1

Abstract：

α-H abstraction andα-H migration reactions yield novel titanium complexes bearing terminal phosphinidene ligands. Via anα-H migration reaction, the phosphinidene (tBunacnac)Ti=P[Trip](CH2

tBu) was prepared by the addition of the primary phosphide LiPH[Trip] to the nucleophilic alkylidene triflato complex (tBunacnac)Ti=CHtBu(OTf), whileα-H abstraction was promoted by the addition of LiPH[Trip] to the dimethyl triflato precursor to afford(tBunacnac)Ti=P[Trip](CH3). Treatment of (tBunacnac)Ti=P[Trip](CH3) with B(C6F5)3 induces methide abstraction concurrent with formation of the first titanium phosphinidene zwitterion complex (tBunacnac)Ti=P[Trip]{CH3B(C6F5)3}. These titanium(IV) phosphinidene complexes possess the shortest Ti=P bonds reported, have linear phosphinidene groups, and reveal significantly upfielded solution 31P NMR spectroscopic resonances for the phosphinidene phosphorus. Solid state 31P NMR spectroscopic data also corroborate with all three complexes possessing considerably shielded chemical shifts for the linear and terminal phosphinidene functionality. In addition, high-level DFT studies on the phosphinidenes suggest the terminal phosphinidene linkage to be stabilized via a pseudo Ti≡P bond. In addition, we demonstrate that this zwitterion is a powerful phospha-Staudinger reagent and can therefore act as a carboamination precatalyst of diphenylacetylene with aldimines.

2

Neutral and Zwitterionic Low-Coordinate Titanium Complexes Bearing the Terminal Phosphinidene Functionality. Structural, Spectroscopic, Theoretical, and Catalytic Studies Addressing the Ti-P Multiple Bond

演講者 :李光凡

Guangyu Zhao, Falguni Basuli, Uriah J. Kilgore, Hongjun Fan, Halikhedkar Aneetha, John C. Huffman, Gang Wu, and Daniel J. Mindiola*

J. Am. Chem. Soc. 2006, 128 , 13575-13585.

3

Structures of The Phosphinidene Transition Metal Complexes

LnM＝ PR

M ＝ Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Ru, Os,Co, Rh, Ir L ＝ CO, PH3, Cp

D. W. Stephan, J. Am. Chem. Soc. 1995, 117, 11914.

J. Am. Chem. Soc. 2004, 126, 1924–1925.

Angew. Chem. Int. Ed. 2004, 43, 984–988.

4Mindiola, D. J. J. Am. Chem. Soc. 2003, 34, 10170-10171.

Four-Coordinate Phosphinidene Complexes of Titanium

(R- = Cy, Trip; Cy = C6H11, Trip = 2,4,6- iPr3C6H2 )

R＝ Cy (a) ； R＝ Trip (b)

76% yield 89% yield

Red-brown Orange-brown

5Mindiola, D. J. J. Am. Chem. Soc. 2003, 34, 10170-10171

Formation of Four-Coordinate Phosphinidene Complexes of Titanium

Phospha-Staudinger rearrangement

a, b

6

Formation of (tBunacnac)Ti=P[Trip](CH2tBu)

1

62% yieldSteric effect

(Ar = 2,6-iPr2C6H3, Trip = 2,4,6-iPr3C6H2)

31P NMR solution spectra of compound 1 of δ＝ 157 ppm (highly shield)

Steric effect

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Crystal Structure of Compound 1

Ti(1)=P(38) bond ＝ 2.157(2) Å

Ti(1)-C(55) bond ＝ 2.107(3) Å

Ti(1)-N(2) bond ＝ 1.981(3) Å

Ti(1)-N(6) bond ＝ 2.114(3) Å

Ti(1)-C(3) bond ＝ 2.638(4) Å

Ti(1)=P-C(40) angle ＝ 176.64(7)°

理論值 = 2.288 Å

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Preparation of Zwitterionic Low-Coordinate Titanium Complexes

Oxidation

59% yield

31P NMR solution spectra of compound 3 of δ= 232 ppm

31P NMR solution spectra of compound 4 of δ= 207 ppm

Transmetalation

α- H abstractionMethide abstraction

71% yield

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Crystal Structure of Compound 3

Ti(1)=P(39) bond ＝ 2.1644(7) Å

Ti(1)-C(55) bond ＝ 2.155(2) Å

Ti(1)-N(2) bond ＝ 2.036(6) Å

Ti(1)-N(6) bond ＝ 2.014(6) Å

Ti(1)=P(39)-C(40) angle ＝ 159.95(7)°

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Crystal Structure of Compound 4

Ti(1)=P(39) bond ＝ 2.1512(4) Å

Ti(1)-C(55) bond ＝ 2.405(3) Å

Ti(1)-N(2) bond ＝ 2.042(1) Å

Ti(1)-N(6) bond ＝ 1.973(1) Å

Ti(1)-C(3) bond ＝ 2.677(3) Å

Ti(1)-C(5) bond ＝ 2.555(3) Å

Ti(1)-C(4) bond ＝ 2.606(4) Å

Ti(1)=P(39)-C(40) angle ＝ 176.03(5)°

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1.Compound 4 have the pseudo Ti≡P bond when compared to compound 3

2.There are weak interaction between the Ti(IV) and NCCCN ring

1 3 4

Comparison of Compound 1、 3、 4

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在固態光譜中，主要導致光譜線型寬化是由於偶極作用力和各向異性化學位移 (anisotropic

chemical shift) ，這兩項作用力中都包含了 (3cos2θ-1)項。液態中，分子快速旋轉，空間

分量平均為零。固態中，則將樣品置於 NMR 轉子 (rotor)內，讓轉子沿著與外加磁場方向

θ=54.74°快速旋轉，使 (3cos2θ-1)項為零，平均掉各向異性的化學位移 (isotropic

chemical shift)，保留各向同性的峰 (isotropic peak)，同時使偶極作用力減到最小。如此可

以得到對稱性佳且線寬窄小的峰，這個角度也就是所謂的魔角。

Solid State 31P MAS NMR Spectroscopy

國立中山大學化學研究所碩士論文 ,黃玄昇 ,2003,1-83

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Chemical Shift Anisotropy Interaction

14Angew. Chem. Int. Ed. 2002, 41, 3096 - 3129

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Solid-State 31P MAS NMR Spectra

3

4

1

8.737 kHz spinning

15 kHz spinning

14 kHz spinning

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Compound 1

Compound 3

Compound 4

31P NMR 157 ppm 232 ppm 207 ppm

Solid state 31P NMR

137 ppm 220 ppm 202 ppm

Comparison of 31P NMR & Solid state 31P NMR

20ppm 12ppm 5ppm

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What is DFT

• Density-functional theory (DFT) offers a powerful and elegant method for calculating the ground-state total energy and electron density of a system of interacting electrons.

Software: Jaguar 5.5 suite

Functional: B3LYP

Basis set: 6 - 31G**

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Compound 1 of The Full Model

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Compound 3 of The Full Model

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Compound 4 of The Full Model

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a) Weather the Ti-P linkage is a double bond or a pseudo triple bond ?

b) Why in compound 1 and compound 4 the Ti-P-C is linear, while in compound 3 it signifantly bends (158.5°) ?

Full Models Versus Simplified Models

compound 1 compound 3 compound 4

atoms full simplified full simplified full simplified

metrical parameter

Ti(1)-P(2) 2.151 2.24 2.169 2.26 2.126 2.24

Ti(1)-P(2)-C(6)

175.9 106.4 158.5 95.9 178.2 68.5

bond order Ti(1)-P(2) 2.11 1.87 2.06 1.76 2.26 1.81

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Computed Frontier Orbitals

HOMO-1

HOMO

LUMO

1 3 4

P

Ti

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Reactivity of the Phosphinidene Zwitterion

4>90% yeild

[2 + 2] cycloaddition

31P NMR and 13C NMR31P NMR δ ＝ -63.3 ppm

JP-H ＝ 221.9 Hz

PhCCPh

-PhCCPh

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Catalytic Hydrophosphination

73% yield

Metathesis

1,2-insertion

α-H abstraction

α-H abstraction

protonation

25

Preparation of α,β-Unsaturated Imines

4

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Catalytic Carboamination of Diphenylacetylene

Phospha-Staudinger

1,2- insertion

~70%

insertion

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Conclusions

• Kinetically stable, neutral and zwitterionic phosphinidene complexes of titanium(IV) have been prepared.

• The phosphinidene complexes contain exceedingly short Ti=P distances, linear Ti-P-Cipso linkages, and highly shielded 31P NMR resonances.

• Zwitterionic titanium complex possessing a terminal phosphinidene functionality can deliver the phosphinidene group in a catalytic fashion togenerate the secondary vinylphosphine HP[Ph]PhC=CHPh.

• The first time that an early-transition M=P functionality can play a vital role in attractive catalytic processes such as the intermolecular hydrophosphination and carboamination of diphenylacetylene.