Synthesis of (tBu3SiNH)2ClWWCl(NHSitBu3)2 and Its Degradation via N
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- 作者：Stephen M. Holmes ; Daniel F. Schafer II ; Peter T. Wolczanski ; and Emil B. Lobkovsky
- 刊名：Journal of the American Chemical Society
- 出版年：2001
- 出版时间：October 31, 2001
- 年：2001
- 卷：123
- 期：43
- 页码：10571 - 10583
- 全文大小：193K
- 年卷期：v.123,no.43(October 31, 2001)
- ISSN：1520-5126
文摘
Treatment of NaW2Cl7(THF)5 with 4 equiv of tBu3SiNHLi afforded the C2 W(III) dimer[(tBu3SiNH)2WCl]2 (1, d(W
W) = 2.337(2) Å), which is a rare, primary amide M2X4Y2 species. Its degradationprovided evidence of NH bond activation by the ditungsten bond. Addition of 2 equiv of tBu3SiNHLi orTlOSitBu3 to 1 yielded H2 and hydride (tBu3SiN)2(tBu3SiNH)WH (2, d(WH) = 1.67(3) Å) or (tBu3SiN)2(tBu3SiO)WH (3). Thermolysis (60 
C, 16 h) of 1 in py gave (tBu3SiN)2WHCl(py) (4-py, 40-50%), (tBu3SiN)2WCl2(py) (6-py, 10%), and (tBu3SiN)2HW(
-Cl)(-H)2W(NSitBu3)py2 (5-py2, 5%), whereas thermolysisin DME produced (tBu3SiN)2WCl(OMe) (7, 30%), (tBu3SiN)2WCl2 (6, 20%), and (tBu3SiN)2HW(-Cl)(-H)2W(NSitBu3)DME (5-DME, 3%). Compound 7 was independently produced via thermolysis of 4-py andDME (-MeOEt, -py), and THF and ethylene oxide addition to hydride 2 gave (tBu3SiN)2(tBu3SiNH)WOnBu(8) and (tBu3SiN)2(tBu3SiNH)WOEt (9), respectively. Dichloride 6 was isolated from SnCl4 treatment of 1with the loss of H2. Sequential NH bond activations by the W2 core lead to "(tBu3SiN)2WHCl" (4) and subsequentthermal degradation products. Thermolysis of 1 in the presence of H2C=CHtBu and PhCCPh trapped 4 andgenerated (tBu3SiN)2W(neoHex)Cl (10) and a ~6:1 mixture of (tBu3SiN)2WCl(cis-CPh=CPhH) (11-cis) and(tBu3SiN)2WCl(trans-CPh=CPhH) (11-trans), respectively. Thermolysis of the latter mixture afforded(tBu3SiNH)(tBu3SiN)WCl(
2-PhCCPh) (12) as the major constituent. Alkylation of 1 with MeMgBr produced(tBu3SiN)2W(CH3)2 (13), as did addition of 2 equiv of MeMgBr to 6. X-ray crystal structure determinationsof 1, 2, 5-py2, 6-py, 11-trans, and 12 confirmed spectroscopic identifications. A general mechanism that featuresa sequence of NH activations to generate 4, followed by chloride metathesis, olefin insertion, etc., explainsthe formation of all products.
W) = 2.337(2) Å), which is a rare, primary amide M2X4Y2 species. Its degradationprovided evidence of NH bond activation by the ditungsten bond. Addition of 2 equiv of tBu3SiNHLi orTlOSitBu3 to 1 yielded H2 and hydride (tBu3SiN)2(tBu3SiNH)WH (2, d(WH) = 1.67(3) Å) or (tBu3SiN)2(tBu3SiO)WH (3). Thermolysis (60 C, 16 h) of 1 in py gave (tBu3SiN)2WHCl(py) (4-py, 40-50%), (tBu3SiN)2WCl2(py) (6-py, 10%), and (tBu3SiN)2HW(-Cl)(-H)2W(NSitBu3)py2 (5-py2, 5%), whereas thermolysisin DME produced (tBu3SiN)2WCl(OMe) (7, 30%), (tBu3SiN)2WCl2 (6, 20%), and (tBu3SiN)2HW(-Cl)(-H)2W(NSitBu3)DME (5-DME, 3%). Compound 7 was independently produced via thermolysis of 4-py andDME (-MeOEt, -py), and THF and ethylene oxide addition to hydride 2 gave (tBu3SiN)2(tBu3SiNH)WOnBu(8) and (tBu3SiN)2(tBu3SiNH)WOEt (9), respectively. Dichloride 6 was isolated from SnCl4 treatment of 1with the loss of H2. Sequential NH bond activations by the W2 core lead to "(tBu3SiN)2WHCl" (4) and subsequentthermal degradation products. Thermolysis of 1 in the presence of H2C=CHtBu and PhCCPh trapped 4 andgenerated (tBu3SiN)2W(neoHex)Cl (10) and a ~6:1 mixture of (tBu3SiN)2WCl(cis-CPh=CPhH) (11-cis) and(tBu3SiN)2WCl(trans-CPh=CPhH) (11-trans), respectively. Thermolysis of the latter mixture afforded(tBu3SiNH)(tBu3SiN)WCl(2-PhCCPh) (12) as the major constituent. Alkylation of 1 with MeMgBr produced(tBu3SiN)2W(CH3)2 (13), as did addition of 2 equiv of MeMgBr to 6. X-ray crystal structure determinationsof 1, 2, 5-py2, 6-py, 11-trans, and 12 confirmed spectroscopic identifications. A general mechanism that featuresa sequence of NH activations to generate 4, followed by chloride metathesis, olefin insertion, etc., explainsthe formation of all products.