Decaphenylgermanocene, -stannocene and -plumbocene, [gh 5-(C 6H 5) 5C 5] 2E II (E = Ge, Sn, Pb) and the X-ray crystal and molecular structure of pentaphenylstannocene, η 5-(C 6H 5) 5C 5SnC 5H 5-η 5

Abstract

The [(C 6H 5) 5C 5] − anion reacts with GeI 2, SnCl 2 or Pb(O 2CCH 3) 2 in ethereal solvents to form the sandwich compounds [η 5-(C 6H 5) 5C 5] 2E II (E = Ge (III), Sn (I) and Pb (IV)) in 60, 73 and 54% yields, respectively. The infusible air- and water-stable products (off-white, bright-yellow and deep-red colored, respectively) exhibit a weak parent ion in the mass spectrum plus the [(C 6H 5) 5C 5E] + cation (100%) and [(C 6H 5) 5C 5H] + and [(C 6H 5) 5C 5] +. The E = Pb derivative (IV) is thermochromic. The A 1u v asym ring—metal stretch is observed in the infrared at 164, 149 and 135 and the corresponding A 1g sym stretch at 153, 138 and 134 cm −1 in the Raman for III, I and IV, respectively. Pentaphenylstannocene (II) is formed in 23% yield from η 5-cyclopentadienyltin(II) chloride as light-yellow, monoclinic platelets which are moderately air-stable, decomposing at 150°C. The mass spectrum exhibits a weak parent ion plus the equally abundant [(C 6H 5) 5C 5Sn] + and [H 5C 5Sn] + cations. The 119mSn Mössbauer spectra at 78 K of deca- (I) and pentaphenylstannocene (II) ( IS = 3.75, 3.67; QS = 0.583, 0.868 mm s −1, respectively) are similar to other stannocenes. Pentaphenylstannocene (II), C 40H 30Sn, crystallizes with a molecule of toluene in the space group P2 1/ c with a 13.357(5), b 10.139(3), c 26.967(5) Å, β 100.96(2)°, V 3585(2) Å 3, Z = 4, ϱ calc 1.336 g cm −3. The structure was determined at 138(2) K using Mo- K α radiation to a final conventional R value of 0.038 and R w of 0.045 for 5220 observed reflections. The molecule is bent through 151.1(2)° between the tin vectors to the pentaphenylcyclopentadienyl (2.487(5) Å) 151.1(2)° between the tin vectors to the pentaphenylcyclopentadienyl (2.487(5) Å) and cyclopentadienyl (2.391(5) Å) ring centroids. The phenyl groups are not antiparallel to their cyclopentadienyl ring.