Thallide

Not to be confused with Thalidomide.

Thallides are compounds containing anions composed of thallium. Thallium may occur as a monatomic ion (Tl⁵⁻ in LiMg₂Tl), as a cluster of several atoms (e.g. Tl₄⁸⁻), or as a polyatomic structure Tl_nⁿ⁻ in thallides.^[4][5][6] They are a subclass of trielides,^[6] which also includes gallides and indides.^[7] A more general classification is polar intermetallics, as clusters contain delocalized multicentre bonds.^[8] Thallides were discovered by Eduard Zintl in 1932.^[9]

Thallide^[1][2][3]

Example thallide monoclinic Cs_7.29K_5.71Tl₁₃ containing [Tl₆]⁶⁻ and [Tl₇]⁷⁻ clusters

Mixed anion compounds with thallides include halides (bromides and chlorides),^[10] oxides,^[11] and tetrelates (silicate, germanate).^[12]

Production

Thallide compounds can be produced by melting metals together in a tantalum crucible under an inert argon atmosphere.^[7] However if arsenic is included in the mix, it can react with the crucible wall.^[13]

A low temperature production route, is to dissolve an alkali metal in liquid ammonia, and use that to reduce a thallium salt, like thallium iodide.^[14]

Properties

Thallide compounds are dense, dense to X-rays and usually metallic grey or black in appearance.

Thallide clusters mostly do not follow Wade-Mingos rules or the Zintl–Klemm concept, as they have too small a negative charge. They can be called "hypoelectronic".^[15]

Reactions

In liquid ammonia, oxidation occurs yielding metal amides, and thallium metal.^[6]

Thallides react with water and air.^[6]

List

formula	system	space group	unit cell	volume	density	comment	ref
LiTl	cubic	Pm3m	a=3.43			melts at 508 °C	[16]
Li2Tl	orthorhombic	Cmcm	a=4.741 b=10.023 c=4.786			decomposes at 381 °C	[9][16]
Li5Tl2		R3m	a=4.716 c=20.399			melts at 448 °C	[9][16]
Li3Tl	cubic	Fm3m	a=6.67			melts at 447 °C	[9][16]
Li22Tl5 (Li4Tl)	cubic	F43m	a=20.003				[9][16]
NaTl	cubic	Fd3m				3D diamond structure mesh for Tl; melts at 305 °C	[6][14][16]
NaTl	tetragonal	I41/amd	a=5.2341 c=7.5290 Z=4	206.26		grey;	[14][16]
Na2Tl	orthorhombic	C2221	a=13.9350 b=8.8797 c=11.6927			[Tl4]8– tetrahedra; melts at 154 °C	[6][16]
NaTl2						decomposes at 154 °C	[16]
Na6Tl	cubic	F43m	a=24.154			melts at 77.4	[16]
KTl	orthorhombic	Cmca	a=15.239 b=15.069 c=8.137			[Tl6]6– Compressed octahedra; melts incongruently at 268 °C	[6][16]
K5Tl8						melts at 273 °C	[16]
K10Tl7	monoclinic	P21/c	a = 10.132 b = 22.323 c = 13.376 β = 93.14° Z=4			[Tl7]7– pentagonal bipyramid	[6]
K10Tl6O2						[Tl6]6–	[6]
K8Tl11	rhombohedral	R3c	a=9.991 c=5.084			[Tl11]7– pentacapped trigonal prism; melts at 320 °C	[6][16]
K49Tl108		Pm3	a = 17.28.7 Z=1				[17]
K5Tl17	orthorhombic	Cccm					[9]
K6Tl17	orthorhombic	Cccm	a = 16.625 b = 23.594 c = 15.369 Z = 8	6028	8.173	@22 °C; metallic; ρ270 = 22.6 μΩ·cm, α = 0.0023 K−1	[18]
K10Tl6O2	orthorhombic	Cmcm	a=8.3755 b=32.102 c=8.8634 Z=4	2383.1	4.597	dark grey	[11]
Na7KTl4	orthorhombic	Pbam	a=16.2860 c=11.2771 Z=8	2991.1	4.519	[Tr4]8−	[19]
Na9K16Tl~25							[6]
[Et4N]2[{Tl(Fe(CO)4)2}2]							[20]
[(PPh2)2N]2[Tl2Fe6(CO)24]	monoclinic	P21/c	a=17.120 b=50.71 c=16.785 β=116.90°				[20]
[Et4N]4[Tl4Fe8(CO)30]							[20]
[Et4N]6[Tl6Fe10(CO)36]							[20]
K8ZnTl10						band gap 0.17 eV	[7]
K8GaTl10	tetragonal	P4/nnc	a=10.1858 c=13.6371 Z=2	1414.9	5.695		[7]
K49Ga2Tl108							[7]
Rb8Tl11						[Tl11]7– pentacapped trigonal prism	[6]
Rb15Tl27		P62m					[21]
Rb17Tl41	hexagonal	Fd3m	a = 10.3248 c = 17.558				[9]
Rb10Tl6O2	orthorhombic	Cmcm	a=8.7176 b=33.2934 = 9.1242	2648.19	5.300	dark grey; [Tl6]6–	[6][11]
Na7RbTl4	orthorhombic	Pbam	a=16.3584 b=16.3581 c=11.3345 Z=8	3033.0	4.660	@123K [Tl4]8− tetrahedra	[22]
K4Rb4Tl11Cl0.1	rhombohedral	R3c	a=10.0948 c=51.027 Z=6	4503.3	6.087		[10]
Rb8GaTl10	tetragonal	P4/nnc	a=10.4714 c=14.0007 Z=2	1535.2	6.051		[21]
Rb49Ga2Tl108							[7]
Sr3Tl5	orthorhombic	Cmcm	a = 10.604 b = 8.675 c = 10.985 Z = 4	1010.5	8.445	silvery, brittle; [Tl5]6– square pyramidal clusters	[8]
YMgTl	hexagonal	P62m	a=7.505 c=4.5985 Z=3		7.05	metallic; black powder	[23]
Pd3Tl	tetragonal	I4/mmm	a=4.10659 c=15.3028 Z = 4	258.07		Palladothallite	[24]
SrPdTl2	orthorhombic	Cmcm	a = 4.486 b = 10.991 c = 8.154 Z = 4				[25]
Na13(Cd~0.70Tl~0.30)27	cubic	Im3	a ≃ 15.92 Z = 4			Tl from 0.24 to 0.33	[26]
K14Cd9Tl21	hexagonal	P2m	a = 9.884 c =17.173 Z = 2				[27]
Na9K16Tl18Cd3	hexagonal	P63/mmc	a = 11.136 c = 29.352 Z=2				[28]
Rb5Cd2Tl11	orthorhombic	Amm2	a = 5.5999 b = 17.603 c = 12.896 Z = 2				[29]
Na12K18In53Tl7		R3m	a=16.846 c=43.339 Z=4				[30]
Na6TlSb4	monoclinic	C2/c	15.154 b = 10.401 c = 17.413 β = 113.57° Z = 8			metallic	[31]
K6Tl2Sb3	monoclinic	C2/c	a = 9.951 b = 17.137 c = 19.640 β = 104.26° Z = 8				[31][32]
CsTl	orthorhombic	Fddd				[Tl6]6–	[6]
Cs3.45K3.55Tl7	tetragonal	I41/a	a = 13.6177 c = 25.5573 Z = 8	4739.3	5.681	[Tl7]7−	[6]
Cs7.29K5.71Tl13	monoclinic	C2/c	a = 30.7792 b = 11.000 c = 14.0291 β = 112.676° Z = 4	4382.7	5.835	[Tl7]7− and [Tl6]6–	[6]
K3.826Cs4.174Tl11							[6]
Cs8Tl11						[Tl11]7– pentacapped trigonal prism	[6]
Cs15Tl27	hexagonal	P62m					[9][21]
Cs4Tl2O	trigonal	R3m	a = 11.986 c = 20.370 Z = 9	2534.3	5.640	silvery black; stable to 523 °C; decomposes in air	[33]
Cs18Tl8O6							[33]
Cs10Tl6SiO4	monoclinic	P21/c	a=18.9121 b=11.4386 c=14.8081 β=90.029°			[Tl6]6–	[6][12]
Cs10Tl6GeO4	monoclinic	P21/c	a=19.034 b=11.4883 c=14.8633 β=90.033°			[Tl6]6–	[6][12]
Cs10Tl6SnO3	orthorhombic	Pnma	a=14.8908Å b=19.052 c=11.5855			[Tl6]6–	[6][12]
Rb14CsTl27	hexagonal						[21]
Cs8GaTl10	tetragonal	P4/nnc	a=10.777 c=14.354 Z=2	1667.3	6.328		[7]
Cs5Cd2Tl11	orthorhombic	Amm2	a = 5.6107 b = 18.090 c = 13.203 Z = 2				[29]
Cs8Tl11Pd0.84	rhombohedral	R3c	a = 10.6l0 c = 54.683 Z = 6				[34]
Cs8Tl11Cl0.8	rhombohedral	R3c	a=10.4691 c=53.297 Z = 6	5058.8	6.578		[10]
Cs8Tl11Br0.9	rhombohedral	R3c	a=10.5608 c=53.401 Z = 6	5157.9	6.539		[10]
Cs5Rb3Tl11Cl0.5	rhombohedral	R3c	a=10.3791 c=52.437 Z = 6	4892.0	6.502		[10]
Cs5.7K2.3Tl11Cl0.6	rhombohedral	R3c	a=10.3291 c=51.909 Z = 6	4796.3	6.469		[10]
BaTl2	hexagonal	P63/mmc					[35]
BaTl4	monoclinic	C2/m	a = 12.408 b = 5.351 c = 10.383 β = 116.00° Z = 4	519.6		silvery	[36]
LaMgTl	hexagonal	P62m	a=7.813 c=4.7784 Z=3		7.25	metallic; black powder	[23]
CeMgTl	hexagonal	P62m	a=7.741 c=4.7375 Z=3		7.47	metallic; black powder	[23]
PrMgTl	hexagonal	P62m	a=7.702 c=4.7150 Z=3	242.9	7.60	metallic; black powder	[23]
NdMgTl	hexagonal	P62m	a=7.666 c=4.6945 Z=3	242.9	7.74	metallic; black powder	[23]
SmMgTl	hexagonal	P62m	a=7.603 c=4.6593 Z=3		8.10	metallic; black powder	[23]
EuTl2							[37]
EuPdTl2	orthorhombic	Cmcm	a=4.466 b=10.767 c=8.120 Z=4	3905	11.35	silvery metallic	[37]
GdMgTl	hexagonal	P62m	a=7.556 c=4.6312 Z=3	229.9	7.74	metallic; black powder	[23]
TbMgTl	hexagonal	P62m	a=7.518 c=4.6088 Z=3	226.7	8.52	metallic; black powder	[23]
DyMgTl	hexagonal	P62m	a=7.495 c=4.5932 Z=3	224.1	8.69	metallic; black powder	[23]
HoMgTl	hexagonal	P62m	a=7.471 c=4.5835 Z=3			metallic; black powder	[23]
ErMgTl	hexagonal	P62m	a=7.449 c=4.5715 Z=3			metallic; black powder	[23]
TmMgTl	hexagonal	P62m	a=7.432 c=4.5541 Z=3			metallic; black powder	[23]
LuMgTl	hexagonal	P62m	a=7.402 c=4.5400 Z=3			metallic; black powder	[23]
K5TaAs4Tl2	orthorhombic	Pnma					[38]
Rb5TaAs4Tl2	orthorhombic	Pnma	a = 19.196 b = 11.104 c = 7.894 Z = 4			spiro at Ta	[38]
SrPtTl2	orthorhombic	Cmcm	a = 4.491 b = 10.990 c = 8.140 Z = 4				[25]
Na12K38Tl48Au2						Tl7 and Tl9 cluster + auride	[6]
K3Au5Tl	orthorhombic	Imma	a = 5.595 b =19.706 c =8.430 Z = 4				[13]
Rb2Au3Tl	orthorhombic	Pmma	a = 5.660 b = 6.741 c = 9.045 Z = 4				[13]
BaAuTl3	tetragonal	I4/mmm	a = 4.8604 c = 12.180 Z = 2				[39]
Ba2AuTl7	orthorhombic	Pmma	a=21.919 b=5.193 c=10.447				[40]
BaAu0.40Tl1.60	orthorhombic	Imma	a = 5.140 b = 8.317 c = 8.809 Z = 4				[35]
BaHg0.80Tl3.20	monoclinic	C2/m	a=12.230 b=5.234 c=10.379 β = 115.272	600.3	10.523	silvery	[36]