Aromatic 5-silicon rings synthesized awiei koraa no

Nnuruyɛ Ho Dae a Adi Mfe Afeha no Baam

Bɛboro mfe ɔha no, wobuu aromaticity — quantum mechanical phenomenon a ɛma molecule ahorow bi a ɛte sɛ ring gyina pintinn soronko — sɛ carbon no fã titiriw. Benzene a wohuu no 1825 mu na August Kekulé dii ho dwuma wɔ nhyehyɛe mu wɔ 1865 mu no bɛyɛɛ abofra a wɔde nneɛma a ɛyɛ huam kyerɛw krataa, na nnuruyɛfo awo ntoatoaso ahorow kyekyee nnwuma mũ nyinaa wɔ ne nhyehyɛe a egyina carbon so no so. Nanso wɔ ade titiriw bi a wɔatumi ayɛ a ɛsan kyerɛw nnuru a ɛnyɛ abɔde mu nneɛma ho mmara mu no, nhwehwɛmufo ayɛ nkaa a edi kan a ɛyɛ huam koraa a ɛwɔ afã anum a silicon atɔm nyinaa na ɛwom. Saa pentasilacyclopentadienide anion yi nnyina hɔ mma nkonimdi a wɔayɛ ara kwa, na mmom nhwɛso mu nsakrae wɔ sɛnea yɛte nnuru a ɛka bom, molecule a ɛgyina pintinn, ne tumi a silicon wɔ a wɔmfaa nni dwuma a ɛboro dwuma a edi wɔ semiconductors mu ase.

Aromaticity: Stability Secret a Ɛkyekyeree Nnɛyi Chemistry

Sɛ wobɛkyerɛ nea enti a silicon nyinaa hua ring ho hia a, ɛsɛ sɛ wudi kan te nea hua de ma ankasa ase. Aromatic molecules nyɛ ring-shaped kɛkɛ — wɔwɔ electron nhyehyɛe soronko bi a pi electrons no delocalized wɔ ring nhyehyɛe no nyinaa mu, na ɛma "mununkum" a kyɛ electron density a ɛtew molecule no ahoɔden so kɛse. Saa delocalization yi di Hückel mmara akyi, a ɛka sɛ planar, cyclic molecule a (4n + 2) pi electrons — a n yɛ integer a ɛnyɛ negative — bɛda aromatic stabilization adi. Wɔ cyclopentadienide anion (carbon nkyerɛase no) fam no, ɛno kyerɛ sɛ pi ɛlɛtrɔnik 6 a wɔkyɛ wɔ carbon atom 5 mu.

Saa ahoɔden a ɛma ɛyɛ den yi nyɛ ade ketewaa bi. Benzene, carbon asia aromatic ring no, bɛyɛ 150 kJ/mol a ɛyɛ den sen sɛnea hypothetical cyclohexatriene a ɛwɔ localized double bonds bɛyɛ. Saa ahoɔden a ɛboro so no ne nea enti a nnuru a ɛyɛ huam di nnuruyɛ mu nnuru so (anyɛ yiye koraa no nnuru a wɔapene so no mu bɛboro 85% kura nkaa a ɛyɛ huam biako), ɛyɛ polymers a wɔayɛ no akyi dompe, na ɛyɛ ntamgyinafo atitiriw wɔ mfiridwuma mu nnuruyɛ mu a ne bo yɛ dɔla ɔpepepem ɔhaha pii afe biara.

Cyclopentadienide anion — carbon no nkaa a ɛyɛ huam a ɛwɔ afã anum — yɛ fapem pɛpɛɛpɛ. Ɛyɛ metallocene nnuruyɛ nnyinaso, na ɛma nneɛma a ɛma nneɛma yɛ kɛse te sɛ ferrocene a ɛsakraa organometallic nnuruyɛ bere a wohuu wɔn wɔ 1951. Asɛmmisa a ɛhaw nnuruyɛfo mfe du du pii no yɛ tẽẽ: sɛ carbon tumi yɛ eyi a, dɛn nti na silicon ntumi?

Silicon Akwanside: Nea Enti a Nneɛma a emu yɛ duru Ko tia Aromaticity

Silicon te carbon ase tẽẽ wɔ periodic table no so, ɛkyɛ valence electron anan, na ɛyɛ tetrahedral bonding geometries wɔ compounds dodow no ara mu. Wɔ krataa so no, ɛsɛ sɛ etumi yɛ nkaa a ɛyɛ huam. Wɔ nneyɛe mu no, silicon atom radius kɛse (1.17 Å versus carbon 0.77 Å) ne 3p orbitals a ɛtrɛw kɛse no de akwanside atitiriw ba afã pi-orbital overlap a etu mpɔn a aromaticity hwehwɛ no ho.

Wɔbuu silicon-silicon nkitahodi abien no ankasa sɛ entumi nyɛ yiye kosii sɛ Robert West kuw a ɛwɔ Wisconsin Sukuupɔn mu no yɛɛ disilene a edi kan a ɛyɛ den wɔ 1981. Saa bere no mpo, na saa nkitahodi abien yi yɛ mmerɛw koraa na ɛyɛ adwuma sen wɔn mfɛfo carbon no. Si=Si abien nkitahodi ahoɔden no bɛyɛ 310 kJ/mol sɛ wɔde toto 614 kJ/mol ma C=C ho a. Na delocalized pi bonding a wobenya wɔ silicon atɔm ring mũ no nyinaa mu no hwehwɛ sɛ wodi saa mmerɛwyɛ a efi awosu mu yi so bere a wɔkura planar geometry a ɛho hia ma orbital overlap no mu.

Mmɔden a wɔadi kan abɔ wɔ mfe 40+ mu no maa wɔyɛɛ nkaa a ɛyɛ huam a wɔde silicon asi ananmu fã bi, heterocycles a silicon wom, ne bɛyɛ ahorow. Nanso ring a ɛyɛ huam a ɛyɛ homoatomic koraa — atom biara a ɛwɔ ring no mu yɛ silicon — kɔɔ so yɛɛ whale fitaa a ɛwɔ kuw titiriw mu nnuruyɛ mu. Na asɛnnennen no yɛ abien: sɛ wɔbɛhyehyɛ silicon anum ring a ɛwɔ electron dodow a ɛfata na wɔama ayɛ nea ɛyɛ den sɛnea ɛbɛyɛ a ɛbɛkyerɛ ne su.

Nkɔsoɔ: Engineering Stability Denam Steric Ahobanbɔ so

Nneɛma a wɔde yɛ nneɛma a edii nkonim no de ne ho too ɔkwan bi a abɛyɛ sika kɔkɔɔ gyinapɛn a wɔde gyina kuw titiriw mu nnuru a ɛyɛ adwuma no so: akuw akɛse a wɔde si ananmu. Ɛdenam ligand akɛse a ɛma ɛlɛtrɔnik a wɔde bataa silicon atɔm biara a ɛwɔ ring no mu ho so no, nhwehwɛmu kuw no duu botae atitiriw abiɛsa ho bere koro mu. Akuw akɛse no de honam fam bɔɔ silicon-silicon nkitahodi a ɛyɛ adwuma no ho ban fii abɔnten reagents ho, wɔn electron-donating su ahorow no boa ma anion no ahoɔden a enye no gyinaa hɔ, na wɔn steric kɛse no hyɛɛ near-planar geometry a ɛho hia ma pi delocalization no mu den.

Pentasilacyclopentadienide a wɔayɛ no su no sii huam su no so dua denam akwan pii a ɛde ne ho so:

• X-ray crystallography daa Si-Si nkitahodi tenten a ɛkame ayɛ sɛ ɛyɛ pɛ adi wɔ ring no ho (~2.25 Å), a ɛne delocalized bonding hyia sen sɛ ɛbɛsesa nkitahodi biako ne abien
• Nuclear magnetic resonance (NMR) spectroscopy kyerɛɛ su a ɛma deshielding nhyehyɛe a ɛne aromatic ring current
hyia
• Nucleus-independent chemical shift (NICS) akontabuo maa nsusuiɛ a enye kɛseɛ baa ring mfimfini, akontabuo mu nsɛnkyerɛnneɛ a wɔgye tom kɛseɛ a ɛkyerɛ sɛ ɛyɛ huam
• UV-visible spectroscopy daa absorption features adi a ɛne delocalized pi-electron nsakraeɛ hyia wɔ silicon framework
no so
• Density functional theory (DFT) akontabuo sii so dua sɛ ahoɔden a ɛyɛ huam a ɛma ɛyɛ den, a wɔbu akontaa sɛ ɛyɛ 50-70 kJ/mol

Bere a ahoɔden a ɛma ɛyɛ huam no sua sen benzene 150 kJ/mol no, ɛyɛ kɛse araa ma ɛbɛma aduru no atumi atew ne ho na wɔatumi akyerɛ ne su wɔ dan mu hyew mu wɔ wim tebea a ɛnyɛ adwuma mu — ade a ɛyɛ nwonwa a wɔatumi ayɛ ama molecule a nnuruyɛfo dodow no ara gye dii sɛ entumi ntra hɔ wɔ ɔkwan a ɛyɛ den mu.

Beyond the Lab Bench: Wiase Ankasa Nkyerɛkyerɛmu

Silicon nkaa a ɛyɛ huam a wɔyɛ no bue nhwehwɛmu akwan a ɛtrɛw kɔ akyiri sen nhomasua mu anigye a wɔde hwehwɛ nneɛma mu. Nneɛma a ɛyɛ huam a egyina silicon so no betumi ada ɛlɛtrɔnik su ahorow adi a ɛsono koraa wɔ wɔn carbon analogs ho, a nea wobetumi de adi dwuma no fa nnwuma ahorow pii a ne bo yɛ den ho.

Silicon nyinaa hua a wɔahu no mfa aduru foforo bi nka katalog no ho kɛkɛ — ɛde molecule architecture kuw foforo koraa si hɔ. Mprempren dwumadie biara a wɔasi wɔ carbon huam so wɔ mfeɛ 160 a atwam no mu no wɔ ne yɔnko a egyina silicon so a ɛretwɛn sɛ wɔbɛhwehwɛ mu, a emu biara wɔ ɛlɛtrɔnik, aniwa, ne catalytic su a ɛbɛtumi ayɛ soronko.

Wɔ semiconductor mfiridwuma mu, baabi a silicon di tumi dedaw sɛ ade a wɔde yɛ fapem no, silicon a ɛyɛ huam betumi ayɛ ɛlɛtrɔnik nneɛma a ɛwɔ molecule mu. Pi ɛlɛtrɔnik a wɔayi afi baabi foforo a ɛwɔ saa nkaa yi mu no betumi de ahoɔden akɔ akwan horow a ɛsono wɔ silicon a ɛdɔɔso ho, na ɛde akwan a ɛkɔ molecule ɛlɛtrɔnik ne quantum kɔmputa so nneɛma so ma. Esiane sɛ wɔkyerɛ sɛ wiase nyinaa semiconductor gua no bɛboro dɔla ɔpepepem biako wɔ afe 2030 mu nti, nkɔso a ɛrenya nkɔanim mpo wɔ molecule electronics a egyina silicon so mu no de aguadi mu nsunsuanso kɛse ba.

Wɔ photovoltaics mu no, silicon aromatic rings betumi ayɛ adwuma sɛ chromophores foforo a ɛtwa hann. Wɔn absorption ne emission su — tunable through substituent modification — betumi ama silicon-based organic light-emitting diodes (OLEDs) akuw foforo anaa owia nkwammoaa sensitizers a ɛma nsonsonoe a ɛda atetesɛm silicon photovoltaics ne organic owia mfiridwuma a ɛreba ntam no atumi ayɛ adwuma.

Asɛmmisa a ɛfa Catalyst ho: Silicon Metallocenes a ɛwɔ Wim

Ebia anidasoɔ a ɛyɛ anigyeɛ ntɛm ara ne tumi a ɛwɔ metallocenes a egyina silicon so. Ɛkame ayɛ sɛ carbon cyclopentadienide anion no yɛ sandwich afrafrade a ɛne nsakrae dade biara, na saa metallocenes yi yɛ nneɛma a ɛho nhia a ɛma nneɛma yɛ kɛse wɔ polymer nnuruyɛ mu. Ziegler-Natta ne metallocene catalysts bom gyina polyethylene ne polypropylene bɛboro tɔn ɔpepem 100 a wɔyɛ afe biara so — gua a ne bo bɛyɛ dɔla ɔpepepem 200.

Sɛ pentasilacyclopentadienide tumi yɛ biako ne nsakrae dade sɛnea ne carbon analog yɛ no a, anka silicon metallocenes a efi mu ba no benya steric ne ɛlɛtrɔnik su soronko koraa. Silicon ring kɛse no bɛma "bite angle" a ɛtrɛw atwa dade mfinimfini ho ahyia, a ebetumi ama wɔatumi apaw nneɛma foforo wɔ olefin polymerization, C-H activation, ne catalytic nsakrae afoforo mu. Nkɔsoɔ ketewaa bi mpo a ɛba wɔ catalyst adwumayɛ mu wɔ saa mfiridwuma mu nsenia yi mu no kyerɛ aseɛ kɔ dɔla ɔpepepem pii boɔ ne ahoɔden a wɔde di dwuma ne nneɛma a wɔsɛe no so tew kɛseɛ.

Mfitiaseɛ nhwehwɛmu nhwehwɛmu kyerɛ sɛ silicon metallocenes nso betumi ada magnetic su a ɛkɔ anim adi sɛ wɔde toto wɔn carbon mfɛfoɔ ho a, ɛbue dwumadie wɔ spintronics ne magnetic data storage nneɛma mu. Afuo no yɛ mmeranteɛ, nanso wɔreto nsusuiɛ fapem no dedaw wɔ nhwehwɛmu akuo ahodoɔ pii mu wɔ wiase nyinaa.

Nnɛyi Nhwehwɛmu Dwumadie a Ɛyɛ Den a Wɔhwɛ so

Nkɔsoɔ te sɛ silicon nkaa a ɛyɛ huam yɛ nnɛyi nyansahu mu nhwehwɛmu a ɛyɛ den no ho nhwɛsoɔ — mfeɛ pii nnwuma a ɛfa akuo a ɛfa nnwuma ahodoɔ ho, nnwinnadeɛ a ne boɔ yɛ den, mmara a wɔdi so, mmoa a wɔde ma, ne wiase nyinaa adwumayɛkuo a ɛrekɔ soro. Nhwehwɛmu akuw ne nnwuma a wɔafi ase a wɔde wɔn nneɛma a wɔahu no di gua no hyia adwumayɛ mu nsɛnnennen a ɛne adwumakuw biara a ɛwɔ mfinimfini de di asi: nnwuma du du pii a wɔyɛ no akyi a wobedi, nneɛma a wɔkra ne adetɔnfo ntam abusuabɔ a wɔbɛhwɛ so ama nnuru ne nnwinnade titiriw, HR a wodi ho dwuma ma akuw a wɔdannan wɔn ho a wɔyɛ postdocs ne asuafo a wɔawie sukuu, ne kyerɛwtohɔ ahorow a wɔyɛ no yiye a wɔbɛhwɛ so de abɔ adwene mu agyapade ho ban.

Platforms te sɛ Mewayz di saa adwumayɛ mu nsɛnnennen yi ho dwuma pɛpɛɛpɛ. Ɛnam sɛ ɛwɔ module 207 a wɔaka abom a ɛfa CRM, invoicing, project management, HR, ne analytics ho nti, Mewayz ma ahyehyɛdeɛ a nhwehwɛmu-di so no nhyehyɛeɛ baako a wɔde bɛhwɛ adwumayɛ fã a ɛfa nnoɔma foforɔ ho. Sɛ anka wɔbɛka spreadsheets, email nkɔnsɔnkɔnsɔn, ne software nnwinnade a wɔatwa mu no abom no, akuw betumi adi adwuma no mu nsɛntitiriw akyi, ahwɛ wɔn a wɔde nneɛma ma no sika a wɔde tua ho ka ma laboratory reagents, ayɛ kuw nhyehyɛe ho nhyehyɛe, na wɔayɛ sikasɛm ho amanneɛbɔ a sikakorabea ahorow hwehwɛ — ne nyinaa fi platform biako so. Wɔ akuw 138,000+ a wɔde Mewayz di dwuma dedaw wɔ wiase nyinaa no fam no, saa adwumayɛ sohwɛ a ɛwɔ mfinimfini yi kyerɛ bere kakraa bi wɔ adwumayɛ so na bere pii a wɔde bɛpia nea nyansahu betumi ayɛ no ahye.

Nea Ɛba Akyi: Periodic Table no Wɔ Ahintasɛm Pii

Silicon nyinaa hua ring a wɔyɛ no yiye no ma asɛmmisa yi sɔre ntɛm ara: Kuw 14 mu nneɛma afoforo no nso ɛ? Germanium, tin, ne kɔbere nyinaa kyɛ silicon anan-valence-electron nhyehyɛe, na emu biara de n’ankasa nsɛnnennen ahorow a ɛbɛma wɔanya ring nhyehyɛe ahorow a ɛyɛ huam a ɛyɛ den no ba. Germanium hua nkaa, titiriw, mprempren wobu no sɛ ɛyɛ botae ankasa a ɛbɛn bere tenten, esiane gyinabea a germanium wɔ wɔ silicon ne nneɛma a emu yɛ duru ntam nti.

Wɔ Kuw 14 akyi no, wɔatrɛw adwene a ɛfa huam ho no mu dedaw akɔ boron akuwakuw (boranes ne carboranes no da huam a ɛwɔ afã abiɛsa adi), phosphorus nkaa, ne mpo dade nyinaa hua nhyehyɛe te sɛ Al42− tetraanion a wodii kan huu no wɔ afe 2001. Ade foforo biara a ɛma ɛyɛ huam no trɛw nnwinnade a ɛwɔ hɔ ma nneɛma no mu nyansahufo ne nnuruyɛfo a wɔyɛ nneɛma a wɔde yɛ nneɛma, a wɔyɛ molecule adansi nneɛma a ɛwɔ su ahorow a nhyehyɛe ahorow a egyina carbon so nkutoo ntumi nyɛ ho mfonini.

Pentasilacyclopentadienide a wɔyɛ no nso si su a ɛtrɛw wɔ nnɛyi nnuruyɛ mu so dua: nhyehyɛe a wɔhwehwɛ wɔ kuw titiriw mu nneɛma mu ma bonding motifs a kan no na wɔde asie ama carbon. Wɔ mfe aduonu a atwam no mu no, wɔahu nnuru a ɛyɛ den a silicon-silicon nkitahodi abiɛsa, phosphorus-phosphorus nkitahodi abiɛsa, ne boron-boron nkitahodi abiɛsa mpo wom nyinaa. Wɔde mfe du du pii a wɔde bɔɔ mmɔden a entumi nyɛ yiye ne nsusuwii mu adwenem naayɛ dii saa nneɛma a wohui yi mu biara anim, na emu biara abue akwan foforo ama nneɛma a wɔde yɛ nneɛma.

Nea ɛma silicon ring a ɛyɛ huam no yɛ nea ɛho hia titiriw ne abusuabɔ a ɛda ɛne nnuruyɛ mu nsusuwii ahorow a ɛho hia sen biara wɔ aguadi mu no biako ntam tẽẽ. Aromaticity nyɛ adesua mu abstraction — ɛyɛ molecule su a ɛhyɛ nnuru, plastic, dyes, explosives, agrochemicals, ne electronic nneɛma ase. Saa su yi a wɔtrɛw mu kɔ silicon so no nwie row bi wɔ adesua nhoma pon so kɛkɛ. Ɛbue silicon nnuruyɛ bere foforo a element no tumi trɛw kɔ akyiri sen crystalline wafers a ɛwɔ yɛn kɔmputa chips mu no na ɛkɔ molecule nhyehyɛe a, ɛde besi nnɛ no, na ɛyɛ carbon nkutoo de no mu.

Nsɛmmisa a Wɔtaa Bisa

Dɛn ne silicon ring a ɛyɛ huam?

Silicon ring a ɛyɛ huam yɛ molecule a silicon atom ahorow yɛ nhyehyɛe a ɛyɛ den, ɛte sɛ ring a ɛwɔ "aromatic" stability soronko, su a wosusuw bere tenten sɛ ɛyɛ carbon nkutoo de. Eyi hwehwɛ sɛ wɔkyɛ ɛlɛtrɔnik ahorow pɛpɛɛpɛ wɔ ring no ho, na ɛma ɛyɛ den soronko. Saa ade a wɔahu yi trɛw adwene a ɛfa huam ho no mu titiriw kɔ akyiri sen abɔde mu nneɛma a nkwa wom te sɛ silicon.

Dɛn nti na wobu saa nsɛm a wɔaka abom yi sɛ ɛyɛ ade titiriw a wɔatumi ayɛ?

Bɛboro mfe ɔha no, na huam yɛ su a ɛkyerɛkyerɛ molecule a egyina carbon so te sɛ benzene mu. Sɛ wɔyɛ nkatabo a ɛyɛ den na ɛyɛ huam a efi silicon mu koraa a wotumi yɛ no di adanse sɛ nnuru ho adwene titiriw yi nyɛ carbon pɔtee bi. Ɛsan kyerɛw adesua nhoma mu nimdeɛ na ebue akwan foforo kɛse a wobetumi afa so ayɛ nneɛma foforo a ɛwɔ ɛlɛtrɔnik su soronko a kan no na wontumi nsusuw ho mma silicon nnuru.

Dɛn ne silicon rings yi a wobetumi de adi dwuma?

Bere a wɔda so ara wɔ nhwehwɛmu mfiase no, saa silicon nkaa a ɛyɛ huam yi betumi ama wɔde adi dwuma ɔsesɛw. Wobetumi de wɔn ɛlɛtrɔnik nhyehyɛe soronko no adi dwuma de ayɛ semiconductor ahorow foforo, nneɛma a ɛkɔ anim a wɔde yɛ ɛlɛtrɔnik mfiri, anaasɛ nneɛma a ɛma nneɛma yɛ adwuma yiye. Sɛ wɔte sɛnea wɔhyɛ hua so wɔ silicon mu ase a, ebetumi abue nneɛma ho nyansahu nkorabata foforo koraa, adesua titiriw ma nnuruyɛfo a wɔde nneɛma te sɛ Mewayz di dwuma (a ɛwɔ module 207 a ne bo yɛ $19/mo).

Ɔkwan bɛn so na saa ade a wɔahu yi ne silicon nnuruyɛ a ɛwɔ hɔ dedaw no wɔ abusuabɔ?

Saa ade a wɔahu yi twa atetesɛm mu adwene a ɛfa silicon nnuruyɛ ho no mpoa. Mpɛn pii no, silicon yɛ nkitahodi biako, na ɛma nkɔnsɔnkɔnsɔn ne nhyehyɛe ahorow a ɛte sɛ alkanes (hydrocarbons a ɛyɛ ma) kɛse. Wɔabɔ ring a ɛyɛ huam a ɛyɛ den no kyerɛ sɛ silicon betumi de ne ho ahyɛ nkitahodi nhyehyɛe ahorow a ɛyɛ den kɛse mu, a ɛte sɛ carbon, a ebetumi ama wɔanya nnuru a egyina silicon so kuw foforo koraa a ɛwɔ su ahorow a ɛsono ne silicones ne silanes a wɔtaa de di dwuma.