Germanium forms several tetravalent hydrides that have the general formula GenH2n+2 similar to alkanes and silicon hydrides. The formulas and CAS Registry numbers of the three common hydrides are:
Name CAS No. Formula
Monogermane (the tetrahydride) [7782-65-2] GeH4
Digermane [13818-89-8] Ge2H6
Trigermane [14691-44-2] Ge3H8
Monogermane is used to produce high purity germanium metal. It also is used as a doping substance for electronic components.
Germanium hydrides are less stable than the corresponding hydrides of carbon and silicon. Thermal decomposition produces germanium and hydrogen. Monogermane decomposes at 350°C, while digermane and trigermane decompose to their elements at 210° and 190°C, respectively, at 200 torr. At elevated temperatures the hydrides dissociate, depositing mirror-like germanium crystals on container surfaces. Heating with oxygen yields germanium oxide. GeO2:
GeCl4 + 2O2→GeO2 + 2H2O
Polygermanes may be prepared by the reaction of magnesium germanide, Mg2Ge, with dilute hydrochloric acid in an atmosphere of hydrogen. Monogermane, GeH4, may be prepared by various methods, such as: (1) Reduction of germanium tetrachloride, GeCl4, with lithium aluminum hydride in ether, (2) Electrolysis of a solution of germanium oxide, GeO2, in sulfuric acid using lead electrodes, and (3) Reaction of magnesium germanide and ammonium bromide, NH4Br, in liquid ammonia.
Monogermane is moderately toxic. Inhalation causes irritation of the respiratory tract. Chronic exposure can induce kidney and liver damage.
Colorless gas, decomposes at 350C, insoluble in water, soluble in liquid ammonia, slightly soluble in hot hydrochloric acid.
Germane is a colorless, flammable gas.
Pungent odor.
Doping agent for solid-state electronic
components
Germanium tetrahydride (GeH4) is used to produce crystals of germanium. It is extremely
toxic.
It is used to produce high-purity germaniummetal and as a doping substance for electroniccomponents.
A germanium hydride of the general
formula GenH2n+2.
GERMANE is a colorless gas with a pungent odor.The gas is heavier than air and a flame can flash back to the source of leak very easily. GERMANE is toxic by inhalation. Prolonged exposure of the containers to fire or intense heat may result in their violent rupturing and rocketing. GERMANE is used in making electronics.
Highly flammable. Pyrophoric, the germanium hydrides are spontaneously flammable in air [Merck 1989]. Germanium has an exothermic reaction when dropped in water accompanied by crackling [Bretherick's 5th edition].
Hydrides, such as GERMANE, are reducing agents and react rapidly and dangerously with oxygen and with other oxidizing agents, even weak ones. Thus, they are likely to ignite on contact with alcohols. Hydrides are incompatible with acids, alcohols, amines, and aldehydes.
TOXIC; may be fatal if inhaled or absorbed through skin. Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite. Fire will produce irritating, corrosive and/or toxic gases. Runoff from fire control may cause pollution.
Germane is a moderately toxic gas. Itexhibits acute toxicity, lower than that ofstannane, but much greater than that ofsilane. By contrast, its poisoning effects aresomewhat similar to the group VB metalhydrides, arsine, and stibine, while beingmuch less toxic than the latter two compounds.Exposure to this gas can cause injuryto the kidney and liver. A 1-hour exposure toa concentration of 150–200 ppm in air wasfatal to test animals, including mice, guineapigs, and rabbits. Inhalation of the gas canalso cause irritation of the respiratory tract.
Flammable; may be ignited by heat, sparks or flames. May form explosive mixtures with air. Vapors from liquefied gas are initially heavier than air and spread along ground. Vapors may travel to source of ignition and flash back. Some of these materials may react violently with water. Cylinders exposed to fire may vent and release toxic and flammable gas through pressure relief devices. Containers may explode when heated. Ruptured cylinders may rocket. Runoff may create fire or explosion hazard.
Poison by inhalation.
Moderately toxic by ingestion. A hemolytic
gas. Ignites spontaneously in air.
Incompatible with Brz. See also
HYDRIDES, GERMANIUM
COMPOUNDS, and GERMANIUM.
This material is used as a doping
agent in solid state electronic component manufacture.
UN2192 Germane, Hazard Class: 2.3; Labels:
2.3-Poisonous gas, 2.1-Flammable gas, Inhalation Hazard
Zone B. Cylinders must be transported in a secure upright
position, in a well-ventilated truck. Protect cylinder and
labels from physical damage. The owner of the compressed
gas cylinder is the only entity allowed by federal law
(49CFR) to transport and refill them. It is a violation of
transportation regulations to refill compressed gas cylinders
without the express written permission of the owner.
Pyrophoric; may ignite spontaneously in
air. Attacks hydrocarbon and fluorocarbon lubricants.
Incompatible with oxidizers (chlorates, nitrates, peroxides,
permanganates, perchlorates, chlorine, bromine, fluorine,
etc.); contact may cause fires or explosions. Keep away
from oxidizing and nonoxidizing acids, ammonia, aqua
regia, sulfuric acid, carbonates, halogens, and nitrates.
Explosive reaction or ignition with potassium chlorate,
potassium nitrate, chlorine, bromine, oxygen, and potas sium hydroxide in the presence of heat.
The initial threshold screening level (ITSL) for germane (germanium tetrahydride) is 6 μg/m3 based on an 8 hour averaging time.
Return refillable compressed
gas cylinders to supplier. Dispose of contents and container
to an approved waste disposal plant. All federal, state, and
local environmental regulations must be observed.
