Antimony as a symmetrically bridged ligand in a novel neutral complex

Abstract

[LWNSbNWL] 7 (L = N(CH 2 CH 2 N(Np)) 3 ; Np = CH 2 CMe 3 ) is prepared by treatment of [LWCl] 5 with LiSb(SiMe 3 ) 2 -(dme) n ; the ethylene complex [LWCl(C 2 H 4 )] 6 is a side product in the synthesis of 5; all complexes are structurally characterised.Complexes of the general formula [L n M·E] (E = P, As) with terminal ligands represent a new class of compounds. 6 While complex 5 dissolves well in toluene and is moderately soluble in pentane, compound 6 undergoes decomposition even in solvents of low polarity, resulting in the formation of an insoluble solid which could not be characterised. In the mass spectra of 5 and 6 the peaks for the molecular ions are observed. The 1 H NMR spectrum of 5 reveals broad signals at high and low field for the paramagnetic d 2 -tungsten complex. †The source of the ethylene in 6 is uncertain. It is possibly a result of a fragmentation of the tren ligand itself. Schrock and co-workers observed C-N bond cleavage of the ligand framework of a tren complex of tantalum, yielding a N-allyl unit. 7 Moreover, the low yields generally observed in the reactions of chlorotungsten(IV) complexes with tren ligands indicate various side reactions during the synthesis. 8 In the structure of the trigonal bipyramidal tungsten complex 5 the W-Cl and the W-N ax distances [2.389(2) and 2.179(5) Å] are only slightly shorter than the equivalent distances [2.399(2) and 2.182(6) Å] in the isostructural Me 3 Si substituted complex 4. ‡ In 6 (Fig.

Antimony–Tungsten Triple Bond: A Stable Complex with a Terminal Antimony Ligand

“…[16] The main feature of the structure of 6 (Figure 1) is a terminally coordinated antimony ligand. The observed WÀSb distance in 6 of 2.5255 (17) is the shortest reported to date, consistent with the representation as a triple bond, and is comparable only with the WÀSb distances in the heterocumulene complexes [{N(CH 2 CH 2 NR) 3 W} 2 Sb] (2.5275(5) R = iPr; [13] 2.574(1) R = CH 2 C(CH 3 ) 3 [14] ). Longer W-Sb bonds were observed in the stibinidene complexes [{(OC) 5 W} 2 SbCl(thf)] (2.662(1) and 2.670(2) ) [19] and [{(OC) 5 W} 2 SbCH(SiMe 3 ) 2 ] (2.687(1) ).…”

“…[13,14] Now we have finally succeeded in the synthesis and spectroscopic and structural characterization of the first isolable stibido complex [(N 3 N)W Sb] (6) which contains an antimony-tungsten triple bond.…”

Highlights in the Renaissance of Amidometal Chemistry

“…If a RN 3 N anion (R neopentyl) is used as ligand a compound is isolated in which the antimony atom acts as a symmetrical bridge between two tungsten centers (Scheme 55). [235] Scheme 55. Antimony as a bridging ligand.…”

Highlights der Renaissance der Amidometallchemie

“…Verwendet man das RN 3 N-Anion (R Neopentyl) als Ligand, wird eine Verbindung isoliert, in der ein Antimonatom als symmetrische Brücke zwischen zwei Wolframzentren fungiert (Schema 55). [235] Schema 55. Antimon als Brückenligand.…”