Zobba na siliki 5 na ƙamshi waɗanda aka haɗa a ƙarshe

An Gane Mafarkin Chemistry Tsawon Ƙarni

Sama da shekaru ɗari, ƙamshi - al'amarin inji mai ƙididdigewa wanda ke ba da kwanciyar hankali na musamman ga wasu ƙwayoyin cuta masu siffar zobe - an ɗauke shi keɓantaccen yanki na carbon. Benzene, wanda aka gano a cikin 1825 kuma an warware shi ta August Kekulé a cikin 1865, ya zama ɗan bota don abubuwan ƙanshi, kuma tsararrun masanan chemists sun gina masana'antu gabaɗaya akan tsarin tushen carbon. Amma a cikin wata babbar nasara da ta sake rubuta ka'idojin sinadarai na inorganic, masu bincike sun hada zobe mai cike da kamshi na farko wanda ya hada da kwayoyin halitta na silicon. Wannan pentasilacyclopentadienide anion yana wakiltar ba kawai nasara ta roba ba, amma canjin yanayi a yadda muke fahimtar haɗin sinadarai, kwanciyar hankali na kwayoyin halitta, da yuwuwar da ba a iya amfani da shi na silicon fiye da rawar da yake takawa a semiconductor.

Ƙashin Ƙashin Ƙashin Ƙashin Ƙashin Ƙashin Ƙashin Ƙashin Ƙashin Ƙarƙashin Ƙarƙashin Ƙarƙashin Ƙarƙashin Ƙarƙashin Ƙarƙashin Ƙarƙashin Ƙarƙashin Ƙarƙashin Ƙarƙashin Ƙarƙashin Ƙarƙashin Ƙarƙashin Ƙarƙashin Ƙarƙashin Ƙaƙwalwar Zamani

Don fahimtar dalilin da yasa zoben kamshi na siliki ke da mahimmanci, kuna buƙatar fara fahimtar abin da ƙamshi ke bayarwa. Kwayoyin kamshi ba kawai nau'in zobe ba ne - suna da tsarin na'urar lantarki na musamman inda pi electrons ke karkatar da su a cikin dukkan tsarin zoben, suna ƙirƙirar "girgije" na yawan adadin lantarki wanda ke rage ƙarfin kwayoyin. Wannan ƙaddamarwa ya bi ka'idar Hückel, wanda ya bayyana cewa tsarin tsarin, kwayoyin halitta na cyclic tare da (4n + 2) pi electrons - inda n ba shi da ma'ana - zai nuna kwanciyar hankali. Ga cyclopentadienide anion (siffar carbon), wannan yana nufin 6 pi electrons da aka raba a tsakanin 5 carbon atoms.

Wannan ƙarfin ƙarfafawa ba ƙaramin abu bane. Benzene, zoben kamshi na carbon shida, yana da kusan 150 kJ/mol ya fi kwanciyar hankali fiye da hasashen cyclohexatriene tare da haɗin gwiwa biyu na gida. Wannan karin kwanciyar hankali shine dalilin da ya sa mahadi masu kamshi ke mamaye sinadarai na harhada magunguna (sama da kashi 85% na magungunan da aka yarda da su sun ƙunshi aƙalla zobe ɗaya na kamshi), suna zama ƙashin bayan polymers ɗin roba, kuma suna aiki a matsayin maɓalli mai mahimmanci a cikin tsarin sinadarai na masana'antu da darajar ɗaruruwan biliyoyin daloli a shekara.

Anion cyclopentadienide - zoben kamshi na carbon mai membobi biyar - daidai yake da tushe. Yana samar da tushen sinadarai na metallocene, yana ba da damar masu haɓakawa kamar ferrocene wanda ya canza ilimin sunadarai na organometallic bayan gano su a cikin 1951. Tambayar da ta mamaye masanan chemist shekaru da yawa ta kasance madaidaiciya: idan carbon zai iya yin wannan, me yasa silicon ba zai iya ba?

Katangar Silicon: Me yasa Abubuwa Masu Nauyi Ke Hana Ƙashin Ƙashin Ƙashin

Silicon yana zaune kai tsaye ƙasa da carbon akan tebur na lokaci-lokaci, yana raba valence electrons guda huɗu, kuma yana samar da haɗin gwiwar tetrahedral a yawancin mahadi. A kan takarda, ya kamata ya kasance yana iya samar da zoben aromatic. A aikace, radius atomic mafi girma na silicon (1.17 Å tare da carbon's 0.77 Å) da ƙarin ɓangarorin 3p orbitals suna haifar da cikas ga nau'in tasiri mai tasiri na gefen pi-orbital wanda ƙanshi ke buƙata.

Silicon-silicon biyu bonds an yi la'akari da kansu ba zai yiwu ba har sai da ƙungiyar Robert West a Jami'ar Wisconsin suka haɗa disilene na farko a cikin 1981. Ko da haka, waɗannan haɗin biyu sun kasance masu rauni kuma sun fi ƙarfin aiki fiye da takwarorinsu na carbon. Ƙarfin haɗin Si = Si biyu yana kusan 310 kJ/mol idan aka kwatanta da 614 kJ/mol na C=C. Samun rarrabuwa pi bonding a cikin duka zoben silicon atom ɗin yana buƙatar shawo kan wannan raunin da ke tattare da shi yayin da yake kiyaye tsarin lissafi mai mahimmanci don zoben orbital.

Ƙoƙarin da aka yi a baya sama da shekaru 40+ sun samar da zoben kamshi da aka maye gurbin siliki, kekuna masu ɗauke da siliki, da ƙima iri-iri. Amma zoben ƙamshi na homoatomic cikakke - kowane zarra a cikin zoben shine silicon - ya kasance farin whale na babban rukunin sunadarai. Kalubalen ya kasance sau biyu: haɗa zoben siliki guda biyar tare da madaidaicin ƙidayar lantarki da kiyaye shi da ƙarfi don siffata.

Ci gaba: Ƙarfafa Injiniya Ta Hanyar Kariya

Haɗin nasarar ya dogara ne akan dabarar da ta zama ma'aunin gwal don daidaita ma'auni na babban rukuni: manyan ƙungiyoyi masu maye gurbin. Ta hanyar haɗa manyan igiyoyi masu ba da gudummawar lantarki zuwa kowane zarra na silicon a cikin zobe, ƙungiyar binciken ta cimma maƙasudai masu mahimmanci guda uku a lokaci guda. Ƙungiyoyin masu girma a jiki sun ba da kariya ga haɗin gwiwar silicon-silicon masu amsawa daga reagents na waje, kaddarorinsu na ba da gudummawar lantarki sun taimaka wajen daidaita mummunan cajin anion, kuma yawancin su ya tilasta tsarin lissafi na kusa-planar da ake buƙatar pi delocalization.

Halayen haɗin gwiwar pentasilacyclopentadienide ya tabbatar da yanayin ƙamshi ta hanyoyi masu zaman kansu da yawa:

• X-ray crystallographyya bayyana kusa-daidai Si-Si bond tsawon kusa da zobe (~ 2.25 Å), daidai da delocalized bonding maimakon musanya guda da biyu shaidu
• Nuclear Magnetic Resonance (NMR) spectroscopyya nuna sifofi na deshielding daidai da zobe na yanzu
Ƙididdigar kemikal mai zaman kanta ta Nucleus (NICS)ya haifar da ƙima mara kyau a cibiyar zobe, alamar ƙididdigewa da aka yarda da ita ta ƙanshin ƙanshi
• UV-bayyanawa spectroscopy yana nuna fasalulluka na sha wanda ya yi daidai da rarrabuwar canjin pi-electron a cikin tsarin silicon
Ƙididdigar ka'idar aikin ƙididdigewa (DFT)tabbatar da ƙarfin ƙarfafa ƙarfin ƙamshi, wanda aka kiyasta a 50-70 kJ/mol

Yayin da makamashin daidaitawar kamshi ya yi ƙasa da 150 kJ/mol na benzene, yana da matuƙar isa don sanya wurin keɓantacce kuma ana iya siffanta shi a yanayin zafin ɗaki a ƙarƙashin yanayin yanayi mara kyau - babban nasara ga kwayar halittar da yawancin masanan kimiyya suka yi imani ba zai iya wanzuwa cikin tsayayyen tsari ba.

Bayan Wurin Lab: Abubuwan Tafiya na Gaskiya

Haɗin zoben siliki mai kamshi yana buɗe hanyoyin bincike waɗanda suka wuce yunƙurin ilimi. Abubuwan kamshi na tushen Silicon na iya nuna kaddarorin lantarki daban-daban da abubuwan analog ɗin su na carbon, tare da yuwuwar aikace-aikacen da suka mamaye masana'antu masu daraja da yawa.

Gano duk-silicon aromaticity ba kawai ƙara sabon fili a cikin kasida - ya kafa gaba ɗaya sabon aji na kwayoyin gine. Kowane aikace-aikacen da aka gina akan ƙamshin carbon cikin shekaru 160 da suka gabata yanzu yana da takwaransa na tushen silicon da ke jiran a bincika, kowannensu yana da yuwuwar sifofin lantarki, na gani, da katalin kuzari.

A cikin fasaha na semiconductor, inda silicon ya riga ya mamaye matsayin kayan tushe, mahadi na siliki na ƙamshi na iya zama kayan aikin lantarki na sikelin sikelin. Pi electrons da aka ware a cikin waɗannan zoben na iya yin yuwuwar gudanar da caji ta hanyoyin da suka bambanta da siliki mai girma, suna ba da hanyoyi zuwa ga na'urorin lantarki da ƙididdigar ƙididdigewa. Tare da kasuwar semiconductor na duniya da aka yi hasashen za ta haura dala tiriliyan 1 nan da shekarar 2030, har ma da ci gaban da aka samu a cikin na'urorin lantarki na tushen silicon na da tasirin kasuwanci mai yawa.

A cikin photovoltaics, zoben aromatic silicon na iya aiki azaman chromophores na girbi haske. Shayewarsu da kaddarorin fitar da su - wanda za'a iya daidaita su ta hanyar gyare-gyaren canji - na iya ba da damar sabbin nau'ikan diodes masu fitar da haske na tushen silicon (OLEDs) ko na'urorin wayar da kan hasken rana waɗanda ke cike gibin da ke tsakanin hotunan siliki na gargajiya da fasahar hasken rana masu tasowa.

Tambayar Mai Haɓakawa: Silicon Metallocenes akan Horizon

Wataƙila mafi kyawun abin farin ciki nan da nan shine yuwuwar ƙirar ƙarfe na tushen silicon. Carbon's cyclopentadienide anion yana samar da mahadi na sanwici tare da kusan kowane ƙarfe na canzawa, kuma waɗannan metallocenes sune abubuwan da ke haifar da haɓakawa a cikin sinadarai na polymer. Ziegler-Natta da metallocene masu kara kuzari tare suna ba da gudummawar samar da sama da tan miliyan 100 na polyethylene da polypropylene a duk shekara - kasuwa mai darajar kusan dala biliyan 200.

Idan pentasilacyclopentadienide zai iya daidaitawa don jujjuya karafa kamar yadda analog ɗinsa na carbon ke yi, sakamakon silicon metallocenes zai mallaki kaddarorin sitiriyo da lantarki daban-daban. Babban zoben siliki zai haifar da “kusurwar cizo” mai fadi a kusa da tsakiyar karfe, mai yuwuwar ba da damar sabbin zabuka a cikin olefin polymerization, kunna CH, da sauran sauye-sauye na catalytic. Ko da ingantacciyar haɓakar haɓakar haɓakar haɓakawa a wannan sikelin masana'antu yana fassara zuwa biliyoyin daloli a cikin ƙimar da gagarumin raguwar amfani da makamashi da sharar gida.

Nazarin lissafi na farko sun nuna cewa silicon metallocenes na iya nuna ingantattun kaddarorin maganadisu idan aka kwatanta da takwarorinsu na carbon, buɗe aikace-aikace a cikin spintronics da kayan adana bayanai na maganadisu. Filin matashi ne, amma an riga an kafa tushen ka'idar a cikin ƙungiyoyin bincike da yawa a duniya.

Sarrafar da Matsalolin Ayyukan Bincike na Zamani

Nasarorin da aka samu kamar zoben siliki na ƙamshi suna misalta sarƙar binciken kimiyya na zamani - ayyukan shekaru da yawa da suka haɗa da ƙungiyoyin ladabtarwa, kayan aiki masu tsada, bin ƙa'ida, sarrafa tallafi, da haɓaka haɗin gwiwar duniya. Ƙungiyoyin bincike da farawar da ke tallata bincikensu suna fuskantar ƙalubale na aiki waɗanda ke adawa da na kowane kamfani mai matsakaicin girman: bin diddigin ayyuka da yawa, gudanar da alaƙar saye da tallace-tallace don ƙwararrun sinadarai da kayan aiki, kula da HR don ƙungiyoyin postdocs da ɗaliban da suka kammala karatun digiri, da kuma kiyaye bayanan ƙima don kare dukiyar ilimi.

Dandali kamar suMewayz suna magance daidai wannan hadaddun aiki. Tare da 207 hadedde modules span CRM, daftarin aiki, gudanar da ayyuka, HR, da kuma nazari, Mewayz ya ba da bincike-kore kungiyoyin tsarin guda don gudanar da harkokin kasuwanci bangaren na bidi'a. Maimakon haɗa maƙunsar bayanai, sarƙoƙi na imel, da kayan aikin software da aka cire, ƙungiyoyi za su iya bin diddigin matakan aikin, sarrafa daftarin daftarin kayayyaki don masu gyara dakin gwaje-gwaje, daidaita jadawalin ƙungiyar, da samar da rahoton kuɗi waɗanda hukumomin bayar da tallafi ke buƙata - duk daga dandamali ɗaya. Ga ƙungiyoyin 138,000+ da suka riga suna amfani da Mewayz a duniya, irin wannan nau'in sarrafa kayan aiki na tsakiya yana nufin ƙarancin lokaci akan aikin gudanarwa da ƙarin lokacin tura iyakokin abin da kimiyya za ta iya cimma.

Abin da ke zuwa na gaba: Tebur na lokaci-lokaci yana da Sirrin

Nasarar da aka samu na zoben kamshi na siliki nan da nan ya haifar da tambaya: menene game da sauran abubuwan Rukunin 14? Germanium, tin, da jagora duk suna raba tsarin siliki huɗu-valence-electron, kuma kowannensu yana gabatar da nasa ƙalubale don cimma tsayayyen tsarin zobe na kamshi. Zoben kamshi na Germanium, musamman, yanzu ana ɗaukarsu a matsayin manufa ta kusa, idan aka yi la'akari da matsakaicin matsayi na germanium tsakanin silicon da abubuwa masu nauyi.

Bayan Rukunin 14, an riga an ƙaddamar da manufar aromaticity zuwa gungu na boron (Boranes da carboranes suna nuna ƙamshi mai girma uku), zoben phosphorus, har ma da tsarin ƙamshi na ƙarfe na ƙarfe kamar Al4²⁻ tetraanion na farko da aka kwatanta a cikin 2001. Kowane sabon sabbin abubuwan da ke samun aromaticity masu haɓakawa da haɓaka kayan aikin haɓakawa da haɓaka kayan aikin haɓaka kayan aikin haɓakawa da haɓaka kayan aikin haɓaka kayan aikin ƙarfe tubalan ginin kwayoyin halitta tare da kaddarorin da ba za a iya yin su ta hanyar tsarin tushen carbon kadai ba.

Haɗin pentasilacyclopentadienide kuma yana tabbatar da ingantaccen yanayi a cikin ilmin sinadarai na zamani: bincike na yau da kullun na manyan rukunoni don haɗin kai motifs da aka tanada don carbon. A cikin shekaru ashirin da suka wuce, an samu tabbatattun abubuwan da ke ɗauke da silikon-Silicon sau uku, da phosphorus-phosphorus sau uku, har ma da boron-boron sau uku. Kowane ɗayan waɗannan binciken ya kasance a gaban shekaru da yawa na yunƙurin gazawar da kuma shakku na ka'ida, kuma kowannensu ya buɗe sabbin hanyoyin ƙirar kayan aiki.

Abin da ke sa zoben siliki mai kamshi ke da mahimmanci musamman shine haɗin kai kai tsaye zuwa ɗaya daga cikin mahimman dabarun sinadarai na kasuwanci. Ƙanshi ba ƙaƙƙarfan ilimi ba ne - ƙayyadaddun kwayoyin halitta ne da ke ƙarƙashin magunguna, robobi, rini, fashewar abubuwa, agrochemicals, da kayan lantarki. Ƙaddamar da wannan kadara zuwa siliki ba kawai kammala layi a cikin tebur na littafi ba. Yana buɗe sabon zamani na silica chemistry inda yuwuwar sinadarin ya wuce fiye da wafers crystalline a cikin kwakwalwan kwamfutanmu kuma zuwa cikin tsarin ƙirar kwayoyin halitta wanda, har yanzu, mallakar carbon ne na musamman.