Tin(II) bromide

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Tin(II) bromide

part of an (SnBr2)∞ chain in the solid state[1]
Names
Other names
tin dibromide, stannous bromide
Identifiers
3D model (
JSmol
)
ChemSpider
ECHA InfoCard
 100.030.067 Edit this at Wikidata
EC Number
  • 233-087-0
UNII
  • InChI=1S/2BrH.Sn/h2*1H;/q;;+2/p-2 ☒N
    Key: ZSUXOVNWDZTCFN-UHFFFAOYSA-L ☒N
  • InChI=1/2BrH.Sn/h2*1H;/q;;+2/p-2
    Key: ZSUXOVNWDZTCFN-NUQVWONBAM
  • Br[Sn]Br
Properties
SnBr2
Molar mass 278.518 g/mol
Appearance yellow powder
Density 5.12 g/cm3, solid
Melting point 215 °C (419 °F; 488 K)
Boiling point 639 °C (1,182 °F; 912 K)
Structure
related to PbCl2
Hazards
GHS labelling:[2]
GHS05: Corrosive
Danger
H314
P260, P264, P280, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P321, P363, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

Tin(II) bromide is a chemical compound of

inert pair effect.[3]

Structure and bonding

In the gas phase SnBr2 is non-linear with a bent configuration similar to SnCl2 in the gas phase. The Br-Sn-Br angle is 95° and the Sn-Br bond length is 255pm.[4] There is evidence of dimerisation in the gaseous phase.[5] The solid state structure is related to that of SnCl2 and PbCl2 and the tin atoms have five near bromine atom neighbours in an approximately trigonal bipyramidal configuration.[6] Two polymorphs exist: a room-temperature orthorhombic polymorph, and a high-temperature hexagonal polymorph. Both contain (SnBr2)∞ chains but the packing arrangement differs.[1]

orthorhombic polymorph[1][7]
hexagonal polymorph[1][8]

Preparation

Tin(II) bromide can be prepared by the reaction of metallic tin and HBr distilling off the H2O/HBr and cooling:[9]

Sn + 2 HBr → SnBr2 + H2

However, the reaction will produce tin (IV) bromide in the presence of oxygen.

Reactions

SnBr2 is soluble in donor solvents such as

dimethylsulfoxide to give pyramidal adducts.[9]

A number of hydrates are known, 2SnBr2·H2O, 3SnBr2·H2O & 6SnBr2·5H2O which in the solid phase have tin coordinated by a distorted trigonal prism of 6 bromine atoms with Br or H2O capping 1 or 2 faces.[3] When dissolved in HBr the pyramidal SnBr3− ion is formed.[3] Like SnCl2 it is a reducing agent. With a variety of alkyl bromides oxidative addition can occur to yield the alkyltin tribromide[10] e.g.

SnBr2 + RBr → RSnBr3

Tin(II) bromide can act as a

Lewis acid forming adducts with donor molecules e.g. trimethylamine
where it forms NMe3·SnBr2 and 2NMe3·SnBr2 [11] It can also act as both donor and acceptor in, for example, the complex F3B·SnBr2·NMe3 where it is a donor to boron trifluoride and an acceptor to trimethylamine.[12]

References

  1. ^
    doi:10.1002/zaac.201500108
    .
  2. ^ "Tin(II) bromide". pubchem.ncbi.nlm.nih.gov. Retrieved 12 December 2021.
  3. ^
    ISBN 978-0-08-037941-8
    .
  4. ISBN 0-471-93620-0
  5. doi:10.1021/j100172a031
    .
  6. doi:10.1006/jssc.1999.8489
    .
  7. ^ "ICSD Entry: 429132". Cambridge Structural Database: Access Structures. Cambridge Crystallographic Data Centre. Retrieved 2022-02-09.
  8. ^ "ICSD Entry: 429133". Cambridge Structural Database: Access Structures. Cambridge Crystallographic Data Centre. Retrieved 2022-02-09.
  9. ^
    ISBN 0-471-19957-5
  10. hdl:1874/15985
    .
  11. doi:10.1021/ic50176a022
    .
  12. doi:10.1021/ic50203a024
    .
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