TY - JOUR
T1 - Synthesis and characterization of calcium N, N -dimethylaminodiboranates as possible chemical vapor deposition precursors
AU - Dunbar, Andrew C.
AU - Girolami, Gregory S.
PY - 2014/1/21
Y1 - 2014/1/21
N2 - The reaction of CaBr2 with 2 equiv of sodium N,N-dimethylaminodiboranate, Na(H3BNMe2BH3) in Et2O at 0 C followed by crystallization and drying in vacuum yields the unsolvated calcium compound Ca(H3BNMe2BH 3)2, 1. Before the vacuum drying step, the colorless crystals obtained by crystallization consist of the diethyl ether adduct Ca(H3BNMe2BH3)2(Et 2O)2, 2. If the reaction of CaBr2 with 2 equiv of Na(H3BNMe2BH3) is carried out in the more strongly coordinating solvent tetrahydrofuran (thf), the solvate Ca(H 3BNMe2BH3)2(thf)2, 3, is obtained. This compound does not desolvate as easily in vacuum as the diethyl ether compound 2. Treating the thf adduct 3 with 1,2-dimethoxyethane (dme), bis(2-methoxyethyl) ether (diglyme), or N,N,N′,N′- tetramethylethylenediamine (tmeda) in thf affords the new compounds Ca(H 3BNMe2BH3)2(dme), 4, Ca(H 3BNMe2BH3)2(diglyme), 5, and Ca(H3BNMe2BH3)2(tmeda), 6, respectively, in greater than 60% yields. Treatment of 3 with 2 equiv of the crown ether 12-crown-4 in thf affords the charge-separated salt [Ca(12-crown-4)2][H3BNMe2BH3] 2, 7. Crystal structures of all the Lewis base adducts are described. Compounds 2-6 all possess chelating κ2-BH3NMe 2BH3-κ2 groups, in which two hydrogen atoms on each boron center are bound to calcium. Compound 7 is the only ionic compound in the series; the Ca atom is completely encapsulated by two 12-crown-4 rings, and the anions are charge-separated counterions within the unit cell. When heated, the dme, diglyme, and tmeda compounds 4, 5, and 6 melt without decomposition, and can be sublimed readily under reduced pressure (1 Torr) at 90 C (4) and 120 C (5, 6). The dme adduct is one of the most volatile calcium compounds known, and is a promising CVD precursor for the growth of calcium-containing thin films.
AB - The reaction of CaBr2 with 2 equiv of sodium N,N-dimethylaminodiboranate, Na(H3BNMe2BH3) in Et2O at 0 C followed by crystallization and drying in vacuum yields the unsolvated calcium compound Ca(H3BNMe2BH 3)2, 1. Before the vacuum drying step, the colorless crystals obtained by crystallization consist of the diethyl ether adduct Ca(H3BNMe2BH3)2(Et 2O)2, 2. If the reaction of CaBr2 with 2 equiv of Na(H3BNMe2BH3) is carried out in the more strongly coordinating solvent tetrahydrofuran (thf), the solvate Ca(H 3BNMe2BH3)2(thf)2, 3, is obtained. This compound does not desolvate as easily in vacuum as the diethyl ether compound 2. Treating the thf adduct 3 with 1,2-dimethoxyethane (dme), bis(2-methoxyethyl) ether (diglyme), or N,N,N′,N′- tetramethylethylenediamine (tmeda) in thf affords the new compounds Ca(H 3BNMe2BH3)2(dme), 4, Ca(H 3BNMe2BH3)2(diglyme), 5, and Ca(H3BNMe2BH3)2(tmeda), 6, respectively, in greater than 60% yields. Treatment of 3 with 2 equiv of the crown ether 12-crown-4 in thf affords the charge-separated salt [Ca(12-crown-4)2][H3BNMe2BH3] 2, 7. Crystal structures of all the Lewis base adducts are described. Compounds 2-6 all possess chelating κ2-BH3NMe 2BH3-κ2 groups, in which two hydrogen atoms on each boron center are bound to calcium. Compound 7 is the only ionic compound in the series; the Ca atom is completely encapsulated by two 12-crown-4 rings, and the anions are charge-separated counterions within the unit cell. When heated, the dme, diglyme, and tmeda compounds 4, 5, and 6 melt without decomposition, and can be sublimed readily under reduced pressure (1 Torr) at 90 C (4) and 120 C (5, 6). The dme adduct is one of the most volatile calcium compounds known, and is a promising CVD precursor for the growth of calcium-containing thin films.
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U2 - 10.1021/ic402237b
DO - 10.1021/ic402237b
M3 - Article
AN - SCOPUS:84892775076
SN - 0020-1669
VL - 53
SP - 888
EP - 896
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 2
ER -