Year of Publication

2006

Document Type

Dissertation

College

Arts and Sciences

Department

Chemistry

First Advisor

David A. Atwood

Abstract

A series of mononuclear boron halides of the type LBX2 (LH = N-phenyl-3,5-di-tbutylsalicylaldimine,X = Cl (2), Br (3)) and LBX ( LH2 = N-(2-hydroxyphenyl)-3,5-di-tbutylsalicylaldimine,X = Cl (7), Br (8); LH2 = N-(2-hydroxyethyl)-3,5-di-tbutylsalicylaldimine,X = Cl (9), Br (10); LH2= N-(3-hydroxypropyl)-3,5-di-tbutylsalicylaldimine,X = Cl (11), Br (12)) were synthesized from their borate precursorsLB(OMe)2 (1) (LH = N-phenyl-3,5-di-t-butylsalicylaldimine ) and LB(OMe) (LH2 = N-(2-hydroxyphenyl)-3,5-di-t-butylsalicylaldimine (4), N-(2-hydroxyethyl)-3,5-di-tbutylsalicylaldimine(5), N-(3-hydroxypropyl)-3,5-di-t-butylsalicylaldimine (6)). Theborate precursors, 1, 4 - 6, in turn, were prepared by refluxing the corresponding ligandsLH or LH2 with excess B(OMe)3. The boron halide compounds were air- and moisturesensitiveand compound 7 on hydrolysis gave the oxo-bridged compound 13 thatcontained two seven-membered boron heterocycles. The boron halide compoundsdealkylated trimethyl phosphate in stoichiometric reactions to produce methyl halide andunidentified phosphate materials. Compounds 8 and 12 were found to be the mosteffective dealkylating agents. Compound 8 on reaction with t-butyl diphenyl phosphinateproduced a unique boron phosphinate compound LB(O)OPPh2 (14) containing a terminalphosphinate group. Compounds 1-14 were characterized by 1H, 13C, 11B, 31P NMR, IR,MS, EA and MP. Compounds 5, 6, 11, 12 and 13 were also characterized by singlecrystalX-ray diffraction.The alkane elimination reaction between Salen(tBu)H2 ligands and diethylaluminumbromide was used to prepare the four Salen aluminum bromide compounds,salen(tBu)AlBr (15) (salen = N,N'-ethylenebis(3,5-di-tert-butylsalicylideneimine)),salpen(tBu)AlBr (16) (salpen = N,N'-propylenebis(3,5-di-tert-butylsalicylideneimine)),salben(tBu)AlBr (17) (salben = N,N'-butylenebis(3,5-di-tert-butylsalicylideneimine)) andsalophen(tBu)AlBr (18) (salophen = N,N'-o-phenylenenebis(3,5-di-tertbutylsalicylideneimine)).The compounds contained five-coordinate aluminum either in adistorted square planar or a trigonal bipyramidal environment. The bromide group inthese compounds could be displaced by triphenylphosphine oxide or triphenyl phosphateto produce the six-coordinate cationic aluminum compounds [salen(tBu)Al(Ph3PO)2]Br(19), [salpen(tBu)Al(Ph3PO)2]Br (20), [salophen(tBu)Al(Ph3PO)2]Br (21) and[salophen(tBu)Al{(PhO)3PO}2]Br (22). All the compounds were characterized by 1H,13C, 27Al and 31P NMR, IR, mass spectrometry and melting point. Furthermore,compounds 15, 16, 17, 18, 20, 21 and 22 were structurally characterized by single-crystalX-ray diffraction. Compounds 15, 17 and 18 dealkylated a series of organophosphates instoichiometric reaction by breaking the ester C–O bond. Also, they promoted thedealkylation reaction between trimethyl phosphate and added boron tribromide.Stoichiometric reaction of compound 15 with trimethyl phosphate produced thealuminophosphinate compound salen(tBu)AlOP(O)Ph2 (23). Compound 16 on reactionwith tributyl phosphate produced the aluminophosphate compound[salpen(tBu)AlO]2[(BuO)2PO]2 (24). Compounds 23 and 24 were characterized by singlecrystalX-ray diffraction and spectroscopically.

Share

COinS