Preparation, properties, and reactions of metal-containing heterocycles. 58. Cyclocotrimerization of methylthioxophosphorane with alkynes

et al. 2011

Inorg. Chem.

mentioning

confidence: 76%

A Thiophosphinidene Complex as a Vehicle in Phosphinidene Transmetalation: Easy Formation and Cleavage of a P–S Bond

et al. 2011

Inorg. Chem.

“…Phosphinidene chalcogenides are isolobal-related to singlet carbenes, as first pointed out by Schoeller and Niecke, and, as it is the case of carbenes, substantial stabilization of these unsaturated molecules can be achieved through coordination to metal centers, a strategy that might allow for a more detailed study of their chemical behavior. However, in spite of the rich variety of coordination modes available for these molecules, only a very limited number of complexes have been described in the literature so far, and their chemical behavior has been little explored, if we except the reactions of the thiophosphinidene complex [Mn 2 (CO) 9{ (μ-κ 2 P,S :κ 1 P -SP(Me)}] with alkynes . Our own interest in the chemistry of chalcogenophosphinidene complexes was stimulated by the rich chemical behavior displayed by the anionic oxophosphinidene complex [MoCp(P(O)Mes*}(CO) 2 ] − (Mes* = 2,4,6-C 6 H 2 t Bu 3 ; Cp= η 5 -C 5 H 5 ), a molecule exhibiting unique acid–base and redox properties with a multisite reactivity located at their O, P and Mo atoms, depending on the reagent used.…”

Section: Introductionmentioning

confidence: 99%

Dimolybdenum Cyclopentadienyl Complexes with Bridging Chalcogenophosphinidene Ligands

et al. 2012

Inorg. Chem.

The reactions of the phosphinidene-bridged complex [Mo(2)Cp(2)(μ-PH)(η(6)-HMes*)(CO)(2)] (1), the arylphosphinidene complexes [Mo(2)Cp(2)(μ-κ(1):κ(1),η(6)-PMes*)(CO)(2)] (2), [Mo(2)Cp(2)(μ-κ(1):κ(1),η(4)-PMes*)(CO)(3)] (3), [Mo(2)Cp(2)(μ-κ(1):κ(1),η(4)-PMes*)(CO)(2)(CN(t)Bu)] (4), and the cyclopentadienylidene-phosphinidene complex [Mo(2)Cp(μ-κ(1):κ(1),η(5)-PC(5)H(4))(η(6)-HMes*)(CO)(2)] (5) toward different sources of chalcogen atoms were investigated (Mes* = 2,4,6-C(6)H(2)(t)Bu(3); Cp = η(5)-C(5)H(5)). The bare elements were appropriate sources in all cases except for oxygen, in which case dimethyldioxirane gave the best results. Complex 1 reacted with the mentioned chalcogen sources at low temperature, to give the corresponding chalcogenophosphinidene derivatives [Mo(2)Cp(2){μ-κ(2)(P,Z):κ(1)(P)-ZPH}(η(6)-HMes*)(CO)(2)] (Z = O, S, Se, Te; P-Se = 2.199(2) Å). The arylphosphinidene complex 2 was the least reactive substrate and gave only chalcogenophosphinidene derivatives [Mo(2)Cp(2)(μ-κ(2)(P,Z):κ(1)(P),η(6)-ZPMes*)(CO)(2)] for Z = O and S (P-O = 1.565(2) Å), along with small amounts of the dithiophosphorane complex [Mo(2)Cp(2)(μ-κ(2)(P,S):κ(1)(S'),η(6)-S(2)PMes*)(CO)(2)], in the reaction with sulfur. The η(4)-complexes 3 and 4 reacted with sulfur and gray selenium to give the corresponding derivatives [Mo(2)Cp(2)(μ-κ(2)(P,Z):κ(1)(P),η(4)-ZPMes*)(CO)(2)L] (L = CO, CN(t)Bu), obtained respectively as syn (Z = Se; P-Se = 2.190(1) Å for L = CO) or a mixture of syn and anti isomers (Z = S; P-S = 2.034(1)-2.043(1) Å), with these diastereoisomers differing in the relative positioning of the chalcogen atom and the terminal ligand at the metallocene fragment, relative to the Mo(2)P plane. The cyclopentadienylidene compound 5 reacted with all chalcogens, and gave with good yields the chalcogenophosphinidene derivatives [Mo(2)Cp(μ-κ(2)(P,Z):κ(1)(P),η(5)-ZPC(5)H(4))(η(6)-HMes*)(CO)(2)] (Z = S, Se, Te), these displaying in solution equilibrium mixtures of the corresponding cis and trans isomers differing in the relative positioning of the cyclopentadienylic rings with respect to the MoPZ plane in each case. The sulfur derivative reacted with excess sulfur to give the dithiophosphorane complex [Mo(2)Cp(μ-κ(2)(P,S):κ(1)(S'),η(5)-S(2)PC(5)H(4))(η(6)-HMes*)(CO)(2)] (P-S = 2.023(4) and 2.027(4) Å). The structural and spectroscopic data for all chalcogenophosphinidene complexes suggested the presence of a significant π(P-Z) bonding interaction within the corresponding MoPZ rings, also supported by Density Functional Theory calculations on the thiophosphinidene complex syn-[Mo(2)Cp(2)(μ-κ(2)(P,S):κ(1)(P),η(4)-SPMes*)(CO)(3)].

“…R–P=Z molecules can be considered isolobal with singlet carbenes,3 and might be analogously stabilized through coordination to metal centres, a strategy that could allow for a more detailed study of the chemical behaviour of these unsaturated molecules. However, only a limited number of complexes have been described in the literature thus far,4 and their chemical behaviours have been only marginally explored 5…”

Section: Introductionmentioning

confidence: 99%

Site‐Selectivity in the Protonation and Related Reactions of Chalcogenophosphinidene‐Bridged Dimolybdenum Cyclopentadienyl Complexes

et al. 2013

Eur J Inorg Chem

Reactions of the chalcogenophosphinidene‐bridged complexes syn‐[Mo2Cp2(μ‐κ2P,Z:κ1P,η4‐ZPMes*)(CO)2L] (L = CO, CNtBu; Z = O, S, Se), anti‐[Mo2Cp2(μ‐κ2P,S:κ1P,η4‐SPMes*)(CO)2L] (L = CO, CNtBu) and [Mo2Cp2{μ‐κ2P,Z:κ1P‐ZPH}(η6‐HMes*)(CO)2] (Z = S, Se, Te) towards sources of H+, Me+, and AuP(pTol)3+ cations were investigated (Mes* = 2,4,6‐C6H2tBu3; Cp = η5‐C5H5). The latter two electrophiles invariably added to the chalcogen atom to give corresponding derivatives [Mo2Cp2{μ‐κ2P,Z:κ1P,η4‐Mes*PZ(CH3)}(CO)3]BX4 [X = F, Z = O, S, Se; P–S 2.144(1) Å when Z = S and X = Ar′ = 3,5‐C6H3(CF3)2], [Mo2Cp2{μ‐κ2P,Z:κ1P,η4‐Mes*PZ(CH3)}(CNtBu)(CO)2]BF4 (Z = S, Se), and [AuMo2Cp2(μ3‐κ1S:κ2P,S:κ1P,η4‐SPMes*){P(pTol)3}(CO)3]PF6 [P–S 2.113(2), S–Au 2.320(2) Å]. Even when syn and anti isomers of the neutral precursor were used, the corresponding products were invariably characterized by their syn conformation (Z atom close to L ligand). Besides this, methylated derivatives of the chalcogenophosphinidene complexes bearing the formula [Mo2Cp2{μ‐κ2P,Z:κ1P‐HPZ(Me)}(η6‐HMes*)(CO)2](CF3SO3) (Z = S, Se, Te), were found in solution to exist as an equilibrium of corresponding cis and trans isomers differing, in each case, in the relative positioning of the Cp rings with respect to the MoPZ plane. In contrast to the above results, the protonation of all these compounds was quite sensitive to the particular chalcogenophosphinidene ligand and conformation of the complex. Protonation of the HPZ‐bridged complexes led to complex mixtures of products that could not be isolated or properly characterized. In contrast, the aryl‐bearing substrates reacted selectively to give corresponding complexes [Mo2Cp2{μ‐κ2P,Z:κ1P,η5‐ZP(C6H3tBu3)}(CO)3]BX4 (Z = S, X = F; P–S 2.032(2) Å when X = Ar′; Z = Se, X = F) and [Mo2Cp2{μ‐κ2P,Z:κ1P,η5‐ZP(C6H3tBu3)}(CNtBu)(CO)2]BAr′4 (Z = S, Se). The reaction of anti‐[Mo2Cp2(μ‐κ2P,S:κ1P,η4‐SPMes*)(CO)3] with HBF4·OEt2 at 213 K initially gave unstable intermediate anti‐[Mo2Cp2{μ‐κ2P,S:κ1P,η4‐Mes*PS(H)}(CO)3]BF4, which then rapidly converted at room temperature to the conventional isomer with the S atom close to the metallocene‐bound carbonyl ligand (syn isomer). This transformation is in agreement with Density Functional Theory calculations for neutral thiophosphinidene complexes; electrophilic attack at the sulfur atom, which is both an orbital‐ and charge‐favoured event, affords products that are more stable than those resulting from protonation at the metal sites. All these protonation reactions eventually result in an endo addition of H+ to the C6 atom of the Mes* ring with concomitant η4→η5 haptotropic shift of the resulting HMes* group. This conversion involves an easy H migration from S to the C6 atom, computed to take place with a low activation barrier of about 70 kJ/mol.