Stereochemistry of some organic derivatives of Group Vb elements. Part VI. Crystal and molecular structure of µ-oxo-bis[perchloratotriphenylbismuth(V)]

Abstract

The structure of the title compound has been determined by X-ray methods. Crystals are monoclinic, space group P2,lc. with Z = 4 in a unit cell of dimensions a = 18.750(3), b = 10.108(2), c = 18.927(3) A, p = 92.19(1)".The structure was solved by the heavy-atom method and refined by block-diagonal least-squares methods to a residual R of 0.070 for 31 45 data considered observed. The structure contains well separated discrete molecules. The two bismuth atoms are linked by an oxygen bridge [mean Bi-O(br) 2.065(10) 8. Bi-O-Bi 142.4(7)"]. The configuration about the bismuth atoms is distorted trigonal bipyramidal with the oxygen atoms apical and phenyl groups equatorial. The perchlorate groups are weakly co-ordinated to the metal [mean Bi-O(perch1orate) 2.65(1) A], one being disordered. Other mean dimensions: Bi-C(Ph) 2.1 9(2) A, O(br)-Bi-C(Ph) 97.1 (I)", Bi-O-CI 132.3(8)'. N1G 2W1 THE class of compounds X*RIR,-O-RIR,*X (1; R = Ph or Me, 31 = Sb or Bi, X = halide, NO,, or pseudohalide) are well known,2-8 and their i.r. and conductance data have been interpreted in favour of non-ionic structures containing five-co-ordinate antimony and bismuth. A recent crystal structure analysis 2,3 has shown that for the compound [(Ph3Sb(N3)}20] coordination about the metal is close to regular trigonal bipyramidal. On the other hand, tetrahedral coordination about the metal, with ionic perchlorate groups, had been suggested, from i.r. studies, for [[R,Sb(ClO,)},O] iR = Ph (ref. 8) or Me (ref. 9):. reinvestigation of the i.r. spectra of these compounds and of [(Ph,Bi(ClO,)),O]and their hydrates has led to the postulation that the anhydrous perchlorate compounds have structures 4niilar to those of the series of compounds (l), and an S-ray analysis lo has established that [(Me3Sb(C10,)},0] also has a trigonal bipyramidal configuration at the Sb atoms. Since crystals of the anhydrous antimony compound could not be obtained in a satisfactory form, we have investigated the structure of the title bismuth compound in order to elucidate the stereochemistry at the metal atom and the nature of the perchlorate group environment in the solid. EXPERIMENTAL

Organometallic Mo–O–Bi complexes

“…This might be the effect of the diminished steric hindrance in 1 in comparison to I where a closer approach of the Cp à MoO À 3 moiety to the Bi V centre might be prevented by Ph M Cp * repulsive interactions. However, the Bi-O bonds are longer than those reported for the known l-oxo bridged dinuclear organobismuth(V) compounds [Ar 3 BiOBiAr 3 (Y) 2 ] (Y = ClO 4 À , CF 3 SO 3 À , Ar = Ph; Y = Cl À , Ar = 4-(Me 2 N)C 6 H 4 ), covering a range from 2.02-2.12 Å [11], which will be due to the ionic nature of the bonding in 1. [10].…”

Molekülverbindungen mit Mo‐O‐Bi‐Einheiten

“…Die Phenylringe besetzen die äquatorialen Koordinationsstellen in einer für Ph 3 BiX 2 ‐Strukturen üblichen Weise 11a. Die Mo‐O‐Bi‐Einheiten sind gewinkelt (Mo1‐O1‐Bi 139.5(3)°, Mo2‐O4‐Bi 152.8(3)°), und die Bi‐O‐Abstände sind mit 2.198(6) (Bi‐O1) und 2.204(6) Å (Bi‐O4) etwas größer als diejenigen in den bekannten μ‐Oxo‐verbrückten zweikernigen Organobismut( V )‐Verbindungen des Typs [(Ar 3 BiY) 2 O] (2.02–2.12 Å; Y=ClO 4 − , CF 3 SO 3 − , Ar=Ph; Y=Cl − , Ar=4‐(Me 2 N)C 6 H 4 ) 11b–d. Dies mag daraus resultieren, dass die beiden Oxoliganden in 1 trans zueinander angeordnet sind und als starke π‐Acceptoren um dieselben Metallorbitale konkurrieren, wodurch sie ihre Bindungen gegenseitig schwächen.…”

Molecular Compounds with Mo‐O‐Bi Moieties

“…The phenyl rings occupy the equatorial positions in a typical manner for Ph 3 BiX 2 structures 11a. The Mo‐O‐Bi moieties are bent (Mo1‐O1‐Bi 139.5(3)°, Mo2‐O4‐Bi 152.8(3)°) and the BiO distances of 2.198(6) (BiO1) and 2.204(6) (BiO4) Å are somewhat longer than those reported for the known μ‐oxo‐bridged dinuclear organobismuth(V) compounds of the type [(Ar 3 BiY) 2 O] (Y=ClO 4 − , CF 3 SO 3 − , Ar=Ph; Y=Cl − , Ar=4‐(Me 2 N)C 6 H 4 ), which cover a range from 2.02 to 2.12 Å 11b–d. This is probably due to the fact that the two oxo ligands in 1 are located trans to each other and compete as strong π acceptors for the same orbitals (thereby mutually weakening their bonds), whereas in the other compounds mentioned the oxo ligands are positioned trans to weakly coordinating ligands; they can thus form stronger bonds.…”