Diorganobismuth(III) compounds with the pendant arm 2-(Me2NCH2)C6H4 ligand - Isothiocyanate, trifluoracetate and nitrate

The reaction of R2BiCl (1) [R = 2-(Me2NCH2)C6H4] with NaSCN, AgO2CCF3 or AgNO3 (1:1 M ratio) gave R2BiNCS (2), R2BiO(O)CCF3 (3) and R2BiNO3 (4), respectively. The new compounds were investigated by IR, 1H and 13C NMR spectroscopies as well as mass spectrometry. The structures of 2–4 were determined by single crystal X-ray diffraction. Both nitrogen atoms from the pendant arms are involved in intramolecular N→Bi coordination of different strength. For the isothiocyanate 2 this results in a distorted square-pyramidal (C,N)2BiN core. In the case of the trifluoroacetate 3 and the nitrate 4 the oxo anions can be considered as acting as monometallic biconnective (chelating) ligands [i.e. coordinated strongly asymmetric to Bi atom through oxygen atoms - Bi–O 2.379(12)/3.317(15) Å for 3, and 2.476(5)/3.088(5) Å for 4]. Thus, distorted pentagonal-pyramidal (C,N)2BiO2 cores can be considered for both compounds. All compounds exhibit chirality due to intramolecular coordination and crystallize as racemic mixtures. Chain polymer associations, based on weak C–H···Phcentroid interactions between molecular units, were found in the crystals of 2 and 3. In the crystal of 4 the molecules are held together into dimer units through weak Bi···Phcentroid and O···H interactions and these dimers are further associated into layers through weak C–H···Phcentroid and O···H interactions.

The diarylbismuth(III) compounds [2-(Me2NCH2)C6H4]2BiX [X = NCS, O(O)CCF3, NO3] are basically molecular species, the intramolecular N→Bi coordination of both pendant arms preventing the formation of polymeric compounds based on bridging anionic ligands. In solid state the chiral molecules are associated through weak C–H···Phcentroid and Bi···Phcentroid interactions.Figure optionsDownload as PowerPoint slideHighlights
► Chiral, hypervalent [2-(Me2NCH2)C6H4]2BiX [X = NCS, O(O)CCF3, NO3] species were obtained and characterized.
► Intramolecular N→Bi coordination prevents the formation of polymeric species built through bridging anionic ligands.
► First molecular diorganobismuth(III) isothiocyanate.
► First molecular diorganobismuth(III) nitrate.