Cleavage of Ge–Ge and Sn–Sn Triple Bonds in Heavy Group 14 Element Alkyne Analogues (EAr^iPr₄)₂ (E = Ge, Sn; Ar^iPr₄ = C₆H₃-2,6(C₆H₃-2,6-ⁱPr₂)₂) by Reaction with Group 6 Carbonyls

Abstract

The reactions of heavier group 14 element alkyne analogues (EAr iPr4 )2 (E = Ge, Sn; Ar iPr4 = C6H3-2,6-(C6H3-2,6-i Pr2)2) with the group 6 transition metal carbonyls M(CO)6 (M = Cr, Mo, W)under UV irradiation resulted in the cleavage of the E-E bond and the formation of complexes {Ar iPr4 EM(CO)4}2 (1-6) that were characterized by single crystal X-ray diffraction as well as by IR and multinuclear NMR spectroscopies. Single crystal X-ray structural analyses of 1-6 showed that the complexes have a nearly planar rhomboid M2E2 core with three-coordinate group 14 atoms. The coordination geometry at the group 6 metals is distorted octahedral formed by four carbonyl groups as well as two bridging EAr iPr4 units. IR spectroscopic data suggest that the EAr iPr4 units are not very efficient -acceptors, but the investigation of E-M metal-metal interactions in 1-6 with computational methods revealed the importance of both σ-and -type contributions to bonding. The mechanism for the insertion of transition metal carbonyls into E-E bonds in (EAr iPr4 )2 was also probed computationally.2

Reactivity of a Base-Stabilized Germanium(I) Dimer toward Group 9 Metal(I) Chloride and Dimanganese Decacarbonyl

“…Similar Ge 2 M 2 rings can be found in the reaction of the digermyne [Ar Pri4 Ge] 2 (Ar Pri4 = 2,6-Ar 2 C 6 H 3 , Ar = 2,6-iPr 2 C 6 H 3 ) with M(CO) 6 (M = Cr, Mo, W) under UV irradiation to form [Ar Pri4 GeM(CO) 4 ] 2 , but the reaction mechanisms are unknown as of yet. 19 The Ge1 and Ge1A atoms, which adopt a distorted tetrahedral geometry, are coordinated with the bidentate 2-imino-5,6-methylenedioxylphenyl ligand and two manganese (Mn1 and Mn1A) atoms. The latter are also bonded to four CO moieties to adopt an octahedral geometry.…”

Reversible Sn–Sn Triple Bond Dissociation in a Distannyne: Support for Charge-Shift Bonding Character

“…This yields nonbonded electron density at the group 14 atoms which results in bending of the geometry via interelectronic repulsion and a change in the relative energies and symmetries of the frontier orbitals from π (HOMO) and π* (LUMO) in the linear form to a π (HOMO) and n + (LUMO) in the trans-bent configuration. 4 This allows matching of the symmetry of the frontier orbitals of the dimetallynes with those of several important small molecules such as H 2 5−7 and ethylene 8 and also facilitates reactions with other molecules such as cyclopentadiene 9 and metal carbonyls 10 under mild conditions to yield products in which the E−E bonds are broken. Thus, the bonding models in Scheme 1 and the observed reaction patterns suggest that the E−E triple bonds are relatively weak despite the fact that the Sn−Sn bond distance in Ar iPr4 SnSnAr iPr4 , 2.6675(4)Å, 2d is shorter than the sum (2.8 Å) 11 of the single-bond covalent radii of tin (cf.…”

“…The green trace (b) is the Sn­(I) radical intermediate from by UV photolysis/thermolysis at 80 °C of Sn­(Ar i Pr4 ) 2 in benzene for ca. 30 min . Spectrometer settings: 15 K, 0.1 mW power (no saturation), microwave frequency, 9.38 GHz, conversion time, 40 ms, modulation amplitude, 0.8 mT, modulation frequency, 100 kHz.…”

Interactions of a Diplumbyne with Dinuclear Transition Metal Carbonyls to Afford Metalloplumbylenes

“…More recent work has shown that the above species can be synthesized by the metathesis of the dimetallynes REER (R = terphenyl; E = Ge, Sn, or Pb) with the single- or triple-bonded transition-metal species, (CO) 3 CpMo−MoCp­(CO) 3 or (CO) 2 CpMoMoCp­(CO) 2 , respectively . In addition, the distannyne and digermyne were reacted with the group six carbonyls M­(CO) 6 to form the cluster species {Ar i Pr 4 EM­(CO) 4 } 2 (E = Ge, Sn; Ar i Pr 4 = −C 6 H 3 –2,6-(C 6 H 3 –2,6- i Pr 3 ) 2 ) . However, the reactivity of diplumbynes toward simple transition metal carbonyls remains hardly explored.…”

“…. 20 However, the reactivity of diplumbynes toward simple transition metal carbonyls remains hardly explored. Herein, we report the syntheses and characterizations of metalloplumbylenes Mn(CO) 5 (PbAr ■ EXPERIMENTAL SECTION General Procedures.…”