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第 9 章 金属原子簇和金属金属多重键 PowerPoint PPT Presentation


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第 9 章 金属原子簇和金属金属多重键. 存在 M - M 键的化合物称为簇合物( cluster) (M 为 3 以上) 羰基原子簇 : Rh 6 (CO) 16 , Co 4 (CO) 12 ( 0 价)( 低价 ) 卤化物类原子簇 : Mo 6 Cl 8 4+ ( +2 价) ( 高价 ). 一 金属原子簇. Carbonyl Cluster 低核羰基原子簇 (Low Nuclear Carbonyl Cluster ) : 18 电子规则.

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第 9 章 金属原子簇和金属金属多重键

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第9章 金属原子簇和金属金属多重键

存在M-M键的化合物称为簇合物(cluster) (M为3以上)

羰基原子簇:Rh6(CO)16, Co4(CO)12(0价)(低价)

卤化物类原子簇: Mo6Cl84+ (+2价) (高价)


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一 金属原子簇

  • Carbonyl Cluster

  • 低核羰基原子簇(Low Nuclear Carbonyl Cluster ) :

    18电子规则

Fe3(CO)10(–CO)2 M3(CO)12


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M4(CO)9(-CO)3 Ir4(CO)12


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  • Medium size Carbonyl Cluster

M6(CO)12(3–CO)4

不符合18电子规则(18 )


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Wade规则: For Medium size Carbonyl Cluster M(CO)3与BH(或CH)的等瓣关系,

PSEPT (多面体骨架电子数理论) , (v+ x-12)

(2n+2)、 (2n+4)、(2n+6)骨架电子数规则

TEC(总电子数)方法

(9N-L)规则

(nxc)规则


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Wade规则:M(CO)3与BH(或CH)的等瓣关系,

PSEPT (Polyhedral Skeletal Electron Pair Theory)多面体骨架电子数理论

分子片的骨架电子数(v+ x-12)

v为中心金属的价电子数, x为配体提供的总电子数

(2n+2)、 (2n+4)、(2n+6) 骨架电子数规则

or (n+1)、 (n+2)、 (n+3)骨架电子对数规则

闭式、 开式、 网式


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一个Co(CO)2分子片的骨架电子数:

v=9

x=22=4

(v+x-12)=1

6个Co(CO)2分子片

1 6=6

4个CO=8

总骨架电子数=6+8=14

总骨架电子对数=7=6+1

n+1 闭式结构

或者:

TEC=6 9+16 2=86

总骨架电子数=86-12 6=14

骨架电子对数=7


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Fe5(CO)15C

一个Fe(CO)3分子片的骨架电子数:

v=8

x=32=6

(v+x-12)=2

5个Fe(CO)3分子片

2 5=10

1个=4

总骨架电子数=10+4=14

总骨架电子对数=7=5+2

n+2 开式结构

或者:

TEC=5 8 +2 15 + 4

=74

总骨架电子数=74-12 5

=14

骨架电子对数=7


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  • High-Nuclear Carbonyl Cluster:

若按照 Wade 规则计算

骨架电子数=14

不符合Wade规则

An Unprecedented High-Nuclearity Closest-Packed

Bimetallic Palladium Carbonyl Cluster:

[Pd33Ni9(CO)41(PPh3)6]4-Containing a Pseudo-D3h

hcp Pd33Ni9 Core

J. Am. Chem. Soc. 1996, 118, 7869-7870


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The 41 CO consist of 5 terminal and 36 bridging ligands. The terminal COs are coordinated to the three corner Ni atoms in the middle layer and to the two central Pd atoms in the top and bottom layers. Of the 36 bridging COs, 24 are edgebridging and the other 12 are face-bridging.

Pd6

Pd7Ni3


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2. 高价过渡金属卤化物(硫化物)原子簇

M6X8 或[ M6(3-X)8 ]

Mo6Cl84+ Mo6S84 –

Mo(II) 簇电子数: 4×6 = 24e

Mo—Mo间的电子数: 24/12(棱)=2

Mo—Mo 单键(2e) ~ 2.60Å


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Chevrel phase, PbM6S8


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高价过渡金属卤化物原子簇M6X12

Nb6Cl122+

Nb(氧化态=14/6) 簇电子数: (5 –14/6)×6 =16e

(或者 簇电子数=5×6 –12-2=16)

Nb—Nb间的电子数: 16/12(棱)=4/3e

Nb—Nb 键级: 2/3 ~ 2.90Å


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Synthesis and Structural Characterization of Compounds Containing the [Zr6Cl18H5]3-

Cluster Anion. Determination of the Number of Cluster Hydrogen Atoms

Linfeng Chen, F. Albert Cotton,* and William A. Wojtczak

Inorg. Chem. 1997, 36, 4047-4054

注意结构的对称性!


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3. 过渡金属-硫“原子簇”

Fe4S4基本单元

[Fe4S4(SPh)4]2-结构


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Fe4S*4Cys4n-

生物体内的电子转移反应

Fe4S43++e-  Fe4S42+ +e-  Fe4S4+

Fe33+,Fe2+ /Fe23+,Fe22+ / Fe3+, Fe32+


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Schematic structures

(A) a proposed 6-Fe cluster in [Fe]-hydrogenase,

(B) the binuclear site in D. gigas hydrogenase,

(C) the P cluster of nitrogenase (Rees),

(D) the P cluster of nitrogenase (Bolin),

(E) the cofactor cluster of

nitrogenase,

(F) [MFe4S6(PEt3)4Cl] (M=V, Mo).


Multi bonds

二. 金属-金属多重键(multi-bonds)

1935年, C. Brosset

K3W2Cl9 中, W—W 240pm (2.40Å)

W单质中, W—W 275pm

1975年 F. A. Cotton,

Re2Cl82– (d4) Re—Re 224pm

d3

F. A. Cotton,

“Highlights From Recent Work On Metal-Metal Bonds”

Inorg. Chem. 39(1998)5710-5720


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多重键缩短比(多重键键长/单键键长)


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Re2Cl82– Cr2Ac4.2H2O

四方棱柱构形


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5个d轨道的形成的1 个2 个2个键


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dx2-y2轨道和dxy的形成2个键


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四方棱柱M-M间的d 轨道能级图


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*

*

*

M2L8四方棱柱的d轨道能级图


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[Re2Cl8]2-+ PR3

2 4 2 (4级键)

1,2,7-Re2Cl5(PMe3)3

2 4 2 *1 (3.5级键)

1,3,6,8-Re2Cl4(PMe3)4+Cl2

2 4 2 *2(3级键)

1,3,6-Re2Cl5(PMe3)3

2 4 2 *1(3.5级键)


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[Re2Cl8]2- + PMe3 (惰性气氛,苯溶剂) 1,2,5,7-Re2Cl6(PMe3)4 (+3) (+3)

2 4 2 (4级键)

Re—Re 3.8486Å 不存在金属-金属键


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[Re2Cl8]2- + PEt2H ( HCl,苯 ) 1,2,5,6-Re2Cl4(-PEt2)(PEt2H)4

(+3) (+4)


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Trinuclear complexes

di-2-pyridylamine (dpa-)

[Cr3(dpa)4Cl2]+

从高度对称到非对称


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四氰基铂酸钾K2Pt(CN)4X0.3(KCP)

一维导体(分子导线)

由Pt的5dz2轨道重叠形成导带

Pt(CN)4n-的链状分子

讨论: K2Pt(CN)4的电导很小,Pt被部分氧化后电导增大,原因?


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阴离子堆垛结构的四氰基铂酸盐


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Cu2(CH3COO)4.2H2O,是否存在Cu—Cu间的键?

Cu—Cu ~ 2.44-2.81Å

r(Cu2+)~ 0.6-0.8Å

Cu—Cu间无化学键,

磁性具有强温度相关性

eff = ~ 1.4BM/Cu atom

A.F. Cotton

Adv. Inorg. Chem. (1999).

p.870


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Binuclear complexes. I. Electronic structure of copper acetate. Forster, Leslie S.; Ballhausen, C. J. Univ. Copenhagen, Acta Chemica Scandinavica (1962), 16 1385-92. CODEN: ACHSE7 ISSN: 0904-213X. Journal written in English. CAN 57:73457 AN 1962:473457 CAPLUS

Abstract

Electronic structure of the dimeric Cu acetate Cu2(Ac)4.2H2O was considered by using a tentative mol. orbital scheme. A rather strong s bond exists between the 2 Cu units, in contrast to a former proposal of a d bond (Figgis and Martin, CA 51, 1672h). Although the proposed model gives a satisfactory qual. account of the exptl. data (antiferromagnetism, absorption spectrum, and g factors), alternative models may also be consistent with the rather limited data.


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Dinuclear copper(II) acetate monohydrate. Redetermination of the structure by neutron-diffraction analysis. Brown, George M.; Chidambaram, R. Chem. Div., Oak Ridge Natl. Lab., Oak Ridge, TN, USA. Acta Crystallographica, Section B: Structural Crystallography and Crystal Chemistry (1973), 29(Pt. 11), 2393-403.

  Abstract

The crystal structure of dinuclear Cu(II) acetate monohydrate, Cu2(O2CCH3)4.2H2O (van Niekerk and Schoening, 1953), was refined by the full-matrix least-squares method using 3-dimensional neutron data and revised cell parameters [a 13.167 (4), b 8.563 (2), c 13.862 (7) .ANG., b 117.019 (2)° (lCu Ka1 = 1.54051 .ANG.), space group C2/c, and Z = 4]. A reasonable description of the Me groups, which are in large-amplitude torsional oscillation, was obtained by using a special model. R(F) = 0.061 and R(F2) = 0.072 for F2 > s, excluding the very weak reflections and reflections mildly affected by extinction. The intramolecular Cu-Cu vector is 2.6143 (17) .ANG. long and oriented almost exactly as reported from measurements of magnetic anisotropy and electron spin resonance


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Rhodium acetate dimer Rh2(OAc)4(H2O)2

Cu2(OAc)4L2 where L = pyridine or 0.5 pyrazine

Rh2(OAc)4(H2O)2中Rh- Rh的键级是多少?


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