,Gregg, Michael R.,Kuksis, Anda,May, Christopher J.,Smith, Stuart J.
, p. 2918 - 2932 (2008/10/08)
Twenty-seven α,ω-bis(diphenylphosphinite) ligands, prepared from the reaction of 2 equiv of Ph2PCl with the appropriate α,ω-diol in the presence of Et3N, react with M(CO)4(norbornadiene) (M = Cr, Mo, W) under high dilution conditions to give metalla-crown and metalla-aza-crown ether tetracarbonyl complexes. Within the series of complexes cis-Mo(CO)4{Ph2POCH2(CH2OCH 2)nCH2OPPh2} the 16C5 (n = 3) system will complex Li+ but not Na+ and the 19C6 (n = 4) system will complex Li+ and Na+ but not K+, while the IOCS (n = 1) and 13C4 (n = 2) systems do not readily complex Li+. Addition of MeLi and PhLi to these group 6 metal carbonyl-crown ether systems results in the formation of the isolable acylate/benzoylate complexes "fac-M(CO)3(RCOLi)P2]" for 11C3, 12C3, 13C4, and 14C4 ring systems while other ring sizes and complexes such as cis-Mo(CO)4{Ph2PO(CH2)nOPPh 2} (n = 3, 5) and cis-Mo(CO)4-(PPh2OMe)2 do not react with RLi reagents. Equilibrium studies of the reaction "M(CO)4P2 + RLi ? M(CO)3(RCOLi)P2" indicate that the features favoring Li+ binding and product stabilization are (i) a ligand should be one donor atom short of providing Li+ with a "full" coordination sphere, (ii) 12-14 atom metalla-crown ether rings, (iii) the ligand must accommodate the stereochemical requirements of the bridging M(RC=O)→Li+ unit, and (iv) the crown ether donor atoms should be as basic as possible {tertiary N > O, and Ph2P-O >>> Ph2P-NMe}. Kinetic studies of the rate of the reaction of "[M(CO)3(PhCOLi)P2]" systems with H2O in THF, to give "M(CO)4P2", LiOH, and benzene, provide information (kd data) regarding the relative rate of Li+ decomplexation. 12C3 benzoylate complexes and Mo(CO)5(PhCOLi) react with H2O in THF to give the starting carbonyl complex, LiOH, and benzene by a process that is first order in both [benzoylate complex] and [H2O], while the reaction of 13C4 and 14C4 benzoylates with H2O in THF gives rise to a rate law that is first order in [benzoylate] and second order in [H2O]. Equilibrium constant data and the ka data indicate that 13C4 and 14C4 benzoylates are the most stable. The complexes fac-M(CO)3(RCOLi){Ph2POCH2(CH 2OCH2)2CH2OPPh2} (i) react with Me3O+BF4 or MeSO3F to give the carbene complexes fac-M(CO)3{C(OMe)R}{Ph2POCH2(CH 2OCH2)2CH2OPPh2}, (ii) react with Me3SiCl followed by H2O/MeOH hydrolysis to give the hydroxycarbene fac-M(CO)3{C(OH)R}{Ph2POCH2-(CH 2OCH2)2CH2OPPh2}, and (iii) react with HX to give [M(CO)3X{Ph2POCH2(CH2OCH 2)2CH2OPPh2}]-Li + (X = Cl, Br). This latter compound reacts with silver salts in the presence of added ligand to give fac-M(CO)3L{Ph2POCH2(CH2OCH 2)2CH2OPPh2} (e.g. L = P(OMe)3, tBuNC).
