Identification of a novel η2-Se2 bonding mode in Cu(I) complexes of the dimeric selenocarbonyl dianions, [(EPh2P)2CSeSeC(PPh2E)2](2-) (E = S, Se)

Molecular Bis(chalcogenido) Titanates of Te, Se, and S

A series of titanate cisoid bis(chalcogenidos) (Ch = Te, Se, and S) complexes supported by the β-diketiminate ligand BDI- = [ArNC(CH3)]2CH (Ar = 2,6-iPr2C6H3) are readily assembled via treatment of the TiIII precursor (BDI)Ti(CH2SiMe3)2 with 2.5 equiv of elemental "Ch" source and 1 equiv of reductant in the presence of crown-ether. In the absence of the electride, Te or S addition to (BDI)Ti(CH2SiMe3)2 results instead in the isolation of a mononuclear tellurido-tellurolate [(BDI)Ti(=Te)(TeCH2SiMe3)] and the bridging sulfido-thiolate complex [(BDI)Ti(SCH2SiMe3)(μ-S)]2, respectively. In the case of Se, the rare selenido-perselenoate complex [(BDI)Ti(=Se)(η2-SeSeCH2SiMe3)] was isolated. In addition to crystallographically and spectroscopically characterizing all of the complexes, we demonstrate the latter species to be likely intermediates in the formation of [(BDI)Ti(Ch)2]- via the addition of electride.

s-Block metal complexes of PC(H)P-bridged chalcogen-centred methanides: comparisons with isoelectronic PNP-bridged monoanions

This Perspective compares the chemistries of s-block metal complexes of isoelectronic PC(H)P- and PNP-bridged, chalcogen-centred monoanions with a focus on the unique behavior of the C(H)-bridged systems.

Synthesis of a labile sulfur-centred ligand, [S(H)C(PPh2S)2](-): structural diversity in lithium(i), zinc(ii) and nickel(ii) complexes

A high-yield synthesis of [Li{S(H)C(PPh2S)2}]2 [Li2·(3)2] was developed and this reagent was used in metathesis with ZnCl2 and NiCl2 to produce homoleptic complexes 4 and 5b in 85 and 93% yields, respectively. The solid-state structure of the octahedral complex [Zn{S(H)C(PPh2S)2}2] (4) reveals notable inequivalence between the Zn-S(C) and Zn-S(P) contacts (2.274(1) Å vs. 2.842(1) and 2.884(1) Å, respectively). Two structural isomers of the homoleptic complex [Ni{S(H)C(PPh2S)2}2] were isolated after prolonged crystallization processes. The octahedral green Ni(ii) isomer 5a exhibits the two monoprotonated ligands bonded in a tridentate (S,S',S'') mode to the Ni(ii) centre with three distinctly different Ni-S bond lengths (2.3487(8), 2.4500(9) and 2.5953(10) Å). By contrast, in the red-brown square-planar complex 5b the two ligands are S,S'-chelated to Ni(ii) (d(Ni-S) = 2.165(2) and 2.195(2) Å) with one pendant PPh2S group. DFT calculations revealed that the energetic difference between singlet and triplet state octahedral and square-planar isomers of the Ni(ii) complex is essentially indistinguishable. Consistently, VT and (31)P CP/MAS NMR spectroscopic investigations indicated that a mixture of isomers exists in solution at room temperature, while the singlet state square-planar isomer 5b becomes favoured at -40 °C.

1,1'-(Diselanediylbis{[P,P-diphenyl-N-(tri-methyl-sil-yl)phospho-rimido-yl]methanylyl-idene})bis-[1,1-diphenyl-N-(tri-methyl-sil-yl)-λ(5)-phosphanamine] pentane disolvate

The title compound, C62H78N4P4Se2Si4·2C5H12, is made up of two [SeC(PPh2NSiMe3)(PPh2NHSiMe3)] units related by an inversion center situated at the mid-point of the diselenide bond. It crystallized with two disordered mol-ecules of pentane used as solvent of crystallization. It is a rare example of an anti-periplanar diselenide and exhibits a long Se-Se bond of 2.4717 (8) Å. The Se-C bond length of 1.876 (5) Å is short in comparison with the range of values found for other diselenides (1.91-1.97 Å). The mol-ecule exhibits two intra-molecular N-H⋯N hydrogen bonds. In the crystal, there are no significant inter-molecular inter-actions present. One of the Me3Si- groups is disordered over two positions with a refined occupancy ratio of 0.708 (8):0.292 (8). The contribution of the disordered solvent to the scattering was removed with the SQUEEZE option of PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155]. The solvent contribution has been included in the reported mol-ecular weight and density.

Homoleptic, heteroleptic and mixed-valent thallium and indium complexes of multidentate chalcogen-centred PCP-bridged ligands

The metathetical reaction of [Li(TMEDA)][HC(PPh(2)Se)(2)] ([Li(TMEDA)]1) with TlOEt in a 1:1 molar ratio afforded a homoleptic Tl(I) complex as an adduct with LiOEt, Tl[HC(PPh(2)Se)(2)]·LiOEt (7), which undergoes selenium-proton exchange upon mild heating (60 °C) to give the mixed-valent Tl(I)/Tl(III) complex {[Tl][Tl{(Se)C(PPh(2)Se)(2)}(2)]}(∞) (8). Treatment of TlOEt with [Li(TMEDA)](2)[(SPh(2)P)(2)CE'E'C(PPh(2)S)(2)] (3b, E' = S; 3c, E' = Se) in a 2:1 molar ratio produced the binuclear Tl(i)/Tl(i) complexes Tl(2)[(SPh(2)P)(2)CE'E'C(PPh(2)S)(2)] (9b, E' = S; 9c, E' = Se), respectively. Selenium-proton exchange also occurred upon addition of [Li(TMEDA)]1 to InCl(3) to yield the heteroleptic complex (TMEDA)InCl[(Se)C(PPh(2)Se)(2)] (10a). Other examples of this class of In(III) complex, (TMEDA)InCl[(E')C(PPh(2)E)(2)] (10b, E = E' = S; 10c, E = S, E' = Se) were obtained via metathesis of InCl(3) with [Li(TMEDA)](2)[(E')C(PPh(2)E)(2)] (2b, E = E' = S; 2c, E = S, E' = Se, respectively). All new compounds have been characterized in solution by (1)H and (31)P NMR spectroscopy and the solid-state structures have been determined for 8, 9c and 10a-c by single-crystal X-ray crystallography. Complex 8 is comprised of Tl(+) ions that are weakly coordinated to octahedral [Tl{(Se)C(PPh(2)Se)(2)}(2)](-) anions to give a one-dimensional polymer. The complex 9c is comprised of two four-coordinate Tl(+) ions that are each S,S',S'',Se bonded to the hexadentate [(SPh(2)P)(2)CSeSeC(PPh(2)S)(2)](2-) ligand in which d(Se-Se) = 2.531(2) Å. The six-coordinate In(III) centres in the distorted octahedral complexes 10a-c are connected to a tridentate [(E')C(PPh(2)E)(2)](2-) dianion, a chloride ion and a neutral bidentate TMEDA ligand.