From Pseudo-octahedral to Pseudo-trigonal Bipyramidal Configuration: Syntheses and Molecular Structures of 4-t-Bu-2,6-[(EtO)2P(O)]2C6H2BiCl2 and [1(Bi),3(P)-Bi(Cl)OP(O)(OEt)-5-t-Bu-7-P(O)(OEt)2]C6H2

The syntheses and molecular structures in solution and in the solid state of the intramolecularly coordinated organobismuth derivatives 4-t-Bu-2,6-[(EtO)2P(O)]2C6H2BiCl2 (1) and [1(Bi),3(P)-Bi(Cl)OP(O)(OEt)-5-t-Bu-7-P(O)(OEt)2]C6H2 (2) are reported. Compound 1 crystallizes in the triclinic space group P1̅ with two pairs of crystallographically independent molecules per unit cell. Each bismuth atom shows a distorted Ψ-octahedral CCl2O2Bi configuration with the chlorine and oxygen atoms mutually trans. The intramolecular Bi···O distances range between 2.378(5) and 2.414(5) Å. The phosphabismole derivative 2 forms a head-to-tail dimer via intermolecular PO→Bi interactions. Compound 2 crystallizes as a racemic mixture of (S P,A Bi) and (R P,C Bi) isomers. DFT calculations reveal the high s-character of the lone electron pairs at the bismuth atoms in compounds 1 and 2.