Thermochemistry of metallic alkyls. Part 10.—Heats of combustion of some tetra-alkyls of tin

Abstract

The heats of combustion at 25°C of liquid SnMe4, SnMe3Et and SnEk, SnPr4 and SnBw have been measured using a conventional bomb calorimeter charged with 0 2 at 40 atm pressure. Corrections for incomplete combustion of the samples were based on analysis of the C02 produced by combustion, and of unburnt metallic tin remaining in the crucible. The derived standard heats of formation of the liquids at 25°C are (in kcal/mole) AH; (SnMe4) = -125 f0.5 ; AH; (SnMe3Et) = -161 f0.6 ; AHj!(SnEt4) = -22.9*06 ; AH;(SnPr4) = -50.6f1.2; AHi(SnBu4) = -72-7hl.8. The values now obtained for AHF(SnMe4) and AHj!(SnBu4), combined with previously measured heats of haIogenation of tin alkyls, provide standard heats of formation of the following liquids (in kcal/mole) ; Me3SnBr = -43.8L-1-6; Me3SnI = -30-7kl.7; Me3SnPh = 13-6f2.6 ; Me3SnCHzPh = 6 -7 5 1.7 ; 13.2f 1.7 ; Me3SnSnMe3 = -17.4 f 3-3 ; Me3Sn vinyl = and Bu3SnBr = -85.5f2.The few heat of formation data on tin alkyls so far reported are not in good agreement with one another. Heat of combustion studies on tin tetra-alkyls are limited to those reported by Jones, Evans, Gulwell and Griffiths 1 on SnEt4, SnPr4, SnBu4 and SnAm4, by Lippincott and Tobin 2 on SnMe4, by Lautsch 3 and also by Baladin, Klabunorskii, Kozina and Ul'yanova 4 on SnMe4 and SnEt4, by Dillard, McNeill, Simmons and Yeldwell5 on SnMe4, SnMe3Et, SnMeeEt2, SnMeEt3, SnEt4, SnEt2Bu2 and SnBu4, and by Rabinovich, Telnoi, Nikolaev and Razuvaev 6 on SnEt4.Jones et aZ.1 gave no details of their experimental procedure ; it is now clear that their results were unreliable. Dillard, McNeill, Simmons and Yeldell5 also give few details of the combustion experiments, but they have estimated the limits of error ; there is, however, a lack of internal consistency in the results, and it is difficult to accept that the quoted error limits (which range from & I to & 5 kcal/mole) are realistic. Lippincott and Tobin2 measured the heat of combustion of SnMe4, and observed that the metal sometimes did not bum completely to form Sn02, and that the oxide product formed in the crucible was blackened by traces of unburnt tin. Because of this, the results of individual combustion experiments showed a considerable scatter, and their recommended value for the standard heat AH," of combustion was stated to be uncertain within limits of f 10 kcallmole.The combustion studies by Lautsch,3 by Baladin et aZ.,4 and by Rabinovich et aZ.,6 on SnMe4 and SnEt4, appear to have given more consistent results, and an accuracy within limits of + 3 to +4 kcallmole was claimed. The -AH: values (kcal/mole) for tin tetra-alkyls in the liquid state obtained by previous investigators are listed below.* This was replaced in some experiments by a silica crucible coated with a layer of stannic oxide. This made no significant difference to the measured heats of combustion, indicating that reaction between SnO2 and the silica crucible is not a serious complication.

Heats of combustion of four dialkylethers

“…1002) and calorimetric assembly of similar design to that described by Prosen and Rossini.6 isoPropylether was studied at Manchester, using a bomb calorimeter system previously described. 7 The starting (firing) temperature was 25°C in both sets of experiments. the sealed ampoule.…”

Computational Thermochemistry of Mono- and Dinuclear Tin Alkyls Used in Vapor Deposition Processes

“…Our calculated value of 169.1 kJ/mol is reasonably close to this value. There are several studies related to the enthalpy of formation of Me 4 Sn, ,, although according to Dávalos et al, they rely on the enthalpy of formation of liquid tetramethyltin (Δ H ° f = −52.3 ± 1.9 kJ/mol) established by Davies et al in 1963 . Dávalos et al recently corrected this liquid value to −49.2 ± 1.9 kJ/mol .…”

Thermochemistry of metallic alkyls. Part 12.—Heat of combustion of tetraethyl germanium and of tetrapropyl germanium

“…The bomb calorimeter, and the general combustion procedure, have been described previously. 5 The combustion samples, sealed in Melinex polyester bags, were supported in the silica crucible in the bomb charged with 0 2 at 40atm pressure, and ignited at 25OC. Combustion was usually satisfactory, leaving no traces of soot on bomb walls or fittings.…”