Reaction of Pentelidene Complexes with Diazoalkanes: Stabilization of Parent 2,3‐Dipnictabutadienes

Abstract

The reaction of the phosphinidene complex [Cp*P{W(CO) 5 } 2 ]( 1a)w ith diphenyldiazomethane leads to [{W(CO) 5 }Cp*P=NN{W(CO) 5 }=CPh 2 ]( 2). Compound 2 is ar are example of ap hosphadiazadiene ligand (R-P = N À N = CR'R'')c omplex. At temperatures above08 8C, 2 decomposes into the complex [{W(CO) 5 }PCp*{N(H)N = CPh 2 ) 2 ]( 3), among other species.The reaction of the pentelidene complexes [Cp*E{W(CO) 5 } 2 ]( E= P, As) with diazomethane (CH 2 NN) proceeds differently.For the arsinidene complex (1b), only the arsaalkene complex 4b [{W(CO) 5 } 2 {h 1:2 -(Cp*)As=CH 2 }] is formed. The reaction with the phosphinidene complex (1a) results in three products,t he two phosphaalkene complexes [{W(CO) 5 } 2 {h 1:2 -(R)P = CH 2 }] (4a:R= Cp*, 5:R= H) and the triazaphosphole derivative [{W(CO) 5 }P(Cp*)-CH 2 -N{W-(CO) 5 }=N-N(N=CH 2 )] (6a). The phosphaalkene complex (4a)a nd the arsaalkene complex (4b)a re not stable at room temperature and decompose to the complexes [{W(CO) 5 } 4 (CH 2 = E À E = CH 2 )] (7a:E = P, 7b:E = As), which are the first examples of complexes with parent 2,3diphospha-1,3-butadiene and 2,3-diarsa-1,3-butadiene ligands.

P–N and N–Mo Bond Formation Processes in the Reactions of a Pyramidal Phosphinidene-Bridged Dimolybdenum Complex with Diazoalkanes and Organic Azides

“…60 o with respect to the Mo2PN plane, thus completing a distorted trigonal bipyramidal (TBP) environment around the P atom, as found in the mentioned derivatives of 1. This local geometry around phosphorus has been also found in different derivatives of the trigonal phosphinidene complex [Mo2Cp{- 1 : 1 , 5 -PC5H4}( 6 -HMes*)(CO)2] with carbene, 7 chalcogens, 14 alkynes, 15 and metal carbonyl fragments 16 added at the MoP multiple bond of this substrate, although in these cases steric effects seem to play a significant role too. We further note that the P atom in compounds 2b and 3 bridges the Mo atoms in a symmetrical way (MoP lengths ca.…”

“…Scheer et al also found that reactions of [W2(-PCp*)(CO)10] with diazoalkanes can lead to phosphadiazadiene-or phosphaalkene-bridged derivatives, depending on the particular reagent used (N2CPh2 vs. N2CH2), although additional products were observed in the reaction with diazomethane. 5 In contrast, reaction of this ditungsten complex with azides N3R (R = Hex, Cy) proceeded selectively without denitrogention to yield triazaphosphete-bridged complexes (Scheme 2), which model the intermediate species proposed for the Staudinger reaction. 6 Scheme 2.…”