UVM Theses and Dissertations
Format:
Print
Author:
Maddox, Annalese Felmly
Dept./Program:
Chemistry
Year:
2011
Degree:
MS
Abstract:
This theses expands on the wide range of reactivities previously observed for the triamidoamine-supported zirconium complex, [k⁵-N, N, N, N, C-(Me₃SiNCH₂2CH₂)₂Zr, (1), by focusing on the reactivity involving zirconium-amido and -arsenido based complexes. This reactivity involves the dehydrocoupling of amine-boranes via the formation of a triamidoamine-supported zirconium-amido complex as well as the distinctive insertion chemistry of triamidoamine-supported zirconium-amido and -arsenido complexes, (N₃N)ZrERR' (E =N, As; N₃N = (Me₃SiNCH₂CH₂)₃N). These complexes form guanidinate-ligated zirconium complexes and zirconium-supported arsaalkenes respectively. The solution state of several of these complexes is supported y X-ray crystallography.
Complex 1 was reacted with amine-boranes, and the dehydrocoupling activity observed. Complex 1 was used to prepare a variety of amido and iminato complexes (N₃N)ZrNRR' (4-7) using the appropriate amine in the same manner as (N₃N)ZrPHPh (2). Borane-protected zirconium-amido complexes were observed as intermediates. A successful synthesis of (N₃N)ZrNH₂ (9) was devised using NH₃BH₃.
Because small molecules have been shown to insert into Zr-P and Zr-As bonds, (N₃N)ZrNH'Bu (4), (N₃N)ZrNHPh (5), and (N₃N)ZrCl (14) were reacted with N, N'dialkylcarbodiimides to afford the new C-N bonds. The reactivity of 4,5, and 14 differs from that previously observed for other (N₃N)ZrER₂ complexes (E = P, As). The carbodiimides insert stoichiometrically into the triamidoamine ligand to form [k⁶-N, N, N, N, N, N-N(CH₂CH₂NSiMe₃)₂(CH₂CH₂NC(NR'SiMe₃)(NR'))]ZrR guanidinateligated zirconium complexes in good yields.
New C-As and C=As bonds were fonned by the reaction of small molecules with zirconium-arsenido complexes building on prior observations in the Wateman group. Alkyl-and aryl-isocyanides (R = Bn, tBu, Mes) were reacted with (N₃)ZrAsHMes (19) and (N₃N)ZrAsHPh (22) to form the meta-stable 1,1-insertion products. This intermediate was observed for several of the complexes. These complexes thermally rearrange to form zirconium-supported arsaalkenes of the form (N₃N)ZrN(R')C(H)=AsR (21 and 24). A variety of arsenido complexes and isocyanides have been observed to undergo this reactivity and the route appears to be general in nature for aryl arsenido complexes to afford the As=C product. The 1,1-insertion product, (N₃N)ZrC(AsPh₂)=NR (20), observed as an intermediate of these reactions was isolated by the reaction of (N₃N)ZrAsPh₂ (18) with the same alkyl-and aryl-isocayanides.
Complex 1 was reacted with amine-boranes, and the dehydrocoupling activity observed. Complex 1 was used to prepare a variety of amido and iminato complexes (N₃N)ZrNRR' (4-7) using the appropriate amine in the same manner as (N₃N)ZrPHPh (2). Borane-protected zirconium-amido complexes were observed as intermediates. A successful synthesis of (N₃N)ZrNH₂ (9) was devised using NH₃BH₃.
Because small molecules have been shown to insert into Zr-P and Zr-As bonds, (N₃N)ZrNH'Bu (4), (N₃N)ZrNHPh (5), and (N₃N)ZrCl (14) were reacted with N, N'dialkylcarbodiimides to afford the new C-N bonds. The reactivity of 4,5, and 14 differs from that previously observed for other (N₃N)ZrER₂ complexes (E = P, As). The carbodiimides insert stoichiometrically into the triamidoamine ligand to form [k⁶-N, N, N, N, N, N-N(CH₂CH₂NSiMe₃)₂(CH₂CH₂NC(NR'SiMe₃)(NR'))]ZrR guanidinateligated zirconium complexes in good yields.
New C-As and C=As bonds were fonned by the reaction of small molecules with zirconium-arsenido complexes building on prior observations in the Wateman group. Alkyl-and aryl-isocyanides (R = Bn, tBu, Mes) were reacted with (N₃)ZrAsHMes (19) and (N₃N)ZrAsHPh (22) to form the meta-stable 1,1-insertion products. This intermediate was observed for several of the complexes. These complexes thermally rearrange to form zirconium-supported arsaalkenes of the form (N₃N)ZrN(R')C(H)=AsR (21 and 24). A variety of arsenido complexes and isocyanides have been observed to undergo this reactivity and the route appears to be general in nature for aryl arsenido complexes to afford the As=C product. The 1,1-insertion product, (N₃N)ZrC(AsPh₂)=NR (20), observed as an intermediate of these reactions was isolated by the reaction of (N₃N)ZrAsPh₂ (18) with the same alkyl-and aryl-isocayanides.