The crystal structures of the 1-methyl-3,4-benzo-1-telluracyclopentane and 1-phenyl-1-telluracyclopentane cations in their tetraphenylborate salts,C8H8TeMe+ BPh4− and C4H8TePh+ BPh4−

The crystal structures of C₈H₈TeMe⁺ BPh₄^? (I) and C₄H₈TePh⁺ BPh₄^? (II) have been determined from three-dimensional X-ray counter data.I is monoclinic, space group P2₁/n with a 9.175(1), b 17.402(3), c 16.998(3) Å, β 98.92(6)°, Z = 4, R = 5.1% for 1641 observed reflections.II is triclinic, space group P$\text{1}$ with a 9.635(3), b 17.721(3), c 16.858(8) Å, α 89.77(2), β 104.36(4), γ 90.16(2)°, Z = 4, R = 9.0% for 6466 observed reflections.In both I and II tellurium is three-coordinate in a pyramidal geometry, with TeC distances in the range 2.07(1)–2.14(1) Å (I) and 2.10(1)–2.17(1) Å (II). In both structures short contacts of 3.4—3.5 Å occur between tellurium and carbon atoms of the tetraphenylborate anion.