EXAMINATION FOR THE DEGREE OF BACHELOR OF SCIENCES WITH EDUCATION PEPERIKSAAN IJAZAH SARJANA MUDA SAINS DENGAN PENDIDIKAN

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1 UIVERSITY OF MALAYA UIVERSITI MALAYA EXAMIATIO FOR THE DEGREE OF BACHELOR OF SCIECES PEPERIKSAA IJAZAH SARJAA MUDA SAIS EXAMIATIO FOR THE DEGREE OF BACHELOR OF SCIECES WITH EDUCATIO PEPERIKSAA IJAZAH SARJAA MUDA SAIS DEGA PEDIDIKA ACADEMIC SESSIO 2011/2012 : SEMESTER 2 SESI AKADEMIK 2011/2012 : SEMESTER 2 SCEP3110/SCESS3110 : Inorganic Chemistry III Kimia Takorganik III June 2012 Jun 2012 Time : 2 hours Masa : 2 jam ISTRUCTIOS TO CADIDATES: ARAHA KEPADA CALO: This examination paper consists of sections A and B. Kertas ini mengandungi Bahagian A dan Bahagian B.. Questions should be answered according to the instruction given in each section Jawab soalan mengikut arahan yang diberikan dalam setiap bahagian. (This question paper consists of 6 questions on 7 printed pages) (Kertas ini mengandungi 6 soalan dalam 7 halaman yang dicetak)

2 SCES3110/SCEP3110/02 PART/BAHAGIA A (65 marks/markah) Answer ALL questions. Jawab SEMUA soalan. 1. (a) The Fisher carbene complex, (CO) 3 Cr=C(OCH 3 )(Ph) may be synthesized from Cr(CO) 6 with suitable reagents. Describe the formation of this complex. Compare the reactivity of this Fisher carbene complex with the Schrock type carbene complex, (C 5 H 5 ) 2 Ta=CH 2 (CH 3 ). Kompleks karbena Fischer, (CO) 3 Cr=C(OCH 3 )(Ph) boleh disediakan daripada Cr(CO) 6 dengan menggunakan reagen yang sesuai. yatakan pembentukan kompleks ini. Bandingkan kereaktifan kompleks karbena Fisher ini dengan kompleks karbena jenis Schrock, (C 5 H 5 ) 2 Ta=CH 2 (CH 3 ). Draw the structures and describe the bonding involved in the formation of the following compounds: Lukiskan struktur dan nyatakan pengikatan yang terlibat bagi pembentukan sebatian yang berikut: Titanocene is a dimer with η 5 :η 5 cyclopentadienediyl,fulvalenediyl and two hydride bridges. Titanosen, sejenis dimer dengan η 5 :η 5 siklopentadienediil fulvalenediil dan dua titian hidrida. Magnesocene. Magnesosen. (c) Specify the electron count at each metal centre (Ru, Ir and Pt) of the following complexes: Tentukan bilangan electron pada setiap logam dalam kompleks yang berikut: Cl Cl Ru O O 2 Ir Cl (CH 2 ) 4 SO 3 a

3 SCES3110/SCEP3110/03 (iii) (19 marks/markah) 2. Identify A to E for the following reactions: Tentukan A sehingga E bagi tindak balas yang berikut: (a) Metallation of ferrocene with n-buli gives compound A which will react further with Ph 2 PCl to yield compound B. Pelogaman ferosena dengan n-buli menghasil sebatian A yang bertindakbalas dengan Ph 2 PCl menghasil sebatian B. Protonation of 18 valence electron (VE), diolefin complex with electron deficient metal will give complex C which exists in a dynamic equilibrium to complex D and E. Complex C is 16 VE type, with an enyl ligand. At low temperature, complex D forms C-H M bridge to compensate the electron deficiency at the metal centre. If M=Ir, E will be formed where metal hydride formation dominates. Pemprotonan kompleks dwiolefin yang berelektron valens 18, logamnya kekurangan elektron menghasil kompleks C di mana berekuilibrium dinamik dengan kompleks D dan E. Kompleks C ialah jenis16 VE mempunyai ligan enil. Pada suhu rendah, kompleks D membentuk titian C-H M bagi mengatasi kekurangan elektron pada logam. Jika M=Ir, E akan terbentuk dimana hidrida logam dominat. H + C D E M 18 VE M = Co, Rh, Ir 16 VE M = Co, Rh C - H M bridge 18 VE M = Ir metal hydride (9 mark/markah)

4 SCES3110/SCEP3110/04 3. (a) n-buli reacts with strong organic CH-acids such as (C) 3 C-H, CH 3 COOH and C 6 H 5 CH 3 to give high yield metallation products. In each case give their respective products. n-buli bertindak balas dengan sebatian organik asid kuat CH-asid seperti (C) 3 C-H, CH 3 COOH dan C 6 H 5 CH 3 menghasil produk metalasi. Bagi setiap kes berikan hasilnya. Addition of MeLi to nitrile compound (with C- multiple bond) will conveniently yield ketones. Complete the following reaction: Tindakbalas tambahan MeLi dengan sebatian nitrile (dengan ikatan multipel C- ) mudah menghasil ketone. Tuliskan tindakbalas yang berikut: hydrolysis hydrolysis n-buli + Me-CΞ X Y Z Ketone Identify compounds X, Y and Z. Tentukan sebatian X, Y dan Z. (9 marks/markah) 4. (a) Grignard reagents have been widely used for organic synthesis. Give the intermediates and the products of the following reactions: Reagen Grignard digunakan dengan meluas bagi penyediaan sebatian organik. Berikan perantaraan dan hasil bagi tindak balas yang berikut: (iii) MeMgCl + R 2 C=O I PhMgBr + R C J BuMgI + R 2 C=R K Hydroboration is one of the most versatile methods in organic synthesis. However the products of their subsequent reactions are important. Write the mechanisms and final products of the reactions below: Penghidroboranan merupakan kaedah yang versatile Hydroboration dalam sentesis organik. Walau bagaimanapun hasil tindak balas berikutnya yang penting. Tuliskan mekanisme dan hasil bagi tindak balas yang berikut: H 2 O/OH - HCrO 4 - L RCH 2 CH 2 BR 2 Et 2 Cl M (9 marks/markah)

5 SCES3110/SCEP3110/05 5. (a) Describe the physical properties and the industrial use of the carbon allotropes (diamond and graphite) and 2 other forms of carbon (activated, carbon black or coke) Terangkan ciri fisikal dan kegunaan industri alotrop karbon (diamond dan grafit) dan 2 bentuk karbon (karbon teraktif, karbon hitam atau kok) Describe briefly why Si does not react with acid or base at room temperature. At 300 o C Si can react with chlorine or bromine while at 1400 o C Si can react with nitrogen. Write all the above reactions and the products involved. yatakan dengan ringkas mengapa Si tidak bertindak balas dengan asid atau bes pada suhu bilik. Pada suhu 300 o C Si Si bertindak balas dengan klorin or bromin mana kala pada 1400 o C Si boleh bertindak balas dengan nitrogen. Tuliskan semua tindak balas di atas dan hasil yang terlibat. (c) Silicon carbide is well known for its abrasive power. It can resist any attack from most aqueous acids, however sensitive to molten hydroxide and chlorine. Explain these activities and write the reactions involved. Silikon karbid terkenal dengan kuasa abrasifnya, boleh menahan daripada bertindak balas dengan kebanyakan asid akueus, walau bagaimana pun peka kepada hidroksid lebur dan klorin. Terangkan kereaktifan dan berikan tindak balas yang terlibat. (19 marks/markah)

6 SCES3110/SCEP3110/06 Answer ALL questions. Jawab SEMUA soalan. PART/BAHAGIA B (35 marks/markah) 6. (a) Derive the rate law for the substitution of dinitrogen ligand in trans- Mo( 2 ) 2 (dppe) 2 : Terbitkan hukum kadar bagi penukargantian ligand dinitrogen dalam trans- Mo( 2 ) 2 (dppe) 2 : k 1 Mo( 2 ) 2 (dppe) 2 === Mo( 2 )(dppe) slow step/langkah k -1 perlahan slow step k 2 Mo( 2 )(dppe) 2 + CH 3 C Mo( 2 )(dppe) 2 CH 3 C Mo( 2 )(dppe) 2 CH 3 C + CH 3 C Mo(dppe) 2 (CH 3 C) 2 fast dppe = diphenylphosphinoethane The rate constant for the substitution of inner-sphere water molecules for V 2+ is about 100 s -1. Account for the magnitude of the rate constant. Pemalar kadar bagi penukargantian molekul air sfera bagi V 2+ ialah 100 s - 1. Beri penjelasan mengenai magnitud pemalar kadar ini. (c) Describe the outer sphere mechanism for electron transfer reactions. Huraikan mekanisme sfera luar bagi tindakbalas pemindahan elektron Would you expect electron exchange to take place via the outer sphere or the inner sphere mechanism between the two complexes? Give your reasons. Adakah anda menjangka penukaran elektron mengambil tempat melalui mekanisme sfera luar atau sfera dalam diantara keduadua kompleks? Beri sebab-sebab anda. [Cr(H 2 O) 6 ] 2+ + [Co(en) 3 ] 3+

7 SCES3110/SCEP3110/07 (d) Describe what is meant by the trans effect? Huraikan apa yang dimaksudkan dengan kesan trans Outline the preparation of cis- and trans-[pt(py)(br)(cl) 2 ] Trans effect series: Br - > Cl - > py (pyridine) Gariskan penyediaan cis- dan trans-[pt(py)(br)(cl) 2 ] Kesan siri trans: Br - > Cl - > py (piridin) (e) For the hydrolysis reaction: Bagi tindakbalas hidrolisis: [Co(H 3 ) 5 X] 2+ + H 2 O = [Co(H 3 ) 5 (H 2 O)] 2+ + X - Where X = I, Br, Cl and F. dimana X = I, Br, Cl and F The k obs for the reaction follows the following trend: I > Br > Cl >F. Account for this trend and state the most likely mechanism for the reaction. K obs tindakbalas mematuhi trend berikut: I > Br > Cl >F. Beri penjelasan bagi trend ini dan tentukan mekanisme yang paling mungkin bagi tindakbalas ini. (f) Answer one question only. Jawab satu soalan sahaja. Write an account of the inner sphere mechanism. Tuliskan satu rencana mengenai mekanisme sfera dalam. What are the factors involved in determining the mechanism of substitution reactions at tetrahedral sites. Apakah faktor-faktor yang terlibat dalam menentukan mekanisme tindakbalas pada kedudukan tetrahedron? (10 marks/markah) *************************