Carbaborane derivatives of the late- and post-transition elements. Part 3. Structural consequences of ligand substitution in palladadicarbadodecaboranes 3-L2-3,1,2-PdC2B9H11. The crystal and molecular structures of 3-[Me2N(CH2)2NMe2]-3,1,2-PdC2B9H11 and 3-(PMe3)2-3,1,2-PdC2B9H11

Abstract

The action of Tl⁺[3,1,2-TlC₂B₉H₁₁]^– on [PdCl₂(tmen)][tmen = Me₂N(CH₂)₂NMe₂] yields the aminometallacarbaborane 3-(tmen)-3,1,2-PdC₂B₉H₁₁(1) which possesses a ‘slipped’ structure, as shown by a single-crystal X-ray study [Pd–B 2.182(6), 2.202(5), and 2.182(6)Å and Pd–C 2.608(4) and 2.623(4)Å; a= 8.474 5(12), b= 12.363 6(19), c= 16.775 9(26)Å, β= 109.14(1)°, R= 0.03 for 2 070 independent observed reflections]. The diamine ligand may be displaced from complex (1) by cyclo-octa-1,5-diene, in the presence of HCl, and by trimethylphosphine, which in turn is displaced by trimethyl phosphite yielding the complexes 3-L₂-3,1,2-PdC₂B₉H₁₁{L₂= 1,5-C₈H₁₂, (PMe₃)₂(2), or [P(OMe)₃]₂}. The ¹¹B n.m.r. spectra are consistent with a more symmetrical structure for complex (2) than for (1) and this has been confirmed by an X-ray study which shows Pd–B 2.260(5), 2.315(5), and 2.249(4)Å, and Pd–C 2.414(4) and 2.492(4)Å; a= 6.718 3(10), b= 15.502 4(18), c= 17.918 4(24), β= 101.90(1)°, R= 0.026 for 2 214 independent observed reflections.