Bis(but-2-enoato-κO)triphenylbismuth(V)

In the title molecule, [Bi(C6H5)3(C4H5O2)2], the BiV atom is in a distorted trigonal–bipyramidal environment with carboxylate O atoms in axial positions and phenyl C atoms in the equatorial plane. The Bi—O bond lengths are 2.283 (3) and 2.309 (2) Å, but as a result of additional long Bi⋯O interactions [2.787 (3) and 2.734 (3) Å], one of the C—Bi—C angles is 148.62 (13)°. In the crystal, weak C—H⋯O hydrogen bonds connect pairs of molecules into inversion dimers. These dimers are further connected by weak C—H⋯π interactions into chains along [100] .

In the title molecule, [Bi(C 6 H 5 ) 3 (C 4 H 5 O 2 ) 2 ], the Bi V atom is in a distorted trigonal-bipyramidal environment with carboxylate O atoms in axial positions and phenyl C atoms in the equatorial plane. The Bi-O bond lengths are 2.283 (3) and 2.309 (2) Å , but as a result of additional long BiÁ Á ÁO interactions [2.787 (3) and 2.734 (3) Å ], one of the C-Bi-C angles is 148.62 (13) . In the crystal, weak C-HÁ Á ÁO hydrogen bonds connect pairs of molecules into inversion dimers. These dimers are further connected by weak C-HÁ Á Á interactions into chains along [100] .

Related literature
For the isotypic (C 6 H 5 ) 3 Sb(C 4 H 5 O 2 ) 2 structure, see: Gushchin et al. (2013). For closely related structures, see: Andreev et al. (2013);Belsky (1996). For the chemistry of triphenyantimony diacylates, see: Gushchin et al.   Table 1 Hydrogen-bond geometry (Å , ). phenylbismuth and triphenylantimony diacylates contain two double bonds C═C in the molecule, due to which they can be used for polymerization filling of polystyrene and polymethylmethacrylate. The title compound is a very promising monomer for developing metal-containing organic scintillators which have recently attracted much attention in highenergy physics. It was found that the participation of both acrylate groups in polymerization leads to cross-linking, considerably decreasing the thermooxidative destruction of the resulting polymer (Dodonov et al., 2004). Organic glasses based on triphenylantimony diacrylate and methylmethacrylate having increased fungal resistance are now available (Dodonov et al., 2004). The thermodynamic properties of triphenylantimony diacylates have been studied (Letyanina et al., 2012;Markin et al., 2011). The crystal structure and chemistry of a similar orgaonmetallic compound of antimony has been reported by Gushchin et al. (2013).

Experimental
The synthesis was carried out on the oxidation addition reaction of triphenylbismuth, crotonic acid and tert-butyl hydroperoxide. To a solution of 0.56 ml of 92.6% aqueous tert-butyl hydroperoxide and 0.86 g of crotonic acid in 20 ml of diethyl ether was added a solution of 2.2 g of triphenylbismuth. The mixture was kept for 24 h at room temperature. The yellow crystals formed were filtered off and dried to obtain 1.91 g (73%) of triphenylbismuth bis(but-2-enoate). The product was recrystallized twice from chloroform-hexane mixture (1:4), m.p. 426 K. A crystal for X-ray diffraction analysis was obtained from benzene solution. Refinement H atoms were positioned geometrically (C-H=0.95-1.00 Å) and refined using a riding model with the U iso (H)=1.2U eq (C) (1.5U eq (C) for methyl groups). In the refinment the anisotropic displacment parameters of atoms pairs C9/C10 and C16/C17 were restrained using the DELU instruction in SHELXL (Sheldrick, 2008).

Figure 1
The molecular structure of the title compound. Displacement ellipsoids are drawn at the 30% probability level. H atoms are presented as small spheres of arbitrary radius.  Hydrogen site location: inferred from neighbouring sites H-atom parameters constrained w = 1/[σ 2 (F o 2 ) + (0.0212P) 2 + 0.9058P] where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.001 Δρ max = 0.65 e Å −3 Δρ min = −0.84 e Å −3 Special details Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Bi 0.714269 (12)