Tin(II) bromide

Chembox new
Name = Tin(II) bromide
ImageFile = Tin(II)_bromide.jpg
ImageName = Tin(II) bromide
OtherNames = tin dibromide, stannous bromide
Section1 = Chembox Identifiers
CASNo = 10031-24-0
Section2 = Chembox Properties
Formula = SnBr₂
MolarMass = 278.518 g/mol
Appearance = yellow powder
Density = 5.12 g/cm³, solid
Solubility = ?
MeltingPt = 215°C
BoilingPt = 639°C
Section3 = Chembox Structure
CrystalStruct = related to PbCl₂
Section7 = Chembox Hazards
EUClass = not listed

Tin(II) bromide is a chemical compound of tin and bromine with a chemical formula of SnBr₂. Tin is in the +2 oxidation state. The stability of tin compounds in this oxidation state is attributed to the inert pair effect. Greenwood&Earnshaw]

tructure 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. [ J.L Wardell "Tin:Inorganic Chemistry" "Encyclopedia of Inorganic Chemistry" Ed: R Bruce King John Wiley & Sons (1994) ISBN 0-4719-3620-0] There is evidence of dimerisation in the gaseous phase. [cite journal
title = Thermochemistry of tetrabromoditin and bromoiodotin gaseous
author = K. Hilpert, M. Miller, F. Ramondo
journal =J. Phys. Chem.
year = 1991
volume = 95
issue = 19
pages = 7261–7266
doi = 10.1021/j100172a031] 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. [cite journal
title = Inert Pair Effects in Tin and Lead Dihalides: Crystal Structure of Tin(II) Bromide
author = Abrahams I.; Demetriou D.Z.
journal =Journal of Solid State Chemistry
year = 2000
volume = 149
issue = 1
pages = 28–32
doi = 10.1006/jssc.1999.8489]

Preparation

Tin(II) bromide can be prepared by the reaction of metallic tin and HBr distilling off the H₂O/HBr and coolingCotton&Wilkinson6th] ::Sn + 2HBr→ SnBr₂ + H₂

Reactions

SnBr₂ is soluble in donor solvents such as acetone, pyridine and dimethylsulfoxide to give pyramidal adducts
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. Greenwood&Earnshaw] When dissolved in HBr the pyramidal SnBr₃⁻ ion is formed.Like SnCl₂ it is a reducing agent. With a variety of alkyl bromides oxidative addition can occur to yield the alkyltin tribromide [cite journal
title = A convenient synthesis of (C₁-C₁₈) alkyltin tribromides
author = Bulten E.J.
journal = Journal of Oganometallic Chemistv
year = 1975
volume = 97
issue = 1
pages = 167–172] 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 [cite journal
title = Synthesis and studies of trimethylamine adducts with tin(II) halides
author = Chung Chun Hsu and R. A. Geanangel
journal = Inorg. Chem.
year = 1977
volume = 16
issue = 1
pages = 2529–2534
doi = 10.1021/ic50176a022] 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. [cite journal
title = Donor and acceptor behavior of divalent tin compounds
author = Chung Chun Hsu and R. A. Geanangel
journal = Inorg. Chem.
year = 1980
volume = 19
issue = 1
pages = 110–119
doi = 10.1021/ic50203a024]

References