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Tin(II) bromide

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Tin(II) bromide
part of an (SnBr2)∞ chain in the solid state
Names
Other names tin dibromide, stannous bromide
Identifiers
CAS Number
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.030.067 Edit this at Wikidata
EC Number
  • 233-087-0
PubChem CID
UNII
CompTox Dashboard (EPA)
InChI
  • InChI=1S/2BrH.Sn/h2*1H;/q;;+2/p-2Key: ZSUXOVNWDZTCFN-UHFFFAOYSA-L
  • InChI=1/2BrH.Sn/h2*1H;/q;;+2/p-2Key: ZSUXOVNWDZTCFN-NUQVWONBAM
SMILES
  • BrBr
Properties
Chemical formula SnBr2
Molar mass 278.518 g/mol
Appearance yellow powder
Density 5.12 g/cm, solid
Melting point 215 °C (419 °F; 488 K)
Boiling point 639 °C (1,182 °F; 912 K)
Structure
Crystal structure related to PbCl2
Hazards
GHS labelling:
Pictograms GHS05: Corrosive
Signal word Danger
Hazard statements H314
Precautionary statements 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 , 100 kPa). ☒N verify (what is  ?) Infobox references
Chemical compound

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.

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. There is evidence of dimerisation in the gaseous phase. 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. Two polymorphs exist: a room-temperature orthorhombic polymorph, and a high-temperature hexagonal polymorph. Both contain (SnBr2)∞ chains but the packing arrangement differs.

orthorhombic polymorphhexagonal polymorph

Preparation

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

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 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. 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 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 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.

References

  1. ^ Eckold, Pierre; Hügel, Werner; Dinnebier, Robert E.; Niewa, Rainer (2005). "Two Modifications of Tin(II) Bromide". Z. Anorg. Allg. Chem. 641 (8–9): 1467–1472. doi:10.1002/zaac.201500108.
  2. "Tin(II) bromide". pubchem.ncbi.nlm.nih.gov. Retrieved 12 December 2021.
  3. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
  4. J.L Wardell "Tin:Inorganic Chemistry" Encyclopedia of Inorganic Chemistry Ed: R Bruce King John Wiley & Sons (1994) ISBN 0-471-93620-0
  5. K. Hilpert; M. Miller; F. Ramondo (1991). "Thermochemistry of tetrabromoditin and bromoiodotin gaseous". J. Phys. Chem. 95 (19): 7261–7266. doi:10.1021/j100172a031.
  6. Abrahams I.; Demetriou D.Z. (2000). "Inert Pair Effects in Tin and Lead Dihalides: Crystal Structure of Tin(II) Bromide". Journal of Solid State Chemistry. 149 (1): 28–32. Bibcode:2000JSSCh.149...28A. 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. ^ Cotton, F. Albert; Wilkinson, Geoffrey; Murillo, Carlos A.; Bochmann, Manfred (1999), Advanced Inorganic Chemistry (6th ed.), New York: Wiley-Interscience, ISBN 0-471-19957-5
  10. Bulten E.J. (1975). "A convenient synthesis of (C1-C18) alkyltin tribromides". Journal of Organometallic Chemistry. 97 (1): 167–172. doi:10.1016/S0022-328X(00)89463-2. hdl:1874/15985.
  11. Chung Chun Hsu & R. A. Geanangel (1977). "Synthesis and studies of trimethylamine adducts with tin(II) halides". Inorg. Chem. 16 (1): 2529–2534. doi:10.1021/ic50176a022.
  12. Chung Chun Hsu & R. A. Geanangel (1980). "Donor and acceptor behavior of divalent tin compounds". Inorg. Chem. 19 (1): 110–119. doi:10.1021/ic50203a024.
Tin compounds
Sn(II)
Sn(IV)
Bromine compounds
Br(−I)
Br(−I,I)
Br(I)
Br(II)
Br(I,V)
Br(III)
Br(IV)
Br(V)
Br(VII)
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