Polarity reversal in η2-phosphinocarbene and η2-arsinocarbene complexes of tungsten
摘要:
Trichloro- and trifluoroacetic acids CF(3)COOh and CCl3COOH react with cationic eta(2)-phosphino-(Cp(CO)(PMe3)-W=C(R)-PPh2(BF4) as well as eta(2)-arsinocarbene complexes of tungsten (Cp(CO)(2)W=C(R)-AsPh2)(PF6) to form the corresponding eta(2)-phosphinomethanide (Cp(CO)(PMe3)(Y)W-C(H)(R)-PPh2)(BF4) (Y = CF3COO, CCl3COO) or eta(2)-arsinomethanide compounds (Cp(CO)(2)(CF3COO)W-C(H)(R)-AsPh2)(PF6), respectively. Next to spectroscopic investigations, the constitution of the new compounds is proved by X-ray single crystal structure determinations. (C) 1999 Elsevier Science S.A. All rights reserved.
Conversion of η2-phosphinocarbene complexes into tungstaphosphabicyclo[1.1.0]butanone units
摘要:
Cationic eta(2)-phosphinocarbene complexes [eta(2)-C5H5(CO)(PMe3)<(W = C(R)-P)over bar>Ph-2][PF6] (R = Me, Ph, Tol) react at -78 degrees C with alkyl isonitriles R'NC (R' = Me, Bu-t) to provide tungstaphosphabicyclo[1.1.0]butanone complexes [eta(5)- C5H5(R'NC)(PMe3)<(W-C(O)-C)over bar>(R)-PPh2][PF6] in high yields. The constitution of the yellow bicyclic compounds was determined by spectroscopic investigations and, in the case of the 4-methylphenyl substituted compound 2c, additionally by X-ray single crystal structure analysis. Crystal data for 2c are as follows: space group P2(1)/n (No. 14), a = 907.80(10), b = 3658.1(6), c = 1085.2(2) pm, alpha = 90 degrees, beta = 106.27(1)degrees, gamma = 90 degrees, Z = 4. (C) 1998 Elsevier Science S.A.
η2-Phosphinocarbebe complexes of tungsten show a different behaviour towards anionic nucleophiles. The cationic η2-phosphinocarbene complex reacts with the thiophenolate anion PhS− via carbonyl substitution, whereas the corresponding trimethylphosphine substituted carbene complex adds the cyclopentadienyl anion at the carbene carbon atom. A third reaction pathway is observed on treating with lithium
η 2个钨-Phosphinocarbebe配合物表现出对阴离子亲核试剂不同的行为。阳离子η 2种-phosphinocarbene复杂发生反应与苯硫酚阴离子PHS -经由羰基取代,而相应的三甲基膦取代卡宾络合物添加在卡宾碳原子的环戊二烯基阴离子。第三反应途径上治疗观察到的与二乙基氨基锂,提供一个中立η 2 -phosphinovinyl复杂。