E-H Bond Cleavage Processes in Reactions of Heterometallic Phosphinidene-Bridged MoRe and MoMn Complexes with Hydrogen and p-Block Element Hydrides

Reactions of complexes [MoMCp(μ-PMes*)(CO)6] with H2 and several p-block element (E) hydrides mostly resulted in the cleavage of E-H bonds under mild conditions [M = Re (1a) and Mn (1b); Mes* = 2,4,6-C6H2tBu3]. The reaction with H2 (ca. 4 atm) proceeded even at 295 K to give the hydrides [MoMCp(μ-H)(μ-PHMes*)(CO)6]. The same result was obtained in the reactions with H3SiPh and, for 1a, upon reduction with Na(Hg) followed by protonation of the resulting anion [MoReCp(μ-PHMes*)(CO)6]-. The latter reacted with [AuCl{P(p-tol)3}] to yield the related heterotrimetallic cluster [MoReAuCp(μ-PHMes*)(CO)6{P(p-tol)3}]. The reaction of 1a with thiophenol gave the thiolate-bridged complex [MoReCp(μ-PHMes*)(μ-SPh)(CO)6], which evolved readily to the pentacarbonyl derivative [MoReCp(μ-PHMes*)(μ-SPh)(CO)5]. In contrast, no P-H bond cleavage was observed in reactions of complexes 1a,b with PHCy2, which just yielded the substituted derivatives [MoMCp(μ-PMes*)(CO)5(PHCy2)]. Reactions with HSnPh3 again resulted in E-H bond cleavage, but now with the stannyl group terminally bound to M, while 1a reacted with BH3·PPh3 to give the hydride-bridged derivatives [MoReCp(μ-H)(μ-PHMes*)(CO)5(PPh3)] and [MoReCp(μ-H){μ-P(CH2CMe2)C6H2tBu2}(CO)5(PPh3)], which follow from hydrogenation, C-H cleavage, and CO/PPh3 substitution steps. Density functional theory calculations on the PPh-bridged analogue of 1a revealed that hydrogenation likely proceeds through the addition of H2 to the Mo=P double bond of the complex, followed by rearrangement of the Mo fragment to drive the resulting terminal hydride into a bridging position.

Investigating the structural chemistry of organotin(IV) compounds: recent advances

Organotin(IV) compounds have been considered for their outstanding industrial, medical and specific applications in the synthesis of various types of chemical compounds. In this review, we have focused on the structural chemistry of organotin(IV) compounds, including coordination chemistry, the effect of structure on reactions, bond formations from the perspective of structure and investigation of the structure of organotin(IV) compounds in different phases. The structural chemistry of organotin(IV) compounds is subject to interest due to their major impact on predicting the properties and drumming up support for pushing back the frontiers of synthesis of organotin(IV) compounds with advanced properties.

Phosphinidene-Bridged MoMn Derivatives of the Thiophosphinidene Complex [Mo2Cp2(μ-κ2:κ1,η6-SPMes*)(CO)2] (Mes* = 2,4,6-C6H2tBu3)

The title complex (1) reacted with [Mn₂(CO)₁₀] under visible-UV irradiation (toluene solution and quartz glassware) to give a mixture of the phosphinidene complex [MnMoCp(μ-κ¹:κ¹,η⁶-PMes*)(CO)₄], the cluster [Mn₂Mo₂Cp₂(μ-κ¹:κ¹,η⁶-PMes*)(μ₃-S)(CO)₈], and the thiophosphinidene complex [MnMoCp(μ-κ²:κ¹,η⁴-SPMes*)(CO)₅], in yields of ca. 60, 20, and 10% respectively (Mes* = 2,4,6-C₆H₂^tBu₃). The major product follows from formal replacement of the SMoCp(CO)₂ fragment in 1 with a Mn(CO)₄ fragment, and displayed multiple bonding to phosphorus (Mn-P = 2.1414(8) Å); the tetranuclear cluster results from formal insertion of a Mn₂(CO)₆ fragment in 1, with cleavage of P-S and P-Mo bonds, to render a μ₃-S bridged Mn₂Mo core bearing an exocyclic phosphinidene ligand involved in multiple bonding to one of the Mn atoms (Mn-P = 2.140(2) Å); the thiophosphinidene complex (Mn-P = 2.294(1) Å) formally results from addition of sulfur and carbon monoxide to the major MnMo product, a transformation which actually could be performed stepwise, via the MnMo thiophosphinidene complex [MnMoCp(μ-κ²:κ¹,η⁶-SPMes*)(CO)₄]. When the photolysis of 1 and [Mn₂(CO)₁₀] was performed in tetrahydrofuran solution and using conventional glassware, then the V-shaped cluster [Mn₂MoCp{μ-κ¹:κ¹:κ¹,η⁵-P(C₆H₃^tBu₃)}(CO)₈] was obtained selectively (Mo-Mn = 3.2910(5) Å, Mn-Mn = 2.9223(5) Å), which unexpectedly displays a cyclohexadienylidene-phosphinidene ligand resulting from H atom abstraction at the aryl ring of the precursor. Density functional theory calculations on the complexes [L_nM(μ-κ¹:κ¹,η⁶-PMes*)MoCp] (ML_n = MoCp(CO)₂, Mn(CO)₄, Co(CO)₃) revealed that the degree of delocalization of the metal-phosphorus π-bonding interaction over the Mo-P-M chain is significantly conditioned by the heterometal fragment ML_n, it being increased in the order Mn ≤ Mo < Co.