Electronic Stabilization of Trigonal Bipyramidal Clusters: the Role of the Sn(II) Ions in [Pt5(CO)5{Cl2Sn(μ-OR)SnCl2}3]3– (R = H, Me, Et, iPr)

Inverted Ligand Field in a Pentanuclear Bow Tie Au/Fe Carbonyl Cluster

Gold chemistry has experienced in the last decades exponential attention for a wide spectrum of chemical applications, but the +3 oxidation state, traditionally assigned to gold, remains somewhat questionable. Herein, we present a detailed analysis of the electronic structure of the pentanuclear bow tie Au/Fe carbonyl cluster [Au{η²-Fe₂(CO)₈}₂]^- together with its two one-electron reversible reductions. A new interpretation of the bonding pattern is provided with the help of inverted ligand field theory. The classical view of a central gold(III) interacting with two [Fe₂(CO)₈]^2- units is replaced by Au(I), with a d¹⁰ gold configuration, with two interacting [Fe₂(CO)₈]^- fragments. A d¹⁰ configuration for the gold center in the compound [Au{η²-Fe₂(CO)₈}₂]^- is confirmed by the LUMO orbital composition, which is mainly localized on the iron carbonyl fragments rather than on a d gold orbital, as expected for a d⁸ configuration. Upon one-electron stepwise reduction, the spectroelectrochemical measurements show a progressive red shift in the carbonyl stretching, in agreement with the increased population of the LUMO centered on the iron units. Such a trend is also confirmed by the X-ray structure of the direduced compound [Au{η¹-Fe₂(CO)₈}{η²-Fe₂(CO)₆(μ-CO)₂}]^3-, featuring the cleavage of one Au-Fe bond.

Metal carbonyl clusters of groups 8-10: synthesis and catalysis

In this review article, we discuss advances in the chemistry of metal carbonyl clusters (MCCs) spanning the last three decades, with an emphasis on the more recent reports and those involving groups 8-10 elements. Synthetic methods have advanced and been refined, leading to higher-nuclearity clusters and a wider array of structures and nuclearities. Our understanding of the electronic structure in MCCs has advanced to a point where molecular chemistry tools and other advanced tools can probe their properties at a level of detail that surpasses that possible with other nanomaterials and solid-state materials. MCCs therefore advance our understanding of structure-property-reactivity correlations in other higher-nuclearity materials. With respect to catalysis, this article focuses only on homogeneous applications, but it includes both thermally and electrochemically driven catalysis. Applications in thermally driven catalysis have found success where the reaction conditions stabilise the compounds toward loss of CO. In more recent years, MCCs, which exhibit delocalised bonding and possess many electron-withdrawing CO ligands, have emerged as very stable and effective for reductive electrocatalysis reactions since reduction often strengthens M-C(O) bonds and since room-temperature reaction conditions are sufficient for driving the electrocatalysis.

A serendipitous isolation of cocrystallized platinum–tin complexes: synthesis, structure and theoretical exploration

An adduct of co-crystallized platinum–tin fragments has been synthesized and characterized. NBO and EDA analysis have been performed to explore the nature of bonding in fragments, especially the extent of oxophilic character present in tin atoms.

Rational Syntheses and Serendipity: Complexes [LSnPtCl2 (SMe2 )]2 , [{LSnPtCl(SMe2 )}2 SnCl2 ], [(LSn)3 (PtCl2 )(PtClSnCl){LSn(Cl)OH}], and [O(SnCl)2 (SnL)2 ] with L=MeN(CH2 CMe2 O)2

Syntheses and molecular structures of the dimeric tin-platinum complex [LSnPtCl₂ (SMe₂ )]₂ (2), the tin-platinum clusters [{LSnPtCl(SMe₂ )}₂ SnCl₂ )] (3) and [(LSn)₃ (PtCl₂ )(PtClSnCl)(LSnOHCl)] (6) (L=MeN(CH₂ CMe₂ O^- )₂ ), and of the unprecedented tin(II) aminoalkoxide-tin oxide chloride complex [O(SnCl)₂ ⋅(SnL)₂ ] (5) are reported. The compounds were characterized by NMR spectroscopy (¹ H, ¹³ C, ¹¹⁹ Sn, ¹⁹⁵ Pt), ¹¹⁹ Sn Mössbauer spectroscopy (1-3, 6), electrospray ionization mass spectrometry, elemental analyses, and single-crystal X-ray diffraction analyses (2⋅CH₂ Cl₂ , 3⋅2 C₄ H₈ O, 5, 6⋅3CH₂ Cl₂ ). The tin(II) aminoalkoxide [MeN(CH₂ CMe₂ O)₂ Sn]₂ (1) behaves like a neutral ligand, inserts into a Pt-Cl bond, or is involved in rearrangement reactions with the different behavior occurring even within one compound (3, 6). DFT calculations show that the tin-platinum compounds behave like electronic chameleons.

Heteroleptic Chini-Type Platinum Clusters: Synthesis and Characterization of Bis-Phospine Derivatives of [Pt3n(CO)6n]2- (n = 2-4)

The reactions of [Pt_3n(CO)_6n]^2- (n = 2-4) homoleptic Chini-type clusters with stoichiometric amounts of Ph₂PCH₂CH₂PPh₂ (dppe) result in the heteroleptic Chini-type clusters [Pt₆(CO)₁₀(dppe)]^2-, [Pt₉(CO)₁₆(dppe)]^2-, and [Pt₁₂(CO)₂₀(dppe)₂]^2-. Their formation is accompanied by slight amounts of neutral species such as Pt₄(CO)₄(dppe)₂, Pt₆(CO)₆(dppe)₃, and Pt(dppe)₂. A similar behavior was observed with the chiral ligand R-Ph₂PCH(Me)CH₂PPh₂ (R-dppp), and two isomers of [Pt₉(CO)₁₆(R-dppp)]^2- were identified. All the new species were spectroscopically characterized by means of IR and ³¹P NMR, and their structures were determined by single-crystal X-ray diffraction. The results obtained are compared to those previously reported for monodentate phosphines, that is, PPh₃, as well as more rigid bidentate ligands, that is, CH₂═C(PPh₂)₂ (P^P), CH₂(PPh₂)₂ (dppm), and o-C₆H₄(PPh₂)₂ (dppb). From a structural point of view, functionalization of anionic platinum Chini clusters preserves their triangular Pt₃ units, whereas the overall trigonal prismatic structures present in the homoleptic clusters are readily deformed and transformed upon functionalization. Such transformations may be just local deformations, as found in [Pt₉(CO)₁₆(dppe)]^2-, [Pt₉(CO)₁₆(R-dppp)]^2-, [Pt₁₂(CO)₂₂(PPh₃)₂]^2-, and [Pt₉(CO)₁₆(PPh₃)₂]^2-; an inversion of the cage from trigonal prismatic to octahedral, as observed in [Pt₆(CO)₁₀(dppe)]^2- and [Pt₆(CO)₁₀(PPh₃)₂]^2-; the reciprocal rotation of two trigonal prismatic units with the loss of a Pt-Pt contact as found in [Pt₁₂(CO)₂₀(dppe)₂]^2-.

Platinum carbonyl clusters stabilized by Sn(ii)-based fragments: syntheses and structures of [Pt6(CO)6(SnCl2)2(SnCl3)4]4−, [Pt9(CO)8(SnCl2)3(SnCl3)2(Cl2SnOCOSnCl2)]4−and [Pt10(CO)14{Cl2Sn(OH)SnCl2}2]2−

Low valent Pt carbonyl clusters decorated by Sn(ii) fragments have been obtained from [Pt₁₅(CO)₃₀]²⁻and SnCl₂.