A comparative study of the structure and bonding in heavier pnictinidene complexes [(ArE)M(CO)n] (E = As, Sb and Bi; M = Cr, Mo, W and Fe).

N,C,N-Chelated pnictinidenes ArE [where E = As (1), Sb (2) or Bi (3); Ar = C6H3-2,6-(CH[double bond, length as m-dash]Nt-Bu)2] were used as ligands for the coordination of transition metal carbonyls. Thus, the reaction of 1-3 with [M(CO)5THF] (where M = Cr, W) or [Mo(CO)5(Me3N)] gave complexes [(ArE)M(CO)5] [where E = As and M = Cr (1a), Mo (1b), W (1c); E = Sb and M = Cr (2a), Mo (2b), W (2c); E = Bi and M = Cr (3a), Mo (3b), W (3c)]. Analogously, the treatment of 1-3 with [Fe2(CO)9] resulted in the formation of the complexes [(ArE)Fe(CO)4] [where E = As (1d), Sb (2d) or Bi (3d)]. All compounds were characterized by 1H and 13C NMR spectroscopy, Raman, IR and UV-Vis spectroscopy. The molecular structures of the majority of the compounds (except 1b and 1c) were also determined by the single-crystal X-ray diffraction analysis. Furthermore, the structure and bonding of the title compounds have also been thoroughly investigated using a computational approach.

Different Products of the Reduction of (N),C,N-Chelated Antimony(III) Compounds: Competitive Formation of Monomeric Stibinidenes versus 1H-2,1-Benzazastiboles.

The reduction of N,C,N-chelated antimony(III) chlorides [C6 H3 -2,6-(CH=NR)2 ]SbCl2 (R=Ph (1), tBu (2), Dip (3); Dip=2,6-iPr2 C6 H3 ) with an appropriate amount of KC8 or Li[AlH4 ] resulted in the formation of rare examples of monomeric stibinidenes [C6 H3 -2,6-(CH=NR)2 ]Sb (R=Ph (4), tBu (5), Dip (6)). Similarly, the reduction of compounds 1 or 2 by two equivalents of K[B(sBu)3 H] led to the stibinidenes 4 and 5. In contrast, the analogous reaction of compound 3 resulted in the formation of an unprecedented stibinidene [C6 H3 -2-(CH=NR)-6-(CH2 NHR)]Sb (7) (R=Dip), in which the hydrogen atoms that come from the K[B(sBu)3 H] are incorporated into the ligand backbone. To gain further insight into this intriguing reactivity with K[B(sBu)3 H] and to assess the influence of the substitution at both the antimony atom and pendant substituents, we prepared compounds [C6 H3 -2-(CH=NDip)]Sb(Ph)Cl (8) and [C6 H2 -2-(CH=NDip)-4,6-(tBu)2 ]SbCl2 (9). The treatment of compound 8 with K[B(sBu)3 H] smoothly led to the 1-Ph-2-Dip-1H-2,1-benzazastibole (11), whereas the reaction of compound 9 with K[B(sBu)3 H] resulted in either tBu-substituted 1-Cl-2-Dip-1H-2,1-benzazastibole (13) or the formation of unprecedented Sb-Sb dimer bis(2-Dip-1H-2,1-benzazastibole) (12) depending on the reaction stoichiometry. The miscellaneous reactivity of antimony(III) precursors with reducing agents together with the structure and bonding of the resulting products has also been investigated from a theoretical point of view.

Stibinidene and Bismuthinidene as Two-Electron Donors for Transition Metals (Co and Mn).

The reaction of stibinidene and bismuthinidene ArM [where Ar=C6 H3 -2,6-(CH=NtBu)2 ; M=Sb (1), Bi (2)] with transition metal (TM) carbonyls Co2 (CO)8 and Mn2 (CO)10 produced unprecedented ionic complexes [(ArM)2 Co(CO)3 ](+) [Co(CO)4 ](-) and [(ArM)2 Mn(CO)4 ](+) [Mn(CO)5 ](-) [where M=Sb (3, 5), Bi (4, 6)]. The pnictinidenes 1 and 2 behaved as two-electron donors in this set of compounds. Besides the M→TM bonds, the topological analysis also revealed a number of secondary interactions contributing to the stabilization of cationic parts of titled complexes.

From Dibismuthenes to Three- and Two-Coordinated Bismuthinidenes by Fine Ligand Tuning: Evidence for Aromatic BiC3N Rings through a Combined Experimental and Theoretical Study.

The reduction of N,C,N-chelated bismuth chlorides [C6H3-2,6-(CH=NR)2]BiCl2 [where R = tBu (1), 2',6'-Me2C6H3 (2), or 4'-Me2NC6H4 (3)] or N,C-chelated analogues [C6H2-2-(CH=N-2',6'-iPr2C6H3)-4,6-(tBu)2]BiCl2 (4) and [C6H2-2-(CH2NEt2)-4,6-(tBu)2]BiCl2 (5) is reported. Reduction of compounds 1-3 gave monomeric N,C,N-chelated bismuthinidenes [C6H3-2,6-(CH=NR)2]Bi [where R = tBu (6), 2',6'-Me2C6H3 (7) or 4'-Me2NC6H4 (8)]. Similarly, the reduction of 4 led to the isolation of the compound [C6H2-2-(CH=N-2',6'-iPr2C6H3)-4,6-(tBu)2]Bi (9) as an unprecedented two-coordinated bismuthinidene that has been structurally characterized. In contrast, the dibismuthene {[C6H2-2-(CH2NEt2)-4,6-(tBu)2]Bi}2 (10) was obtained by the reduction of 5. Compounds 6-10 were characterized by using (1)H and (13)C NMR spectroscopy and their structures, except for 7, were determined with the help of single-crystal X-ray diffraction analysis. It is clear that the structure of the reduced products (bismuthinidene versus dibismuthene) is ligand-dependent and particularly influenced by the strength of the N→Bi intramolecular interaction(s). Therefore, a theoretical survey describing the bonding situation in the studied compounds and related bismuth(I) systems is included. Importantly, we found that the C3NBi chelating ring in the two-coordinated bismuthinidene 9 exhibits significant aromatic character by delocalization of the bismuth lone pair.

Antimony(III) and bismuth(III) amides containing pendant N-donor groups--a combined experimental and theoretical study.

N,N- and N,N,N-chelated antimony(III) and bismuth(III) chlorides L(1-3)MCl2 1-4 [for L(1): M = Sb (1), for L(2): M = Sb (2) and for L(3): M = Sb (3) and Bi (4)], containing ligands L(1-3) derived from the pyrrole ring (where L(1) = C4H3N-2-(CH[double bond, length as m-dash]N-2',6'-iPr2C6H3), L(2) = C4H2N-2,5-(CH2NMe2)2, L(3) = C4H2N-2,5-(CH2NC4H8)2), were prepared by the treatment of lithium precursors with SbCl3 or BiCl3. Molecular structures 1-4 of were described both in solution (NMR spectroscopy) and in the solid state (single-crystal X-ray diffraction analysis). Structures of 1-4 were also subjected to a density functional theory study.