18399-60-5Relevant academic research and scientific papers
Main group compounds as amphoteric ligands to transition metals. Synthesis and molecular structure of Cr(CO)5[PPh2CH2Ga(CH2CMe 3)2·NMe3]
Beachley Jr.,Banks, Michael A.,Kopasz, John P.,Rogers, Robin D.
, p. 5170 - 5174 (2008/10/08)
The reactivities of the group 13 compounds, R2MCH2PPh2 and R2MPPh2, as amphoteric ligands to transition metals have been investigated. The ligands R2MCH2PPh2 (R = CH2-CMe3, CH2SiMe3; M = Ga, In) reacted readily with Cr(CO)5NMe3 in benzene solution to form Cr(CO)5[PPh2CH2MR2·NMe 3], whereas for ligands of the type R2MPPh2 (R = CH2CMe3, CH2SiMe3; M = Al, Ga, In), only the two aluminum compounds and (Me3CCH2)2GaPPh2 formed isolable products of the type Cr(CO)5[PPh2MR2·NMe3]. However, the gallium and indium ligands with (trimethylsilyl)methyl substituents (Me3SiCH2)2MPPh2 reacted with NEt4Mr(CO)5Cl (MT = Cr, Mo, W) to form products of the type NEt4MT(CO)5[PPh2MR2Cl]. All new compounds were characterized by their physical properties, C and H analyses, and 1H and 31P NMR and IR spectral properties. The identity of NEt4Cr(CO)5[PPh2In(CH2SiMe 3)2-Cl] was further confirmed by the subsequent identification of products from reactions with anhydrous HCl and with MeI. In addition, Cr(CO)5[PPh2CH2Ga(CH2CMe 3)2·NMe3] was characterized by an X-ray structural study.
The reaction chemistry of transition-metal diphenylphosphorus complexes with organoaluminum compounds. The synthesis, characterization, and crystal and molecular structure of Cr(CO)5[PPh2(CH2)4OAl(CH 2SiMe3)2], an example of THF cleavage
Tessier-Youngs,Youngs, Wiley J.,Beachley Jr.,Churchill, Melvyn Rowen
, p. 1128 - 1138 (2008/10/08)
Metathetical and small molecule elimination reactions between appropriate transition-metal carbonyl diphenylphosphorus complexes and organoaluminum compounds have been investigated as synthetic routes to transition-metal derivatives of amphoteric ligands. The synthesis, characterization, and properties of the starting compounds for the metathetical reactions M(CO)5PPh2K·n(dioxane) (M = Cr, W, n = 2; M = Mo, n = 1) from M(CO)5PPh2H and KH are described. All data confirm that the dioxane molecules in these complexes retain their identity as cyclic ethers. Subsequent reactions of Cr(CO)5PPh2K·2(dioxane) with AlR2Br (R = Br, Me, Et, CH2SiMe3) in THF lead to the formation of high yields of fully characterized compounds with the empirical formula Cr(CO)5[PPh2(CH2)4OAlR2]. The (CH2)4O unit arises from the cleavage of the THF molecule. No THF-aluminum adducts are observed. The compound Cr(CO)5-[PPh2(CH2)4OAl(CH 2SiMe3)2] which incorporates a new amphoteric ligand has also been characterized by an X-ray structural study. The crystal is composed of dimeric units of formula [Cr(CO)5[PPh2-(CH2)4OAl(CH 2SiMe3)2]]2 which are in the centrosymmetric monoclinic space group P21/n with a = 11.939 (3) A?, b = 14.940 (A?), c = 21.014 (5) A?, β= 102.88 (2)°, V = 3654 A?3, Z = 2 (dimeric units), and mol wt 1301.5. Diffraction data (20(max) = 35°, Mo Kα radiation) were collected with a Syntex P21 automated four-circle diffractometer, the structure was solved by Patterson and difference-Fourier techniques, and the model was refined to RF = 9.2% and RwF = 8.2% for 1515 reflections with |Fo| > 3σ(|Fo|). The dimeric molecule lies on an inversion center. Each octahedral (OC)5CrPPh2- fragment is linked by an -(CH2)4O-unit (formed by cleavage of THF) to the two Al(CH2SiMe3)2 fragments. The central Al-O-Al-O ring is strictly planar, with obtuse Al-O-Al angles of 100.3 (6)° and acute O-Al-O angles of 79.7 (5)°. The second route to chromium derivatives of amphoteric aluminum-phosphorus ligands, small molecule elimination reactions between Cr(CO)5PPh2H and AlMe3 or AlMe2H, does not lead to compounds with Cr-P-Al bonds. Our observations suggest that the major site of reaction for the aluminum compounds is the carbonyl ligand.
Transition-metal complexes of organoaluminum phosphides. Synthesis, characterization, and crystal and molecular structure of Cr(CO)5[PPh2Al(CH2SiMe3) 2·NMe3]
Tessier-Youngs, Claire,Bueno, Clifford,Beachley Jr.,Churchill, Melvyn Rowen
, p. 1054 - 1059 (2008/10/08)
The reactions of organoaluminum phosphides with a variety of transition-metal carbonyl complexes containing labile ligands have been investigated. The reaction of Cr(CO)5NMe3 with (Me3SiCH2)2AlPPh2 in benzene solution leads to the formation of Cr(CO)5[PPh2Al(CH2SiMe2) 2·NMe3], a fully characterized new compound. An X-ray structural study has identified discrete isolated molecules of Cr(CO)5[PPh2Al(CH2SiMe3) 2·NMe3], separated by normal van der Waals distances, in the monoclinic crystal space group P21/n with a = 11.839 (4) A?, b = 18.517 (5) A?, c = 16.158 (4) A?, β = 90.32 (2)°, and ρ(calcd) = 1.20 g/cm3 for Z = 4 with molecular weight 637.82. Diffraction data were collected with a Syntex P21 diffractometer, and the structure was refined to RF = 6.4% for all 4948 reflections. There are no abnormally short intermolecular contacts. The unusual features identified in the investigation are the long bond distances for Al-P of 2.485 (1) A? and Cr-P of 2.482 (1) A?. The Al-N bond seems to be normal. The geometry about the tetrahedrally coordinated phosphorus atom is decidedly irregular. Similarly, the aluminum atom has a rather distorted tetrahedral environment. The reaction of Cr(CO)5[PPh2Al(CH2SiMe3) 2·NMe2] with anhydrous HBr leads to the formation of Cr(CO)5PPh2H, Br3AlNMe3, and SiMe4. A likely path for this reaction involves the initial cleavage of the long P-Al bond. In attempts to find other preparative reactions to compounds with a Cr-P-Al bond sequence, the related reactions of Cr(CO)5L (L = CO, CH3CN, THF) with R2AlPPh2 (R = Me, Et) were studied but the desired compounds were not formed. Available data suggest that the labile ligand on chromium was attacked by the aluminum-phosphorus reagent.
1H, 13C and 31P NMR studies of some (C6H5)3-nPRn and (C6H5)3-nPRnCr(CO)5 (n=0-3; R=H, CH3, C2H5, i-C3H7, t-C4H9) derivatives
Vincent, E.,Verdonck, L.,Kelen, G. P. van der
, p. 699 - 704 (2007/10/02)
The 31P chemical shift of the (C6H5)3-nPRn and (C6H5)3-nPRnCr(CO)5 (n=0-3; R=H, CH3, C2H5, i-C3H7, t-C4H9) derivatives is dominated by the steric effect.A small inductive effect is also operative but there are no indications of notable (dCrdp)? back-bonding.The 13C chemical shift of the phenyl carbon atons indicates that (pring-dp)? electron delocalization is unimportant.The 13C chemical shift of the carbonyl atoms, which is mainly governed by the mean excitation energy, confirms the conclusion that there are no notable changes in (dCrdp)? back-bonding in this series of compounds.
SYNTHESIS AND INFRARED STUDY OF (C6H5)nPX3-nCr(CO)5 (X=Cl, Br, I, H; n=0-3) AND (C6H5)2PRCr(CO)5 (R=METHYL, ETHYL, i-PROPYL, t-BUTYL) COMPOUNDS
Vincent, E.,Verdonck, L.,Kelen, G. P. van der
, p. 33 - 40 (2007/10/02)
A method for the preparation of (C6H5)nPX3-nCr(CO)5 complexes in the crystalline state is described.The carbon-oxygen stretching vibration, νCO(A1 eq.), of the complexes with X=Cl, Br, I is mainly determined by the inductive effect of the (C6H5)nPX3-n group.For X=H, the νCO band is defined by the concomitant influence of the ?, ? and steric effects.
