Darstellung und Eigenschaften von und Reaktionen mit metallhaltigen Heterocyclen, LXXVII Synthese, Struktur und Reaktivität von Phosphametallacyclopropanen mit isolobalen ER‐ (E = N, P, As, Sb) und Fe(CO)₄‐Bausteinen

Abstract

The phosphidometallates Liz{ [M]"PPh,) {[MI = (q5-C5H5)M-(CO),), resulting from the metal hydride complexes H[M]PPh,H [M = Cr (11, Mo (21, W (3)] by reduction with nBuLi, react with the geminal dihalides REClz to give the three-membered phosphametallacyclopropanes [ M -R [ER = NC6F5 (M = Cr (la), Mo (2a), W (3a)), PPh (M=Cr (lb), Mo (2b), W (3b)), PC6HII (M=Cr (lc), Mo (2c), W (3c)), P-tBu (M=Cr (ld), Mo (2d), W (3d)), P(2,4,6-(tB~)~C&~) (M=Cr (le), Mo (Ze), W (3e)), As(2,4,6-(tB~)~C~H~) (M= Cr ( l f ) , Mo (2f), W (3f)), Sb-tBu (M=Cr (lg), Mo (2g))l. Reaction of Br,Fe(CO), with the corresponding dilithium compounds Li,([M]=PPh,] affords the phosphido-bridged heterodimetallic complexes [ M m e -(CO), [M= Cr (lh), Mo (2h), W (3h)j. According to X-ray structural analyses in 2a and 2f the P -E bond distances are shortened while the Mo -E bonds are significantly elongated compared to a single bond. (OC)5CrTHF is added to the Lewis basic E atom in 2b, 2d, and 2g with loss of THF to give [ M m R C r ( C O ) 5 [ER=PPh (4b), P-tBu (4d), Sb-tBu (4g)l.By this reaction the antimony-containing ring 2g is kinetically stabilized. Because of the low basicity of the N atom in 2a no addition was observed. The ring skeleton of 4b and 4g, undergoes no change by Cr(CO)5 coordination as shown by Xray structural analyses.

Reversal of polarization in amidophosphines: neutral- and anionic-κP coordination vs. anionic-κP,N coordination and the formation of nickelaazaphosphiranes

“…Syntheses and structures of 5 and 6 were previously communicated. 25 The difunctional ligands in these complexes can create both structural and analytical problems and to simplify the coordination chemistry of these heterocycles we replaced one of the PN(H)Bu t groups of 1 with a Me 2 Si group to obtain the diazaphosphasiletidine {Me 2 Si(l-NBu t ) 2 PN(H)Bu t } (7). 26 This silicon-phosphorus-nitrogen compound retains the essential structure of the phosphorus-nitrogen ligands, namely a phosphorus(III) atom incorporated in a heterocycle and flanked by two sp 2 -hybridized nitrogen atoms.…”

“…Indeed, the metalaazaphosphirane moiety in the 18-electron complex [(g 5 -C 5 H 5 )(CO) 2 Mo(Ph 2 PNC 6 F 5 )], F, is closer to those of the title compounds. 7 For example, the phosphorus-nitrogen bond is 1.640(3) A ˚long, while the molybdenum-phosphorus and molybdenum-nitrogen bonds are 2.362(2) and 2.239(3) A ˚long, respectively. But even if corrections are made for the approximately 0.15 A ˚larger covalent radius of molybdenum, versus nickel, the endocyclic bonds in F are still almost 0.1 A ˚longer.…”

“…The ambidentate amidophosphines have been shown to chelate metals through either nitrogen (jN), 4 phosphorus (jP) 5 or through both atoms simultaneously (jP,N). [6][7][8] Depending on one's inclination the bis(tert-butylamino)diazadiphosphetidine 1 (Chart 1) may be regarded as either a cyclic diphosphine or a cyclic tetraamine. 9 In the former role this heterocycle had garnered some attention as neutral phosphorus-donor ligand for transition metals.…”