Di(benzothiazol-2-yl)phosphanide as a Janus-head ligand to caesium.

Starting from tris(benzothiazol-2-yl)phosphane (1) an advanced Janus-head ligand, di(benzothiazol-2-yl)phosphane (2), was synthesised and structurally characterised. The heteroaryl substituents of this ligand provide both hard and soft donor sites. Surprisingly, the phosphorus atom in 2 is divalent and the hydrogen atom is directly bonded to one ring nitrogen atom and hydrogen bonded to the second. Compound 2 decomposes in any common solvent other than diethyl ether and a new preparation to improve the yields of 2 is presented. A coordination polymer, [{Cs(bth)(2)P}8] (3) (bth=benzothiazol-2-yl), was obtained when the sec-phosphane 2 was allowed to react with elemental caesium in a 1:1 ratio in diethyl ether at -78 degrees C. In 3 each anion is coordinated to four caesium cations and vice versa. The central phosphorus atom is coordinated to two metal atoms above and below the mean plane of the anion in positions in which the two lone pairs of a four-electron donor are anticipated. Two additional cations micro-bridge both ring nitrogen atoms. Hence both faces of the Janus-head ligand are coordinated to the same number of metal cations but in a different way.

The P(bth)2- anion as a Janus head staple between lithium and manganese (bth = benzothiazol-2-yl, C7H4NS).

Deprotonation of HP(bth)2 (1) affords the lithium phosphanide [(Et2O)2Li(bth)2P], (2) with both nitrogen atoms coordinated to the lithium atom while in the heterobimetallic complex [Li(bth)2P{Mn(CO)2Cp}2](n) (3) additionally the phosphorus atom micro-bridges two Mn(CO)2Cp residues.

From the tetra(amino) phosphonium cation, [P(NHPh)4]+, to the tetra(imino) phosphate trianion, [P(NPh)4]3-, two-faced ligands that bind anions and cations.

The tetraanilino phosphonium cation, [P(N(H)Ph)4]+, 1+, is sequentially deprotonated by Bu(n)Li in thf. The deprotonation reaction of the chloride derivative, Cl, was monitored by (31)P NMR, which revealed the successive formation of the neutral [P(N(H)Ph)3(NPh)], 2, the monoanionic [P(N(H)Ph)2(NPh)2]-, 3-, the dianionic [P(N(H)Ph)(NPh)3]2-, 4(2-), and finally the trianionic species [P(NPh)(4)](3-), (3-). Considering the isoelectronic relationship of oxo, =O, and imino groups, =NR, as well as hydroxy, -OH, and amino groups, -N(H)R, the neutral complex corresponds to phosphoric acid, H3PO4, whereas the anions 3-, 4(2-) and 5(3-) are analogues of dihydrogen phosphate, H2PO4-, monohydrogenphosphate, HPO4(2-), and orthophosphate ions, PO4(3-), respectively. Solid state structures were obtained of 1Cl, 2LiCl(thf)(2), 3Li(thf)(3.5), 3Li(2)Cl(thf)(4.25), 3Li(2)Cl(thf)(6) and 5Li(4)Cl(thf)(4). All systems provide two separate N-P-N chelation sites at opposite ligand faces, either consisting of the di(amino) arrangement P(NH)(2), acting as a double H-bond donor, the di(imino) arrangement PN(2), donating two electron pairs, or the mixed amino imino arrangement P(N)(NH), which supplies both electron pair and H-donor site. Interesting in this aspect is the mixed amino imino derivative 3- which has the ability to chelate a Lewis acid, such as a metal ion, at one face and a Lewis base, such as an anionic or neutral donor at the opposite ligand face. The formation of 1-D aggregates and the entrapment of lithium chloride are key characteristics of the supramolecular structures of the discussed complexes.

Efficient stereoselective synthesis of novel steroid-polyquinane hybrids.

A synthesis of steroid-polyquinane hybrids, a new class of molecular entities, is described. [reaction: see text]