Ramesh N. Kapoor

Organometalloidal derivatives of the transition metals : VII. The thermal and photochemical properties of trialkyllead derivatives of Cr, Mo and W

Abstract Trimethyl- and tri ethyllead derivatives (η 5 -C 5 H 5 )M(CO) 3 PbR 3 (M  Cr, Mo, and W) have been synthesized. The trimethyllead derivatives are photochemically, and to a lesser extent, thermally unstable with respect to methyl transfer reactions that yield the corresponding (η 5 -C 5 H 5 )M(CO) 3 CH 3 complex. The related triethyllead complexes behave in a distinctly different fashion exhibiting rearrangements to [(η 5 -C 5 H 5 )M(CO) 3 ] 3 PbEt 2 (M  W, Mo). The reactions of the Cr, Mo, and W complexes with SO 2 yielded the corresponding alkyl sulphinato complexes as did the reaction of the related Fe complex [(η 5 -C 5 H 5 )Fe(CO) 2 PbEt 3 ].

Concerning the silicon-germanium bond. The structures of isomeric Ph3EE′Me3, E = Ge, E′ = Si and E = Si, E′ = Ge

Abstract The synthesis and structure of the unknown trimethylgermyltriphenylsilane (I, Ph 3 SiGeMe 3 ) is reported. The molecular geometry is compared to that of the isomeric Me 3 SiGePh 3 (II) and the related Ph 3 SiSiMe 3 (III) and (η 5 -C 5 H 5 )Fe(CO) 2 SiMe 2 GePh 3 (IV). The SiGe bond of I is significantly longer than that for II. We suggest that this is due to expansion of Ge bonding orbitals by the relatively electron-donating methyl groups in conjunction with the contraction of the corresponding orbitals of Si due to the electron-withdrawing phenyl groups. The overall result is a better orbital overlap between the Si and Ge atoms for II.

Pentamethyldisilylmethyl derivatives of the transition metals, LMCH2SiMe2SiMe3 [LM = (η5-C5R5)M(CO)nn−, M = Fe, W, R = H, Me, n = 2, 3; (η5-C9H7)Fe(CO)2−; (η5-C5 H5)2MCl−, M = Ti, Zr, Hf]

Abstract Pentamethyldisilylmethyl derivatives of the transition metals have been synthesized, LMCH2SiMe2SiMe3 [LM = (η5-C5R5) M(CO)n−, M = Fe, W, R = H, Me, n = 2, 3; (η5-C9H7)Fe(CO)2−; (η5-C5H5) 2MCl−, M = Ti,Zr,Hf]. The cyclopentadienylcarbonyl complexes are photochemically labile with respect to rearrangement to LM-SiMe2 CH2SiMe3 and are also subject to base-induced migration to the cyclopentadienyl ring to form (η5-Me3SiCH2SiMe2C5H4) derivatives. The titanium, zirconium and hafnium complexes exhibit neither property; the only compound isolated from the photochemical treatment of these complexes being Me3SiSiMe3. Structural analyses of (η5-C5H5)W(CO)3 CH2SiMe2SiMe3 and its phosphine-substituted rearrangement product, (η5-C5H5)W(CO)2 (PPh3)SiMe2CH2SiMe3, are presented.

Organometalloidal derivatives of the transition metals: X. Photochemical, thermal, and SO2induced 1,2-phenyl and 1,2-sulphinatophenyl migratons from lead to transition metals in the system [(η5-C5H5)M(CO)nPbPh3] (M = Fe, Cr, Mo, W)

Abstract The complexes [(η 5 -C 5 H 5 )M(CO) n PbPh 3 ] (M = Fe, Cr, Mo, W) have been studied with respect to their thermal and photochemical stability and their reactivity with respect to SO 2 . The iron complex is the only complex that exhibits the ability to decompose via a 1,2-phenyl migration to the transition metal under thermal conditions, but photochemically the tungsten complex also exhibits this behaviour. All complexes react readily with SO 2 to yield the corresponding sulphinatophenyl complexes, LMSO 2 Ph, in high yield.

Insertion reactions of t-Bu(η5-C5H5)Fe(CO)2

Abstract The complex t-Bu(η 5 -C 5 H 5 )FE(CO) 2 has been treated with triphenylphosphine in refluxing THF to produce t-BuCO(η 5 -C 5 H 5 )Fe(CO)(PPh 3 ). The large steric bulk of the t-butyl group suggests that this reaction should be faster than the reaction involving the methyl group, and a kinetic investigation illustrates this to be the case. The same steric bulk predicts that the reaction with SO 2 should be slow, and indeed we have been unable to effect the related SO 2 insertion reaction. Attempts to prepare the corresponding t-Bu(η 5 -C 5 H 5 )W(CO) 3 led to formation of the related isobutyl complex.

Decamethylpentasilacycloheptyne·Mo2(CO)4(η5-C5H5)2 and cycloheptyne·Mo2(CO)4(η5-C5H5)2

Abstract A dimolybdenum derivative of decamethylpentasilacycloheptyne (1) was synthesized by direct reaction of the heptyne with Mo2(CO)4(η5-C5H5)2. 1 crystallized in the space group P 1 , a=9.386(2), b=9.866(3), c=20.178(4) A, α=92.17(2), β=97.17(2), γ=115.71(2)°. The acetylenic bond is lengthened from 1.213 A in the free ligand to 1.359(4) A and all the Si–Si bond lengths in 1 are significantly lengthened upon complexation. This is due to relaxation of the ring strain as evidenced by the Si–C–C bond angles in 1 of 132.7 and 140.9° compared to 159.2 and 162.6° in the uncomplexed ring. 29Si-NMR data exhibit significant downfield chemical shifts upon complexation for the Si atoms adjacent to the triple bond, with moderate upfield shifts for the other Si atoms. The related cycloheptyne·Mo2(CO)4(η5-C5H5)2 (2) was synthesized by the reaction of cyclohepteno-1,2,3-selenadiazole with Mo2(CO)4(η5-C5H5)2. 2 crystallized in the space group C21/c, a=30.396(10), b=8.9093(3), c=16.156(4) A, β=115.39(2)°. The acetylenic bond in 2 is 1.345 A, compared with a calculated value (ab initio 3-21 G*) of 1.190 A for the free cycloheptyne.

Synthesis and structure of the iron-substituted silylacetylene [(η5-C5H5)Fe(CO)2SiMe2C]2 and its cobalt hexacarbonyl derivative [(η5-C5H5)Fe(CO)2SiMe2C]2 · Co2(CO)6

Abstract A transition metal-substituted silylacetylene [( η 5 -C 5 H 5 )Fe(CO) 2 SiMe 2 C] 2 , [FpMe 2 SiC] 2 ( I ) was synthesized and characterized spectroscopically and structurally. I crystallized in the monoclinic space group P 2 1 n , a = 13.011(3) A b = 12.912(3) A , c = 13.175(5) A , β = 94.95(2) . The acetylene linkage is reactive toward Co 2 (CO) 8 to form I . Co 2 (CO) 6 ( II ) which was also characterized spectroscopically and by single crystal X-ray diffraction. II crystallized in the orthorhombic space group Pbca, a = 17.64(2) A , b = 14.225(10) A , c = 24.49(2) A .

Organometalloidal derivatives of the transition metals: XXXIII. Reactions of ferrocenylcarboxaldehyde with base and trimethylsilylcyanide. A new high yield reaction for the formation of cyano-amines or silylethers☆

Abstract Treatment of ferrocenecarboxaldehyde with base at 0°C, lithium diisopropylamide (LDA) or n-butyllithium, followed by the addition of trimethylsilylcyanide, produced 1-(diisopropylamino)cyanomethylferrocene, FcCH(N{iPr}2(CN) (II) or 1-trimethyl-siloxy-n-pentylferrocene, FcCH(nBu)OSiMe3 (IIIa). The reaction of naphthaldehyde, NpCHO, with LDA/Me3SiCN led to formation of 1-(diisopropylamino)cyanomethylnaphthalene, NpCH{N(iPr)2}(CN) suggesting a general new synthesis for cyanoamines. The reaction of ferrocenecarboxaldehyde with Me3SiCN led to the expected silylether FcCH(CN)OSiMe3 (I). An alternative synthesis of ferrocenylmethylsilylethers, FcCH2OSiR3 (IV), involved the reaction of 1-ferrocenylmethanol with R3SiCl in the presence of pyridine. The basicity of the new silylethers III and IV is reported.

High Yield, One-Pot Syntheses of Symmetrical Diaryl- N , N -Dialkyl Carbamoylmethylphosphine Oxide (CMPO) Ligands

Abstract A simple one-pot high yield (˜70%) process is reported for the synthesis, in ˜100 g amounts, of a series of symmetrical diaryl-N,N-di-i-butylcarbamoylphosphine oxide (CMPO) actinide extractants, aryl = 4-t-butylphenyl, 4-trifluoromethylphenyl, 4-methoxyphenyl and 2,4,6-tri-i-propylphenyl.

Reactions of Chromyl Chloride with Carboxylic Acids and Carboxylic Acid Anhydrides

Abstract Chromyl Chloride reacts with carboxylic acids [RCOOH where R = C2H5, n-C3H7, CH2CI, CHCl2 and CCI3] to give reduced chromium(III) carboxylates, [Cr3 O(OOCR)6 (H2O)3 ]Cl. Magnetic susceptibility, UV-visible and IR measurements are all consistent with their trinuclear basic structures. Reactions of chromyl chloride with carboxylic acid anhydrides [(RCO)2O where R = CH3 , C2H5 and n-C3H7 ] give dinuclear oxo-bridged complexes of the type, [Cr2O(OOOCR)3 ]Cl. These compounds behave as non-electrolytes in polar organic solvents. IR spectra suggest the presence of bridging carboxylato groups containing Cr-O -Cr chains. Their low magnetic moment values suggest polymeric structures exhibiting antiferromagnetic coupling between Cr atoms.