Die Kristallstruktur von N,N,N'-tris(trimethylsilyl)benzamidin sowie die Synthese und Kristallstruktur von DichIorantimon-N,N'-bis(trimethylsilyl)benzamidinat

Abstract

N,N,N'-Tris(trimethylsilyl)benzamidine, [C6H5-C(NSiMe3)N(SiMe3)2], reacts with antimony trichloride in CH2Cl2 solution to form monomeric dichloroantimony-N,N'-bis(trimethylsilyl)- benzamidine, [SbCl2(NSiMe3)2C-C6H5]. Both benzamidine derivatives have been character­ized by crystal structure determinations. [C6H5-C(NSiMe3)N(SiMe3)2]: space group P21/c, Z = 4, 2278 observed independent refle­xions, R = 0,038. Lattice dimensions (19 °C): a = 1521,0(1); b = 656.7(1); c = 2163,0(1) β = 94,21(1)°. The compound forms monomeric molecules with CN distances of 126,6 pm, and 141,0 pm, respectively, corresponding to C=N̄-SiMe3 and C-N(SiMe3)2 moieties. [SbCl2(NSiMe3)2C-C6H5]: space group P21/c, Z = 4, 2707 observed independent reflexions, R = 0,027. Lattice dimensions (19 °C): a = 1212,7(1); b = 962,1(1); c = 1728,9(1) pm; β = 98,02(1)°. The compound forms monomeric molecules in which the antimony atom is surrounded by two chlorine atoms, and by the N atoms of the benzamidine chelate, forming a distorted trigonal bipyramidal arrangement, which is a consequence of the steric effect of the lone pair on the Sb atom.

Synthesis, Electronic Properties, and Reactivity of Phospholes and 1,1′‐Biphospholes Bearing 2‐ or 3‐Thienyl C‐Substituents

“…The coordination geometry of 3 and 4 can be described as a heavily distorted “saw‐horse” conformation, in which the stereochemically active electron lone pair adopts an equatorial position. Analogous structural findings were reported for PhC(NSiMe 3 ) 2 SbCl 2 13a and guanidato dichloroarsines 10a. The N‐Sb‐F axis deviates significantly from linearity ( 3 : N1‐Sb1‐F2 141.08(5)°; 4 : N1‐Sb1‐F2 142.47(8)°) due to the larger steric demand of the electron lone pair.…”

Synthesis of a Molecule with Four Different Adjacent Pnictogens

“…The in‐plane Sb−Cl2 bond with a length of 2.3596(4) Å is slightly shorter than the out‐of‐plane Sb−Cl1 bond 2.3835(3) Å, which can be attributed to a hyperconjugative effect of the nitrogen lone pair interacting with the parallel‐lying σ*(Sb−Cl1) orbital (38 kJ mol −1 ) according to a natural bond orbital analysis . Such delocalization effects are also known from molecules consisting of [SbCl 2 ] moieties and amindinate or guanidinate substituents, or examples from our group, for example, Ter 2 N 3 SbCl 2 and Ter 2 N 2 PSbCl 2 . The As−P bond length (As1−P1 2.1444(4) Å) is in good agreement with the expected value for a double bond (Mes*‐As=P‐Mes* 2.141(5), Σ r cov (As=P)=2.16 Å), while both the As−N and Sb−N bond lengths compare well to polarized single bonds (As−N 1.850(1), Sb−N 2.055(1); cf.…”

Cyclo-Pnicta-triazanes: Biradicaloids or Zwitterions?

“…(2), 2.451(2) Å). Judged from the molecular geometry, the compounds 2 are closely related to known species incorporating guanidinate or amidinate substituents on pnictogen chloride moieties, which were investigated by the groups of Dehnicke, 41 Jones, 42 Schulz, 43 and Ragogna. 44 In 2E (E = As, Sb, Bi), a contact within the sum of van der Waals radii (E···centroid 3.234, 3.166, 2.971 Å) indicates additional stabilization due to weak interactions with the mesityl groups.…”