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• 667430-40-2 [Li(bpzcp)(THF)] 
• 676-58-4 methylmagnesium chloride 

Relevant academic research and scientific papers

Hybrid scorpionate/cyclopentadienyl magnesium and zinc complexes: Synthesis, coordination chemistry, and ring-opening polymerization studies on cyclic esters

The reaction of the hybrid scorplonate/cyclopentadlenyl lithium salt [Li(bpzcp)(THF)] [bpzcp = 2,2-bis(3,5-dimethylpyrazol-1 -yl)-1,1- dlphenylethylcyclopentadlenyl] with 1 equiv of RMgCI proceeds cleanly to give very high yields of the corresponding monoalkyl k2-NNn 5-C5H4 magnesium complexes [Mg(R)(k 2n5-bpzcp)] (R = Me 1, Et 2, nBu 3, tBu 4, CH2SiMe3 5, CH2Ph 6). Hydrolysis of the hybrid lithium salt [Li(bpzcp)(THF)] with NH 4CI/H2O in ether cleanly affords the two previously described regiolsomers: (bpzcpH) 1-[2,2-bis(3,5-dimethylpyrazol-1-yl)-1,1- diphenylethyl]-1,3-cyclopentadlene (a) and 2-[2,2-bis(3,5-dlmethylpyrazol-1-yl)- 1,1-dlphenylethyl]-1,3-cyclopentadlene (b). Subsequent reaction of the bpzcpH hybrid ligand with ZnR2 quantitatively yields the monoalkyl k 2-NN-n1(π)-C5H4 zinc complexes [Zn(R){k2n1(π)-bpzcp}] (R = Me 7, Et 8, 'Bu 9, CH 2SiMe310). Additionally, magnesium alkyls 1, 2, 4, and 5 can act as excellent cyclopentadlenyl and alkyl transfers to the zinc metal center and yield zinc alkyls 7-10 in good yields. The single-crystal X-ray structures of the derivatives 4,5,7, and 10 confirm a 4-coordlnative structure with the metal center in a distorted tetrahedral geometry. Interestingly, whereas alkyl magnesium derivatives 4 and 5 present a n5 coordination mode for the cyclopentadlenyl fragment, zinc derivatives 7 and 10 feature a peripheral n1(π) arrangement in the solid state. Furthermore, the reaction of the hybrid lithium salt [Li(bpzcp)(THF)] with 1 equiv of ZnCI 2 in tetrahydroturan (THF) affords very high yields of the chloride complex [ZnCI{k2 -n1 (π)-bpzcp}] (11). Compound 11 was used as a convenient starting material for the synthesis of the aromatic amide zinc compound [Zn(NH-4-MeC6H4){k2-n 1(π)-bpzcp}] (12), by reaction with the corresponding aromatic primary amide lithium salt. Alternatively, aliphatic amide and alkoxide derivatives were only accessible by protonolysls of the bis(amide) complexes [M{N(SiMe3)2}2] (M = Mg, Zn) and the mixed ligand complex [EtZnOAr)] with the hybrid ligand bpzcpH to afford [Zn(R){k 2-n1)-bpzcp}] (R = N(SiMe3)213, R = 2,4,6Me3C6H2O14) and [Mg{N(SiMe 3)2}(k2-n5bpzcp)] (15). Finally, alkyl and alkoxide-containlng complexes 1 -10 and 14 can act as highly effective single-component living initiators for the ring-opening polymerization of ε-caprolactone and lactldes over a wide range of temperatures. ε-Caprolactone is polymerized within minutes to give high molecular weight polymers with medium-broad polydlspersitles (Mn > 105, Mw/Mn = 1.45). Lactide afforded poly(lactide) materials with medium molecular weights and polydilspersitles as narrow as M w/Mn = 1.02. Additionally, polymerization of L-lactide occurred without racemlzation in the propagation process and offered highly crystalline, isotactlc poly(L-lactldes) with very high melting temperatures (Tm = 165 °C). Microstructural analysis of poly(rac-lactide) by1H NMR spectroscopy revealed that propagations occur without appreciable levels of stereoselectivity. Polymer end group analysis showed that the polymerization process is initiated by alkyl transfer to the monomer.