Synthesis and structures of silicon-, germanium-, and tin-containing imido-alkyl molybdenum complexes (ArN)2Mo(CH2EMe3)2 (E = Si, Ge, Sn)

Abstract

New silicon , germanium , and tin containing imido alkyl molybdenum complexes (ArN) 2 Mo(CH 2 EMe 3 ) 2 (Ar is 2,6 diisopropylphenyl; E = Si (1), Ge (2), Sn (3)) were prepared in the crystalline state in 58-66% yields by the reactions of the (ArN) 2 MoCl 2 (DME) com plex with alkyllithium derivatives Me 3 ECH 2 Li (E = Si or Ge) or the Grignard reagents Me 3 ECH 2 MgCl (E = Ge or Sn). The structures of complexes 1-3 and the known analog (ArN) 2 Mo(CH 2 Bu t ) 2 (4) were established by X ray diffraction analysis. Complexes 1-3 were found to be isostructural. The coordination environment about the Mo atom can be described as a distorted tetrahedron. Complex 4 has a similar structure. The Mo-C distance tends to decrease with increasing electron donating ability of the EMe 3 group.

Synthesis and structures of silicon-, germanium- and tin-containing tungsten imido alkyl complexes (ArN)2W(CH2EMe3)2 (E=Si, Ge, Sn)

“…However, the values indicate a shortening of the W-C distances in the series of -SiMe 3 , -GeMe 3 and -SnMe 3 derivatives. A similar trend of decreasing Mo-C distances was recently found for the molybdenum imido alkyl compounds (ArN) 2 -Mo(CH 2 EMe 3 ) 2 (E = Si, Ge, Sn) [4]. The E-C (methylene group) distances are 1.868(2)/1.878(2) Å for 1, 1.965(2)/ 1.959(3) Å for 2 and 2.162(3)/2.166(3) Å for 3.…”

“…The differences between the average E-C (methylene group) distances are slightly bigger than the differences between the covalent radii of Si (1.13 Å [5]), Ge (1.19 Å [5]) and Sn (1.36 Å [5]) atoms. The same situation was observed in the similar Mo complexes [4]. The W@N distances in 1-3 are in the range of 1.751(2)-1.762(2) Å .…”

“…The W@N distances in 1-3 are in the range of 1.751(2)-1.762(2) Å . The differences between the average W@N distances in 1-3 and the average distances Mo@N in Mo compexes [4] are close to the differences between ionic radii of W and Mo atoms (W 6+ = 0.56 Å and Mo 6+ = 0.55 Å for coordination number 4 [6]). The WNC and WCE angles in 1-3 (157.2(1)°-165.6(2)°and 113.6(1)°-117.5(1)°, respectively) (see Table 1) are close to the analogous angles in the corresponding Mo complexes [4].…”

Synthesis and some properties of 14 group element-containing alkylidene complexes of molybdenum and tungsten

“…Therefore, we attempted the synthesis of heteroelement-containing carbene complexes of molybdenum and tungsten by the reactions of silicon-, germanium-and tin-containing imido alkyl compounds (ArN) 2 M(CH 2 EMe 3 ) 2 (Ar ¼ 2; 6-Pr i 2 C 6 H 3 ; M = Mo. W; E = Si, Ge, Sn) [4,5] with triflic acid and hydrogen chloride. This method was successfully used for preparation of hydrocarbon imido alkylidene compounds of the type Alkyl-CH@M(NAr)(OTf) 2 (DME) (M = Mo, W; Alkyl = Bu t , PhMe 2 C) [2b, 6].…”