The synthesis, structure, and reactions of some simple unsaturated σ-hydrocarbylplatinum(II) complexes

Trimethyltin compounds Me₃Sn---R(R = CH=CH₂, CF=CF₂, or CCPh) are selective reagents for the synthesis of unsaturated hydrocarbyl derivatives such as trans-PtCl(R)(PPhEt₂)2, by R/Cl exchange or oxidative addition (e.g., to Pt(PPh₃)₃); single crystal X-ray analyses of two such compounds (R = CH=CH₂ or CCPh) show that the trans-influence of R has only a low sensitivity to hybridisation at carbon, with sp³ > sp sp².     

The molecular structure of di-t-butylamine, NH[C(CH3)3]2, as determined by gas-phase electron diffraction: an exceptionally sterically hindered amine

Gaseous di-t-butylamine, NHBu^t₂, has been studied by electron diffraction at a nozzle temperature of ca. 293 K. The diffraction data reveal that this amine is exceedingly hindered. Repulsive steric interactions between the Bu^t groups are mainly relieved by an opening of the CNC valence angle to 135(3)°. Evidence of steric strain may also be found in the non-zero tilts (2–3°) of the Bu^t groups, defining the angle of rotation of these groups about axes through the N-bonded carbon atoms orthogonal to the NC₂ plane. The N---C and C---C bonds, 1.467(13) and 1.561(6) Å, respectively, are on the other hand relatively unstrained. Other principal geometrical parameters are unexceptional: C---H = 1.103(10) Å, NCC = 111.3(1.5)° (mean value) and CCH = 106(2)°. The position of the N-bonded hydrogen atom relative to the NC₂ plane could not be determined. The torsional positions of the Bu^t groups, with respect to the N---C bonds, could not be derived from least-squares refinements. A large number of models with Bu^t groups in various fixed positions were considered; the best fit between the observed and theoretical intensity data was obtained with one Bu^t group being twisted 19° away from the position typified by one C---C bond of this group being anti to the remote N---C bond, and the other Bu^t group similarly twisted by 30°. When viewed along the N---C bonds, the Bu^t groups are twisted in the same direction. Viewed along the C(N)C axis, these groups come close to being staggered with respect to each other. The values of the above bond distances are those of r_a parameters. Parenthesized values denote error limits, being least-squares standard deviations multiplied by a factor of three.     

“Dibutylmagnesium”, a convenient reagent for the synthesis of useful organic magnesium reagents MgA2 including cyclopentadienyls,aryloxides, and amides. Preparation of Zr(C5H5)Cl3. X-ray structure of [Mg{μ-N(SiMe)3C6H4N}(SiMe3)-o(OEt2)]2

n-Heptane-soluble “di-butylmagnesium” (I) (a commercially available material, prepared by addition of LiBu^s to MgBuⁿCl, and subsequent addition of ca. 5% MgOct₂ⁿ) has been found to be a useful starting material for obtaining numerous organic magnesium compounds. This is illustrated by its reaction with a number of protic compounds HA to give in good yields Mg(C₅H₅)₂, Mg(C₅H₄Me)₂, or the new compounds MgA₂: IV (A = C₅H₄SiMe₃), V [A = C₅H₃(SiMe₃)₂], VII (A = OC₆H₂Bu₂^t-2,6-Me-4), and X [A₂ = N(SiMe₃)C₆H₄N(SiMe₃)-o(OEt₂)]. The value of such compounds MgA₂ as mild ligand transfer reagents is illustrated by the synthesis of Zr(C₅H₃X₂)Cl₃ (X = H or SiMe₃). Compound X was isolated from OEt₂ solution as the crystalline dimer

with two o-$\text{N}$(SiMe₃)C₆H₄$\text{N}$(SiMe₃) ligands bridging two magnesium atoms and a terminal OEt₂ ligand completing a distorted tetrahedral environment around each Mg. Some key parameters are: MgN_t 1.997(7), MgN_b 2.083(8), MgO 2.041(7) Å; OMgN_t 112.1(3), OMgN_b 119.7(3), and N_tMgN_b 118.5(3)°.     

Syntheses and structures of structurally diverse potassium beta-diketiminates derived from the ligand [(N(SiMe3)C(Ph))2CH

The compounds [K((mu-N(SiMe3)C(Ph))2CH)(thf)2]infinity 1, [K(mu-N(SiMe3)C(Ph)C(H)C(Ph)NH)L]2 [L = (thf)2 2, tmen 3], [K(mu-NSi(Me)2C(Ph)C(H)C(Ph)N)(thf)3]2 4 and [K(N(H)C(Ph))2CH](thf)0.5 5 have been prepared from K[(N(SiMe3)C(Ph))2CH] and the X-ray structures of 1-4 are reported.