元素英文

13

Arnic,AntimonyandBismuth

13.1Introduction

Thethreeelementsarnic,antimonyand

bismuth,whichcompleteGroup15oftheperiodic

table,wereamongsttheearliestelementstobe

isolatedandallwereknownbeforeeithernitrogen

(1772)orphosphorus(1669)hadbeenobtained

pertiesofarnic

sulfideandrelatedcompoundshavebeenknown

tophysiciansandprofessionalpoisonerssincethe

fifthcenturyBCthoughtheiruisnolonger

recommendedbyeithergroupofpractitioners.

Isolationoftheelementissometimescredited

toAlbertusMagnus(AD1193-1280)whoheated

orpiment(AS&)withsoap,anditsname

reflectsitsancientlineage.[Arnic,Latin

arnicumfromGreek&~~VLK~V(arnicon)

whichwasitlfderived(withadditionof6v)

fromPersianaz-zarnTkh,yelloworpiment(zar=

gold).]Antimonycompoundswerealsoknown

totheancientsandtheblacksulfide,stibnite,was

udinearlybiblicaltimesasacosmetictodarken

andbeautifywomen’yebrows;arareChaldean

vaofcastantimonydatesfrom4000BCand

antimony-coatedcopperarticleswereudin

(-AD50)gaveit

thenamestibiumandwritingsattributedtoJabir

(-AD800)udtheformantimonium;indeed,

bothnameswereudforboththeelement

anditssulfideuntiltheendoftheeighteenth

century(Lavoisier).Thehistoryoftheelement,

likethatofarnic,ismuchobscuredbythe

intentionallyvagueandmisleadingdescriptions

ofthealchemists,thoughtheelusiveBenedictine

monkBasilValentinemayhaveprepareditin

1492(aboutthetimeofColumbus).

publishedhisfamousTreationAntimonyin

hwasknownasthemetalat

leastby1480thoughitsprevioushistoryin

theMiddleAgesisdifficulttounravelbecau

theelementwassometimesconfudwithPb,

Sn,enbergprinting

press(1440onwards)udtypethathadbeen

cutfrombrassorcastfromPb,SnorCu,

butabout1450acretmethodofcasting

typefromBialloyscameintouandthis

particularuisstillanimportantapplicationof

theelement(p.549).Thenamederivesfromthe

GermanWismut(possiblywhitemetalormeadow

mines)andthiswaslatinizedtobimutumby

(Agricola)ethedifficultyof

541

548Arnic,AntimonyandBismuthCh.73

ElementSnEuBeAsTaGe

PPM2.12.12.01.81.71.5

Order48=48=50515253

assigningprecidatestodiscoveriesmadeby

alchemists,minersandmetalworkers(orindeed

evendiscerningwhatthodiscoveriesactually

were),itemsclearthatAs,SbandBibecame

increasinglyrecognizedintheirfreeformduring

thethirteenthtofifteenthcenturies;theyare

thereforecontemporarywithZnandCo,and

predateallotherelementxceptthe7metals

and2non-metallicelementsknownfromancient

times(Au,Ag,Cu,Fe,Hg,Pb,Sn;CandS).'')

Arnicandantimonyareclasdasmetalloids

ormi-metalsandbismuthisatypicalBsub-

group(post-transition-element)metalliketinand

lead.

InSbCdPdPtBiOsAu

0.240.20.160.0150.010.0080.0050.004

67071

13.2TheElements

ance,distribution

andextraction

Noneofthethreeelementsisparticularlyabun-

dantintheearth'scrustthoughveralminerals

e

enfromTable13.1,arnicoccursabouthalf-

waydowntheelementsinorderofabundance,

-

monyhasonlyone-tenthofthisabundanceand

Bi,downbyafurtherfactorof20ormore,is

aboutasunabundantasveralofthecommoner

onwithallthe

post-transition-elementmetals,As,SbandBiare

chalcophiles,curinassociationwith

thechalcogensS,SeandTeratherthanasoxides

andsilicates.

Arnicmineralsarewidelydistributed

throughouttheworldandsmallamountsofthe

',DiscoveryoftheElements,Chap.3,

pp.91-119,JournalofChemicalEducation,Easton,Pa,

1956.

mineralsincludethetwosulfidesrealgar(AsqS4)

andorpiment(As&)andtheoxidizedform

arnolite(As203).ThearnidesofFe,Coand

Niandthemixedsulfideswiththemetals

formanothertofminerals,ng-

ite(FeAs2),safforlite(CoAs),niccolite(NiAs),

rammelsbergite(NiAs2),arnopyrite(FeAsS),

cobaltite(CoAsS),enargite(CU~ASS~),gersdorf-

fite(NiAsS)andthequaternarysulfideglaucodot

[(Co,Fe)AsS].ElementalAsisobtainedonan

industrialscalebysmeltingFeAs2orFeAsS

at650-700°Cintheabnceofairand

condensingthesublimedelement:FeAsS--+

FeS+As&)---+As(s).ResidualAstrappedin

thesulfideresiduescanbereleadbyroasting

theminairandtrappingthesublimedAs203in

decantheneitherbeud

directlyforchemicalproductsorreducedwith

charcoalat700-800"203is

alsoobtainedinlargequantitiesasfluedustfrom

thesmeltingofCuandPbconcentrates;becau

ofthehugescaleoftheoperations(pp.1174,

371)thisreprentsthemostimportantindustrial

oductionfiguresandmajor

usofAsanditscompoundsarelistedinthe

Panel.

Stibnite,Sb2S3,isthemostimportant

oreofantimonyanditoccursinlarge

quantitiesinChina,SouthAfrica,Mexico,

ulfideoresinclude

ullmanite(NiSbS),livingstonite(HgSb4S8),

tetrahedrite(Cu3SbS3),wolfsbergite(CuSbSz)

andjamesonite(FePb4Sb6S14).Indeed,complex

orescontainingPb,Cu,AgandHgarean

mounts

ofoxidemineralsformedbyweatheringare

alsoknown,inite(Sb203),cervantite

(SbzOd),andstibiconite(Sb204.H2O),and

minorfindsofnativeSbhaveoccasionally

cialoreshave5-60%

Sb,andrecoverymethodsdependonthe

513.2.1

Abundance,distributionandextraction

549

-gradesulfideores(5-2596Sb)are

volatilizedastheoxide(anyAs203beingreadily

removedfirstbyvirtueofitsgreatervolatility).

Theoxidecanbereducedtothemetalby

heatingitinareverberatoryfurnacewithcharcoal

intheprenceofanalkalimetalcarbonate

Kirk-OthmerEncyclopediaofChemicalTechnology,4th

edn.,Vol.3,Wiley,NewYork,1992;Arnicandarnic

alloys(pp.624-33);Arniccompounds(633-59);Anti-

monyandantimonyalloys(367-81);Antimonycom-

pounds(382-412);Bismuthandbismuthalloys(Vol.4,1992

(pp.237-45);Bismuthcompounds(246-70).

ediateores(25-40%)

aresmelted

inablastfurnaceandtheoxide

ntaining

40-60%Sbareliquatedat550-600"under

reducingconditionstogiveSb2S3andthen

treatedwithscrapirontoremovethesulfide:

Sb2.53+3Fe-2Sb+mplex

sulfideoresaretreatedbyleachingandelectro-

winning,ctrolysisofalkalinesolutions

ofthethioantimonateNa3SbS4,andtheelement

isalsorecoveredfromthefluedustsofPb

SbcontainsPb,As,S,Feand

550Arnic,AntimonyandBismufhCh.13

Cu;thelattertwocanberemovedbystibnite

treatmentorheatingwithcharcoaVNa2S04flux;

theAsandScanberemovedbyanoxidizingflux

ofNaN03andNaOH(orNa2C03);Pbishardto

removebutthisisunnecessaryiftheSbistobe

udinPballoys(ebelow).Electrolysisyields

>99.9%purityandremainingimpuritiescanbe

scaleofproductionandthevarioususofSb

anditscompoundsaresummarizedinthePanel.

Bismuthoccursmainlyasbismite(a-Bi203),

bismuthinite(Bi2S3)andbismutite[(BiO)2CO,];

veryoccasionallyitoccursnative,inassociation

withPb,ncommercial

sourceoftheelementisasabyproductfrom

PbtZnandCuplants,fromwhichitisobtained

byspecialprocessdependentonthenatureof

themainproduct.(')Sulfideoresareroastedto

theoxideandthenreducedbyironorcharcoal.

Becauofitslowmp,verylowsolubilityinFe,

andfairlyhighoxidativestabilityinair,Bican

bemeltedandcast(likePb)inironandsteel

,themetalistoobrittletoroll,

draw,orextrudeatroomtemperature,butabove

225°CBicanbeworkedquitewell.

13.2.2Atomicandphysicalproperties

ArnicandBi(likeP)eachhaveonly1stable

isotopeandthisoccurswith

100%abundancein

ingly

(p.17)theiratomicweightsareknownwithgreat

precision(Table13.2).Antimonyhas2stable

isotopes(likeN);however,unlikeN,whichhas1

predominantlyabundantisotope,the2isotopesof

Sbareapproximatelyequalinabundance(12'Sb

57.21%,123Sb42.79%)andconquently(p.17)

theatomicweightisknownwithsomewhatless

accuracy.

Itisalsonoteworthythat209Biis

theheavieststableisotopeofanyelement;all

nuclidesbeyond':Biareradioactive.

Theground-stateelectronicconfigurationof

eachelementinthegroupisns2np3withan

unpairedelectronineachofthethreeporbitals,

andmuchofthechemistryofthegroupcan

r,

smoothtrendsaresometimesmodified(oreven

abntaltogether),firstly,becauofthelack

oflow-lyingemptydorbitalsinN,which

differentiatesitfromitsheaviercongeners,and,

condly,becauofthecountervailinginfluence

oftheunderlyingfilleddandforbitalsinAs,

rturbationsareapparentwhen

thevariousionizationenergiesinTable13.2

areplottedasafunctionofatomicnumber.

Table13.2alsocontainsapproximatedataon

theconventionalcovalentsingle-bondradiifor

threefoldcoordinationthoughthevaluesvary

byaboutf4pminvarioustabulationsandshould

6-coordinate

"effectiveionicradii"forthe+3and+5

Table13.2AtomicpropertiesofGroup15elements

PropertyNPAsSbBi

Atomicnumber

Atomicweight(1997)

Electronicconfiguration

Ionizationenergies/MJmol-'(I)

(11)

(111)

Sum(I+II+III)/MJmol-'

Sum(IV+V)/MJmol-'

Electronegativityx

r,,,(M"'singlebond)/pm

riOnlc(6-coordinate)(M"')/pm

(6-coordinate)(MV)/pm

71533

14.00674(7)30.973762(4)74.92160(2)

[He12s22p3[Ne]3s23p3[Ar13d'04s24p3

1.402

2.856

4.577

8.835

16.920

3.O

70

(16)

(13)

1.012

1.903

2.910

5.825

11.220

2.1

110

44

38

0.947

1.798

2.736

5.481

10.880

2.0

120

58

46

51

121.760(1)

[Kr]4di05s25p3

0.834

1.595

2.443

4.872

9.636

1.9

140

76

60

83

208.98038(2)

[Xe]4fi45d"-

6s26p3

0.703

1.610

2.466

4.779

9.776

1.9

150

103

76

813.2.2Atomicandphysicalproperties551

n's

tab~lation,(~)butshouldnotbetakentoimplythe

prenceofM3+andM5+cationsinmanyofthe

compoundsoftheelements.

Arnic,SbandBieachexistinveral

allotropicform~(~3~)thoughtheallotropyisnot

soextensiveasinP(p.481).Therearethree

crystallineformsofAs,ofwhichtheordinary,

grey,"metallic",rhombohedral,a-formisthe

istsof

puckeredsheetsofcovalentlybondedAsstacked

inlayersperpendiculartothehexagonale-axis

eachlayereach

Ashas3nearestneighboursat251.7pmand

theangleAs-As-Asis96.7';eachAsalso

hasafurther3neighboursat312pminan

-formsofSbandBiare

isostructuralwitha-Asandhavethedimensions

eenthatthereisa

progressivediminutioninthedifferencebetween

intra-layerandinter-layerdistancesthoughthe

inter-bondanglesremainalmostconstant.

Figure13.1

PuckeredlayerstructureofAsshowing

pyramidalcoordinationofeachAsto

3neighboursatadistanceij(252pm).

ThedispositionofAsatomsinthenext

layer(r2312pm)isshownbydashed

lines.

N,ActaCryst.A32,751-67(1976).

E,TheStructureoftheElements,Wiley,1974,

NERING,.20,

436pp.

33-51(1981).

Table13.3ComparisonofblackPanda-rhombohe-

dralAs,SbandBi

rl/pmr2/pmr2/r1iM-M-M

BlackP223.1(av)332.4(av)1.4902at96.3"

(1at102.17

a-As251.7312.01.24096.7"

a-Sb290.8335.51.15396.6"

a-Bi307.2352.91.14995.5"

InthevapourphaAsisknowntoexist

astetrahedralAs4moleculeswith(As-As

243.5pm)andwhentheelementissublimed,

ayellow,cubicmodificationisobtainedwhich

probablyalsocontainsAs4unitsthoughthe

structurehasnotyetbeendeterminedbecau

mineralarnolampriteisanotherpolymorph,E-

As;itispossiblyisostructuralwith"metallic"

orthorhombicP.

Antimonyexistsin5formsinadditiontothe

ordinarya-formwhichhasbeendiscusdabove.

Theyellowformisunstableabove-90";ablack

formcanbeobtainedbycoolinggaousSb,and

anexplosive(impure?)formcanbemadeelec-

remainingcrystallineforms

aremadebyhigh-pressuretechniques:FormI

hasaprimitivecubiclatticewitha0296.6pm:

itisobtainedfroma-Sbat50kbar(SGPa,Le.

5xlo9Nm-2)byincreasingtherhombohedral

anglefrom57.1"to60.0"togetherwithsmall

shiftsinatomicposition

sothateachSbhas6

rincreainpres-

sureto90kbaryieldsFormI1whichishcpwith

aninteratomicdistanceof328pmforthe12near-

estneighbours.

SeveralpolymorphsofBihavebeendescribed

butthereisasyetnogeneralagreementontheir

structurexceptfora-Bi(above)and<-Siwhich

formsat90kbarandhasabccstructurewith8

nearestneighboursat329.1pm.

Thephysicalpropertiesofthea-rhombohedral

formofAs,SbandBiaresummarizedin

rN2andP4areincludedfor

llineAsisrathervolatileand

thevapourpressureofthesolidreaches1atm

at615"some200"belowitsmpof816°C(at

38.6atm,i.e.3.91MPa).AntimonyandBiare

552Arnic,AntimonyandBismuthCh.73

Table13.4SomephysicalpropertiesofGroup15elements

PropertyN2P4WASa-Sba-Bi

MPPC-210.044.1816(38.6atm)630.7271.4

BPPC-195.8280.5615(subl)17531564

Density(25T)/gcm-30.879(-210")1.8235.778(")6.6849.808

Hardness(Mohs)--3.53-3.52.5

Electricalresistivity(20"C)/pohmcm__-33.341.7120

Contractiononfreezing/%____100.8-3.32

(a)YellowAs4hasd251,97g~m-~;encebetweenthedensityofrhombohedralblackP(3.56g~m-~)andwhiteP4

(1.823g~m-~)(p.479).

muchlessvolatileandalsohaveappreciably

lowermpsthanAs,sothatbothhavequitelong

liquidrangesatatmosphericpressure.

Arnicformsbrittlesteel-greycrystalsof

r,itslackof

ductilityandcomparativelyhighelectrical

resistivity(33.3pohmcm),coupledwithits

amphoterismandintermediatechemicalnature

betweenthatofmetalsandnon-metals,haveled

toitsbeingclassifiedasametalloidratherthan

a"true"nyisalsoverybrittle

andformsbluish-white,flaky,lustrouscrystalsof

highelectricalresistivity(41.7pohmcm).The

valuesofresistivitycanbecomparedwiththo

for"good"metalssuchasAg(1.59),Cu(1.72),

andA1(2.82pohmcm),andwith"poor"metals

suchasSn(11.5)andPb(22pohmcm).Bismuth

hasastillhigherresistivity(120pohmcm)which

evenexceedsthatofcommercialresistorssuch

asNichromealloy(l00pohmcm).Bismuthis

abrittle,white,crystallinemetalwithapinkish

emostdiamagneticofallmetals

(masssusceptibility17.0xm3kg-'-to

convertthisSIvaluetocgsmultiplyby1O3/4nt,

i.e.1.35xcm3g-').Italsohasthehighest

Halleffectcoefficientofanymetalandisunusual

inexpandingonsolidifyingfromthemelt,a

propertywhichitholdsuniquelywithGaand

Geamongtheelements.

13.2.3Chemicalreactivityandgroup

trends

Arnicisstableindryairbutthesurface

oxidizesinmoistairtogiveasuperficialgolden

bronzetarnishwhichdeepenstoablacksurface

atedinair

itsublimesandoxidizestoAs406withagarlic

likeodour(poisonous).Above250-300"the

reactionisaccompaniedbyphosphorescence(cf.

P4,p.473).Whenignitedinoxygen,Asburns

givearnides(p.554),fluorineenflamestogive

AsF5(p.561),andtheotherhalogensyieldAsX3

(p.559).Arnicisnotreadilyattackedbywater,

alkalinesolutionsornon-oxidizingacids,but

diluteHNO3givesarniousacid(H3As03).hot

concHNO3yieldsarnicacid(H~AsO~),andhot

onwithfud

NaOHliberatesH2:

As+3NaOH-+Na3As03+iH2

OneimportantpropertywhichAshasincommon

withitsneighbouringelementsimmediatelyfol-

lowingthe3dtransitionries(,As,Se,

Br)andwhichdifferentiatesitfromitsGroup15

neighboursPandSb,isitsnotablereluctanceto

beoxidizedtothegroupvalenceof+-

quentlyAs4010andH3As04areoxidizingagents

andarnatesareudforthispurpointitrimet-

ricanalysis(p.577).

Theground-stateelectronicstructureofAs,

aswithallGroup

15elementsfeatures3

unpairedelectronsns2np3;thereisasubstantial

electronaffinityfortheacquisitionof1

electronbutfurtheradditionsmustbeeffected

againstconsiderablecoulombicrepulsion,and

theformationofAs3-ishighlyendothermic.

Consistentwiththisthereareno"ionic"

compoundscontainingthearnideionand

$73.2.3Chemicalreactivityandgrouptrends553

compoundssuchasNasAsareintermetallic

r,despitethemetalloidal

characterofthefreeelement,theionization

energiesandelectronegativityofAsaresimilar

tothoofP(Table13.2)andtheelement

readilyformsstrongcovalentbondstomost

X3(X=H,hal,R,Ar

etc.)arecovalentmoleculeslikePX3and

thetertiaryarsineshavebeenwidelyudas

ligandstob-classtransitionelements(p.909).(@

Similarly,As406andAs4010rembletheir

Panaloguesinstructure;thesulfidesarealso

covalentheterocyclicmoleculesthoughtheir

stoichiometryandstructuredifferfromtho

ofP.

AntimonyisinmanywayssimilartoAs,but

abletoairand

moistureatroomtemperature,oxidizesonbeing

heatedundercontrolledconditionstogiveSb2-

03,Sb204orSbzOs,reactsvigorouslywithC12

andmoredatelywithBr2and12togiveSbX3,

andalsocombineswithSonbeingheated.H2

iswithoutdirectreactionandSbH3(p.557)is

bothverypoisonousandthermallyveryunstable.

DiluteacidshavenoeffectonSb;concentrated

oxidizingacidsreactreadily,O3

giveshydratedSb2O5,aquaregiagivesasolu-

tionofSbCl5,andhotconcH2SO4givesthesalt

Sb2(S04)3.

Bismuthcontinuesthetrendtoelectropositive

behaviourandBiz03isdefinitelybasic,

comparedwiththeamphotericoxidesofSband

isalsoagrowingtendencytoformsaltsof

oxoacidsbyreactionofeitherthemetalorits

oxidewiththeacid,~(S04)3andBi(N03)3.

DirectreactionofBiwith02,SandX2at

elevatedtemperaturesyieldsBi2O3,Bi2S3and

BiX3respectively,buttheincreasingsizeofthe

metalatomresultsinasteadydecreainthe

strengthofcovalentlinkagesinthequence

P>As>Sb>mostnoticeableinthe

instabilityofBiH3andofmanyorganobismuth

compounds(p.

599).

FFE(ed.),TransitionMetalComplexesof

Phosphorus,ArnicandAntimonyLigands,Macmillan,

London,1973,428pp.

Mostofthetrendsarequalitativelyunderstand-

ableintermsofthegeneralatomicpropertiesin

Table13.2thoughtheyarenotreadilydeducible

,the

+5oxidationstateinBiislessstablethanin

Sbforthereasonsdiscusdonp.226;notonly

isthesumofthe4thand5thionizationener-

giesforBigreaterthanforSb

(9.78vs.9.63

MJmol-')butthepromotionenergiesofoneof

theas2electronstoavacantndorbitalisalso

greaterforBi(andAs)cus-

sionsonredoxproperties(p.577)andtherole

ofdorbitals(p.222)y,

BishowsaninterestingremblancetoLainthe

crystalstructuresofthechlorideoxide,MOCl,

andintheisomorphismofthesulfatesanddou-

blenitrates;thisundoubtedlystemsfromthevery

similarionicradiiofthe2cations:Bi3+103,

La3+103.2pm.

Allcoordinationnumbersfrom1-10(and12)

areknownforthesub-group,though3,4,

5and6arebyfarthemostfrequently

1ixemplifiedbyRC=AS(~)(R=

2,4,6-BuZ3C6H2;cfRC-P,p.544)andby

theisolatedtetrahedralanionsS~AS~~-and

GeAs4*-(isoelectronicwithSi044-andGe044-)

whichoccurinthelustrousdarkmetal-

licZintlphasB@MAs4.@)CN2(bent)

isquitecommoninheterocyclicorganic

compounds(p.592)andinclusteranions

suchasAS^^-,Sby3-andAsl13-andtheir

derivates(p.588).Arareexampleoflin-

ear2-coordinateAswasrecentlyestablished

inthebis(mangane)complex[(q5-C5&Me>-

(CO)2Mn=As=Mn(C0)2(q5-C~&Me)]+,iso-

latedasitsdarkbrownsaltwithCF3S03-:

theangleatAswasfoundtobe176.3"

andtheAs-Mndistancewas215~m.(~)

Likewi,examplesofpyramidal3-coordinate

As,SbandBiareendemic,butplanar

CN3ixtremelyrare;examplesoccurin

'=,.

ANN,R,.

,I,.

25,264(1986).

.20,197-8(1981).

.27,1529-30(1988).

554Arnic,AntimonyandBismuthCh.13

compoundssuchas[PhAs(Cr(C0)5)2]and

[PhSb(Mn(r1’-CsH~)(C0)2)21(p.597)See

later,also,forexamplesofCN4(tetrahe-

dral,flattenedtetrahedralande-saw),CN5

(trigonalbipyramidalandsquarepyramidal)

andCN6(octahedral,3+3,andpentagonal

pyramidal).

Highercoordinationnumbersarelesscom-

7has

beenfoundinthetetradendatecrown-etherbis-

muthcomplex[BiC13(12-cr0wn-4)](~~)andin

thebismuthcomplex,[BiL],ofthenovelhep-

tadentateanionicligandof‘saltren’,(H3L),

i.e.(N(CH2CH2N-CHC6&0H)3).(l1)Thefirst

exampleofCN8wasfoundinthecolourless2:1

adduct[2BiC13.18-crown-6]whichwasshown

byX-rayanalysistoinvolveanunexpected

ionicstructurefeaturing8-coordinateBications,

viz.[BiC12(18-crown-6)1+~[BizCls12-.(lo)CN9

isreprentedbythediscretetris(tridentate)

complex[Si(-0-C(Bu‘)=C-N=C-C(Bu‘)

=0-+)3]inwhichBihasaface-capped,

slightly-twistedtrigonal-prismaticcoordination

environment.(12)Stillhighercoordinationnum-

bersareexemplifiedbyencapsulatedAs

andSbatomsinrhodiumcarbonylclus-

teranions:forexampleAsissurrounded

byabicappedsquareantiprismof

10Rh

atomsin[RhloA~(C0)22]~-,(~~)andSbis

surroundedbyanicosahedronof12Rhin

[Rh12Sb(C0)27]3-.(14)Ineachcatheanionis

thefirstexampleofacomplexinwhichAsorSb

actsasa5-electrondonor(5-electron

donorin[Rh~P(C0)21]~-):alltheclustersthen

haveprecilytheappropriatenumberofvalence

electronsfordosostructuresonthebasisof

Wade’srules(pp.161,174).

‘,,J.

.,.,1063-5(1989).

WAJ,,,N

,.47,1799-803(1994).

T,GO,J.

.107,3397-8(1985).

.20,243-9(1981).

,metallicChem.

213,351-63(1981).

13.3CompoundsofArnic,

AntimonyandBismuth(15)

metalliccompounds

andalloys(16,1n

Mostmetalsformarnides,antimonidesand

bismuthides,andmanyofthecommand

attentionbecauoftheirinterestingstructures

eborides

(p.145),carbides(p.297),silicides(p.3359,

nitrides(p.417)andphosphides(p.489),

classificationisdifficultbecauofthemultitude

ofstoichiometries,thecomplexitiesofthe

structuresandtheintermediatenatureofthe

pounds

areusuallyprepared

bydirectreactionoftheelementsinthe

requiredproportionsandtypicalcompositions

areMgAs,MsAs,M4As,M~As,MsAs2,MzAs,

MsAs~,M3As2,IM4As3,MgAs4,MAS,M3As4,

M2As3,nyand

theintermetallic

compoundxistoverarangeofcomposition,

andnonstoichiometryisrife.

The(electropositive)alkalimetalsofGroup1

formcompoundsM3E(E=As,Sb,Si)andthe

metalsofGroups2and12likewiformM3E2.

ThecanformallybewrittenasMf3E3-and

M2+3E3-2butthecompoundsareevenlessionic

thanLi3N(p.76)andhavemanymetallicprop-

er,otherstoichiometriesarefound

(,KBi2,CaBi3)whicharenotreadily

accountedforbytheionicmodeland,converly,

compoundsM3Eareformedbymanymetalsthat

arenotusuallythoughtofasunivalent,,Zr,

Hf;V,Nb,Ta;reclearlyalsostrong

additionalinteractionsbetweenunlikeatomsas

indicatedbythestructuresadoptedand

thehigh

mpofmanyofthecompounds,3Bimelts

”=Chemistryof

Arnic,AntimonyandBismuth,EllisHorwood,Chichester,

1990,350pp.

,Chap.21inComprehensiveInorganic

Chemistry,Vol.2,pp.547-683,PergamonPress,Oxford,

1973.

ER,.4,83-229(1968).A

comprehensivereviewwith532references.