Synthesis, Characterization, and Solution Redox Properties of (trimpsi)M(CO)2(NO) Complexes [M = V, Nb, Ta; trimpsi = tBuSi(CH2PMe2)3]
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- 作者：Trevor W. Hayton ; P. James Daff ; Peter Legzdins ; Steven J. Rettig ; and Brian O. Patrick
- 刊名：Inorganic Chemistry
- 出版年：2002
- 出版时间：August 12, 2002
- 年：2002
- 卷：41
- 期：16
- 页码：4114 - 4126
- 全文大小：259K
- 年卷期：v.41,no.16(August 12, 2002)
- ISSN：1520-510X
文摘
Treatment of [Et4N][M(CO)6] (M = Nb, Ta) with I2 in DME at -78 
C produces solutions of the bimetallic anions[M2(
-I)3(CO)8]-. Addition of the tripodal phosphine tBuSi(CH2PMe2)3 (trimpsi) followed by refluxing affords(trimpsi)M(CO)3I [M = Nb (1), Ta (2)], which are isolable in good yields as air-stable, orange-red microcrystallinesolids. Reduction of these complexes with 2 equiv of Na/Hg, followed by treatment with Diazald in THF, results inthe formation of (trimpsi)M(CO)2(NO) [M = Nb (3), Ta (4)] in high isolated yields. The congeneric vanadium complex,(trimpsi)V(CO)2(NO) (5), can be prepared by reacting [Et4N][V(CO)6] with [NO][BF4] in CH2Cl2 to form V(CO)5(NO).These solutions are treated with 1 equiv of trimpsi to obtain (
2-trimpsi)V(CO)3(NO). Refluxing orange THF solutionsof this material affords 5 in moderate yields. Reaction of (trimpsi)VCl3(THF) (6) with 4 equiv of sodium naphthalenidein THF in the presence of excess CO provides [Et4N][(trimpsi)V(CO)3] (7), (trimpsi)V(CO)3H, and [(trimpsi)V(-Cl)3V(trimpsi)][(2-trimpsi)V(CO)4]·3THF ([8][9]·3THF). All new complexes have been characterized by conventionalspectroscopic methods, and the solid-state molecular structures of 2·1/2THF, 3-5, and [8][9]·3THF have beenestablished by X-ray diffraction analyses. The solution redox properties of 3-5 have also been investigated bycyclic voltammetry. Cyclic voltammograms of 3 and 4 both exhibit an irreversible oxidation feature in CH2Cl2 (Ep,a= -0.71 V at 0.5 V/s for 3, while Ep,a = -0.55 V at 0.5 V/s for 4), while cyclic voltammograms of 5 in CH2Cl2 showa reversible oxidation feature (E1/2 = -0.74 V) followed by an irreversible feature (0.61 V at 0.5 V/s). The reversiblefeature corresponds to the formation of the 17e cation [(trimpsi)V(CO)2(NO)]+ ([5]+), and the irreversible featurelikely involves the oxidation of [5]+ to an unstable 16e dication. Treatment of 5 with [Cp2Fe][BF4] in CH2Cl2 generates[5][BF4], which slowly decomposes once formed. Nevertheless, [5][BF4] has been characterized by IR and ESRspectroscopies.
C produces solutions of the bimetallic anions[M2(-I)3(CO)8]-. Addition of the tripodal phosphine tBuSi(CH2PMe2)3 (trimpsi) followed by refluxing affords(trimpsi)M(CO)3I [M = Nb (1), Ta (2)], which are isolable in good yields as air-stable, orange-red microcrystallinesolids. Reduction of these complexes with 2 equiv of Na/Hg, followed by treatment with Diazald in THF, results inthe formation of (trimpsi)M(CO)2(NO) [M = Nb (3), Ta (4)] in high isolated yields. The congeneric vanadium complex,(trimpsi)V(CO)2(NO) (5), can be prepared by reacting [Et4N][V(CO)6] with [NO][BF4] in CH2Cl2 to form V(CO)5(NO).These solutions are treated with 1 equiv of trimpsi to obtain (2-trimpsi)V(CO)3(NO). Refluxing orange THF solutionsof this material affords 5 in moderate yields. Reaction of (trimpsi)VCl3(THF) (6) with 4 equiv of sodium naphthalenidein THF in the presence of excess CO provides [Et4N][(trimpsi)V(CO)3] (7), (trimpsi)V(CO)3H, and [(trimpsi)V(-Cl)3V(trimpsi)][(2-trimpsi)V(CO)4]·3THF ([8][9]·3THF). All new complexes have been characterized by conventionalspectroscopic methods, and the solid-state molecular structures of 2·1/2THF, 3-5, and [8][9]·3THF have beenestablished by X-ray diffraction analyses. The solution redox properties of 3-5 have also been investigated bycyclic voltammetry. Cyclic voltammograms of 3 and 4 both exhibit an irreversible oxidation feature in CH2Cl2 (Ep,a= -0.71 V at 0.5 V/s for 3, while Ep,a = -0.55 V at 0.5 V/s for 4), while cyclic voltammograms of 5 in CH2Cl2 showa reversible oxidation feature (E1/2 = -0.74 V) followed by an irreversible feature (0.61 V at 0.5 V/s). The reversiblefeature corresponds to the formation of the 17e cation [(trimpsi)V(CO)2(NO)]+ ([5]+), and the irreversible featurelikely involves the oxidation of [5]+ to an unstable 16e dication. Treatment of 5 with [Cp2Fe][BF4] in CH2Cl2 generates[5][BF4], which slowly decomposes once formed. Nevertheless, [5][BF4] has been characterized by IR and ESRspectroscopies.