Reactions of FeIII with LiAlH4 and LiBH4 in the presence of bis(diphenylphosphino)methane (dppm) and CO. The crystal and molecular structures of trans-[Fe(Cl)(CO)(η2-dppm)2] [FeCl4], trans-Fe(H)2(η2-dppm)2 and cis-[Fe(η2-S2CH(η2-dppm)2]BF4

Synthesis and Characterization of a Terminal Iron(II)-PH2 Complex and a Series of Iron(II)-PH3 Complexes

Reported is the reaction of a series of iron(II) bisphosphine complexes with PH3 in the presence of NaBArF4 [where BArF4 = tetrakis(3,5-bis(trifluoromethyl)phenyl)borate]. The iron(II) bisphosphine reagents bear two chlorides or a hydride and a chloride motif. We have isolated six different cationic terminal-bound PH3 complexes and undertaken rigorous characterization by NMR spectroscopy, single crystal X-ray diffraction, and mass spectrometry, where the PH3 often remains intact during the ionization process. Unusual bis- and tris-PH3 complexes are among the compounds isolated. Changing the monophosphine from PH3 to PMe3 results in the formation of an unusual Fe7 cluster, but with no PMe3 being ligated. Finally, by using an iron(0) source, we have provided a rare example of a terminally bound iron-PH2 complex.

Coordination mode and stability of the tetrahydroborate ligand in group 10 metal pincer complexes

The coordination mode of the BH₄^- ligand in transition metal tetrahydroborate complexes is mainly dominated by the nature of the metal centres. However, other factors can also play important roles sometimes. In order to rationalize the coordination modes and the stability of the BH₄^- ligand in group 10 metal tetrahydroborate pincer complexes, [2,6-(^tBu₂PO)₂C₆H₃]Pt(η¹-HBH₃) and [C₆H₄-o-(NCH₂P^tBu₂)₂B]M(η²-H₂BH₂) (M = Ni, Pt) were prepared and characterized. A structural comparison of [2,6-(^tBu₂PCH₂)₂C₆H₃]Ni(BH₄), [2,6-(^tBu₂PO)₂C₆H₃]M(BH₄) and [C₆H₄-o-(NCH₂P^tBu₂)₂B]M(BH₄) (M = Ni, Pd, and Pt) indicates that the M-P bond length, the P-M-P bite angle and the trans-influence of the central atom in the pincer platform also affect the coordination mode of the BH₄^- ligand. The nickel complexes tend to adopt a monodentate coordination mode while the palladium and platinum complexes can adopt either the monodentate or the bidentate mode depending on the structural features of the pincer platforms. Longer M-P bonds and smaller P-M-P bite angles favour the bidentate mode. The stability of the BH₄^- ligand is influenced by both the coordination mode and the nature of the metal centre. The BH₃ species is released more easily from complexes with less electron rich metal centres. Following the series of Ni, Pd, and Pt, complexes with the same pincer ligand more easily lose a BH₃ moiety.

Transformation of the hydride-containing dinitrosyl iron complex [(NO)2Fe(η2-BH4)]− into [(NO)2Fe(η3-HCS2)]−via reaction with CS2

Hydride-insertion reactivity of DNIC [(NO)₂Fe(η²-BH₄)]⁻ promotes the reductive transformation of CS₂ into DNIC [(NO)₂Fe(η³-HCS₂)]⁻ featuring Fe 3d_z2-to-HCS₂ π* backbonding interaction.

High pressure studies on bis(l-histidinate)nickel(II) monohydrate

Raman spectra of bis(l-histidinate)nickel(II) monohydrate crystal were obtained for pressures up to 9.5GPa. Our results show the disappearance of some of the Raman modes and the appearance of other modes. These modifications evidence that the sample undergoes phase transitions at around 0.8 and 3.2GPa. The role played by the Ni ions and hydrogen bonds in the dynamics of the phase transitions is discussed. Under decompression, down to atmospheric pressure, the original Raman spectra are recovered, showing that both phase transitions are fully reversible.

Insertion of CS2into the Mg–H bond: synthesis and structural characterization of the magnesium dithioformate complex, [TismPriBenz]Mg(κ2-S2CH)

Insertion of CS₂into the Mg–H bond of [Tism^PriBenz]MgH affords [Tism^PriBenz]Mg(κ²-S₂CH), the first structurally characterized magnesium dithioformate compound.

Unexpected proline coordination in the copper chain polymer [Cu(μ-Cl)₂(μ-DL-proline-κ²O:O')]¹∞

In catena-poly[copper(II)-di-μ-chlorido-μ-proline-κ(2)O:O'], [CuCl2(C5H9NO2)]n, two symmetry-independent metal cations adopt distorted octahedral coordination, typical for d(9) Jahn-Teller systems. Each chloride bridge is involved in both a short and a very long interaction with a Cu(II) centre. The centrosymmetric crystal structure contains homochiral chains of opposite handedness which extend along the shortest lattice parameter (i.e. a). The O:O'-bridging coordination mode of proline, although a common motif for such complexes in general, is remarkable for Cu(II); the vast majority of amino acid derivatives of this cation are characterized by N,O-chelation.

Metal-ligand cooperation in H2 activation with iron complexes bearing hemilabile bis(diphenylphosphino)amine ligands

The octahedral transition-metal complex [(dppa)Fe(Ph2P-N-PPh2)2] (1) [dppa = bis(diphenylphosphino)amine] with homofunctional bidentate ligands is described. The ligand exhibits hemilability due to its small bite angle and the steric repulsion of the coordinated donor groups. As the {Ph2P-N-PPh2}(-) ligand can act as an internal base, heterolytic cleavage of dihydrogen by complex 1 leads to the formation of the hydride complex [(dppa)(Ph2P-N-PPh2)Fe(H)(κ(1)-Ph2P-NH-PPh2)2] (2), representing an example of cooperative bond activation with a homofunctional hemilabile ligand. This study demonstrates that hemilability of homofunctionalized ligands can be affected by careful adjustment of geometric parameters.

Low oxidation state iron(0), iron(I), and ruthenium(0) dinitrogen complexes with a very bulky neutral phosphine ligand

The synthesis of a series of iron and ruthenium complexes with the ligand P(2)P3(Cy), P(CH2CH2PCy2)3 is described. The iron(0) and ruthenium(0) complexes Fe(N2)(P(2)P3(Cy)) (1) and Ru(N2)(P(2)P3(Cy)) (2) were synthesized by treatment of [FeCl(P(2)P3(Cy))](+) and [RuCl(P(2)P3(Cy))](+) with an excess of potassium graphite under a nitrogen atmosphere. The Fe(I) and Ru(I) species [Fe(N2)(P(2)P3(Cy))](+) (3) and RuCl(P(2)P3(Cy)) (4) were synthesized by treatment of [FeCl(P(2)P3(Cy))](+) and [RuCl(P(2)P3(Cy))](+) with 1 equiv of potassium graphite under a nitrogen atmosphere. The cationic dinitrogen species [Fe(N2)H(P(2)P3(Cy))](+) (6) and [Ru(N2)H(P(2)P3(Cy))](+) (7) were formed by treatment of 1 and 3, respectively, with 1 equiv of a weak organic acid. The iron(II) complex Fe(H)2(P(2)P3(Cy)) (5) was also synthesized and characterized. Complexes [RuCl(P(2)P3(Cy))][BPh4], 1, 2, 3[BPh4], 4, 5, 6[BF4], and 7[BF4] were characterized by X-ray crystallography. The Fe(I) and Ru(I) complexes 3 and 4 were characterized by electron paramagnetic resonance (EPR) spectroscopy, and the Fe(I) complex has an EPR spectrum typical of a metal-centered radical.

Novel double insertion of carbon disulfide into two Ru-H bonds of [(dppm)(2)Ru(H)(2)] (dppm = Ph(2)PCH(2)PPh(2)): synthesis and crystal structure of a methanedithiolate complex

Addition of excess carbon disulfide to cis/trans-[(dppm)(2)Ru(H)(2)] results in the methanedithiolate complex [(dppm)(2)Ru(eta(2)-S(2)CH(2))] 4 via the intermediacy of cis-[(dppm)(2)Ru(H)(SC(S)H)] 2. The X-ray crystal structure of this species has been determined.