Slow Migration of a Phosphorus Ligand between Two Metal Centers

Sun, Hui; Gu, Jianli; Zhang, Zhensheng; Lin, Hai; Ding, Fei; Wang, Qiuchang

doi:10.1002/anie.200702234

Cited by 10 publications

(11 citation statements)

References 34 publications

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“…33. 11,71-75 m-PR 3 complexes have also been postulated as intermediates in the migration of PR 3 ligands between two metal centres, 76 and closely related m-phosphole derivatives of Pd, 77,78 Pt, 77,79 Cu, 77,80 and Ag 81 have also been synthesized (Fig. 34).…”

Section: Class II L-l 3c-2e Bondsmentioning

confidence: 99%

The occurrence and representation of three-centre two-electron bonds in covalent inorganic compounds

2012

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Although compounds that feature 3-centre 2-electron (3c-2e) bonds are well known, there has been no previous effort to classify the interactions according to the number of electrons that each atom contributes to the bond, in a manner analogous to the classification of 2-centre 2-electron (2c-2e) bonds as either normal covalent or dative covalent. This article provides an extension to the Covalent Bond Classification (CBC) method by categorizing 3c-2e interactions according to whether (i) the two electrons are provided by one or by two atoms and (ii) the central bridging atom provides two, one, or zero electrons. Class I 3c-2e bonds are defined as those in which two atoms each contribute one electron to the 3-centre orbital, while Class II 3c-2e bonds are defined as systems in which the pair of electrons are provided by a single atom. Class I and Class II 3c-2e interactions can be denoted by structure-bonding representations that employ the "half-arrow" notation, which also provides a convenient means to determine the electron count at a metal centre. In contrast to other methods of electron counting, this approach provides a means to predict metal-metal bond orders that are in accord with theory. For example, compounds that feature symmetrically bridging carbonyl ligands do not necessarily have to be described as "ketone derivatives" because carbon monoxide can also serve as an electron pair donor to two metal centres. This bonding description also provides a simple means to rationalize the theoretical predictions of the absence of M-M bonds in molecules such as Fe(2)(CO)(9) and [CpFe(CO)(2)](2), which are widely misrepresented in textbooks as possessing M-M bonds.

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Section: Class II L-l 3c-2e Bondsmentioning

confidence: 99%

The occurrence and representation of three-centre two-electron bonds in covalent inorganic compounds

2012

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“…It was found that complex 7 did not undergo thermal rearrangement when refluxed in p-xylene. This result remained unchanged even after substitution of a CO ligand with P(OPh) 3 , 10 which has been well known to be able to accelerate and angles (deg): Fe(1)-Fe(2) 2.550(2), Si(1)-C(10) 1.883(3),C(10)-C(11)1.475(8),Si(1)-C(5)1.881(7);Si(1)-C(10)-C(11) 120.8(4), C(10)-Si(1)-C(5) 107.8(3).…”

Section: Resultsmentioning

confidence: 93%

“…14 Such ligand substitution would produce two regioisomers, 10′a and 10′b (Scheme 4), in nearly equal amounts that should be in fast equilibrium owing to migration of the phosphite ligand between two iron centers. 10 Their subsequent rearrangements leading to preferential formation of the trans rearranged product may be rationalized on the basis of our previously suggested mechanism of the thermal rearrangement, 8c by the fact that the initial formation of the Si-Fe bond between the phosphitesubstituted iron and the silicon should be the rate-determining step of the rearrangement process and that in this step there should be much less steric hindrance between P(OPh) 3 and SiMe 2 for the formation of the trans product than between P(OPh) 3 and SiPh 2 for the formation of the cis isomer.…”

Section: Si-si Bridged Tetracarbonyldiiron Complexesmentioning

confidence: 99%

Synthesis and Properties of Structural Variants of the Si−Si Bridged Bis(cyclopentadienyl)tetracarbonyldiiron Complexes: Modification on the Bridge

Sun

Liu

et al. 2008

Organometallics

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A series of new structural variants of the Si-Si bridged bis(cyclopentadienyl)tetracarbonyldiiron complex (η 5 ,η 5 -C 5 H 4 XC 5 H 4 )Fe 2 (CO) 4 , where X ) MeSi[µ-(CH 2 ) 4 ]SiMe (3), CH 2 SiMe 2 (7), and SiMe 2 SiPh 2 (10), were synthesized and their properties studied with emphasis on the thermal rearrangement that had been demonstrated to occur when X ) SiMe 2 SiMe 2 . It was found that the presence of the cyclic structure on the Si-Si bridge for complex 3 prohibited the thermal rearrangement, but oxygen insertion into the Si-Si bond took place under thermal conditions to give the new Si-O-Si bridged complex {η 5 ,η 5 -C 5 H 4 MeSi(µ-O)[µ-(CH 2 ) 4 ]SiMeC 5 H 4 }Fe 2 (CO) 4 (4). Using CH 2 SiMe 2 as the bridging group in complex 7 also resulted in failure of the rearrangement because the C-Si bond could not be activated by the iron center. Complex 10, with the unsymmetric bridging group SiMe 2 SiPh 2 , underwent thermal rearrangement, producing the expected product cyclic-[(Me 2 Si-η 5 -C 5 H 4 )Fe(CO) 2 (Ph 2 Si-η 5 -C 5 H 4 )Fe(CO) 2 ]-( 11) with two Si-Fe bonds. When the reaction was performed in the presence of P(OPh) 3 , incorporation of the phosphite ligand in the rearranged product took place, providing two regioisomers, cyclic-{(Me 2 Si-η 5 -C 5 H 4 )Fe(CO)[P(OPh) 3 ](Ph 2 Si-η 5 -C 5 H 4 )Fe(CO) 2 }-(12a) and cyclic-{(Me 2 Si-η 5 -C 5 H 4 )Fe(CO) 2 (Ph 2 Si-η 5 -C 5 H 4 )Fe(CO)[P(OPh) 3 ]}-(12b), in a 1:1.8 ratio. The reaction of 10 with I 2 led to Fe-Fe bond cleavage, affording di-iodide (η 5 ,η 5 -C 5 H 4 Me 2 SiSiPh 2 C 5 H 4 )[Fe(CO) 2 I] 2 (13). The molecular structures of 3, 4, 7, 10, 11, and 13 have been determined by X-ray diffraction methods.

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“…An investigation into the migration of phosphine ligands in dimeric cyclopentadienyl iron carbonyl complexes has been reported. 51 By using an unsymmetrical bridge between two metals and a thorough analysis of the activation parameters it was demonstrated that migration was not occurring via a dissociative route thus consistent with an intermediate, such as 18, containing a bridging phosphine ligand. The mechanism of the nucleophilic cleavage of the S-S bond in MeSSMe by PMe 3 has been investigated using the DFT technique: the ramifications of the results for biologically important disulfides were also examined.…”

Section: Phosphorusmentioning

confidence: 99%

Nitrogen, phosphorus, arsenic, antimony and bismuth

Lynam

2008

Annu. Rep. Prog. Chem., Sect. A: Inorg. Chem.

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This chapter reviews the literature reported during 2007 on the chemistry of nitrogen, phosphorus, arsenic, antimony and bismuth. HighlightsOnce again there has been considerable development in the chemistry of the Group 15 elements, and a notable highlight has been the continued studies by the group of Cummins into the use of early transition metal amido complexes as transfer agents for nitride, phosphide and related ligands. [1][2][3] NitrogenA review of the recent advances in the activation of N 2 by Group 4 metal complexes has been published. 4 The reaction of [(Z 5 -C 5 Me 4 H) 2 Hf] 2 (m-Z 2 :Z 2 -N 2 ) with CO 2 results in the insertion of two equivalents of CO 2 into Hf-N bonds and formation of 1. 5 Importantly, reaction of 1 with Me 3 SiI results in the ultimate formation of (Z 5 -C 5 Me 4 H) 2 HfI 2 and (Me 3 Si) 2 NN(CO 2 SiMe 3 ) 2 . Reduction of Zr[NPN]*Cl 2 with KC 8 in thf solution under an atmosphere of N 2 leads to the formation {[NPN]*Zr(THF)} 2 (m-Z 2 :Z 2 -N 2 ). 6 The N-N bond length in this species is 1.503(6) A ˚which corresponds to a formal reduction to N 2 4À. The dinitrogen complex [Me 2 Si(Z 5 -C 5 Me 4 )(Z 5 -C 5 H 3 -3-t Bu)Zr] 2 (m-Z 2 :Z 2 -N 2 ) has also been prepared and reacts with H 2 under ambient conditions to give [Me 2 Si(Z 5 -C 5 Me 4 )(Z 5 -C 5 H 3 -3-t Bu)ZrH] 2 (m-Z 2 :Z 2 -N 2 H 2 ). 7 An important feature of this chemistry is the contrast with a related dinitrogen complex which contains less electron donating cyclopentadienyl ligands. In this latter case, as there is less electron density on the N 2 it is more weakly bound to the metal and hydrogenation results in the displacement of N 2 and the formation of the corresponding zirconium dihydride. Reduction of the tantalum complex Cp*TaCl 3 (L) (L = N i PrC{Me}N i Pr) with 2.5 equivalents of KC 8 under N 2 results in the formation of the dimeric complex 2, whereas higher temperature and 4 equivalents of KC 8 result in the formation of 3: other reduction products were also obtained and fully characterised. 8 Reactions of both zirconium and hafnium complexes containing related ligand sets to this tantalum example have also been investigated. 9 A niobium hydride complex, supported by tripodal alkoxide ligands, has also been shown to react with N 2 to give a similar formal N-N cleavage. 10 Further examples of N 2 fixation at chromium, 11 titanium, 12 vanadium, 13 and samarium 14 have all been reported. A theoretical study into the design of complexes which will bind N 2 but also allow for subsequent hydrogenation has been published 15 as has a

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Slow Migration of a Phosphorus Ligand between Two Metal Centers

Cited by 10 publications

References 34 publications

The occurrence and representation of three-centre two-electron bonds in covalent inorganic compounds

The occurrence and representation of three-centre two-electron bonds in covalent inorganic compounds

Synthesis and Properties of Structural Variants of the Si−Si Bridged Bis(cyclopentadienyl)tetracarbonyldiiron Complexes: Modification on the Bridge

Nitrogen, phosphorus, arsenic, antimony and bismuth

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