Azo-phosphine containing complexes of Group 6 metal carbonyls:: crystal and molecular structure of [Mo(CO)5{1-(4-ethylphenylazo)-6-diphenylphosphino-naphthalen-2-ol}]

Treatment of the compounds [M(CO)(5)(NCMe)] (M = Cr, Mo, W) with the phenylazonaphthylphosphines 4-R-PhN2-1-C10H5- 2-OR'-6-PPh2 {R' = H, R = H (1), R = Me (II), R = Et (III), R = Pr-i (IV) R = Bu-t (V); R' = C(O)Me, R = Me (VI)} afforded the mono-substituted products [M(CO)(5)(L)] (1-8) (M = Cr, L = II, 1; M = Mo, L = I-VI, 2-7; M = W, L = II, 8). Further reaction of cis-[Mo(CO)(4)(piperidine)(2)] with the azo-phosphines I-V afforded the di-substituted complexes cis-[Mo(CO)(4)(L)(2)] (9-13); whereas, reaction with VI afforded cis-[Mo(CO)(4)(II)(2)] rather than the expected compound cis-[Mo(CO)(4)(VI)(2)] (14). 14 can, however, be prepared by esterification of 10. The observed non-innocence of piperidene on displacement from cis[Mo(CO)(4)(piperidine)(2)] has been further investigated. Thus, treatment of 7 with piperidene yielded 3 as a result it becomes apparent that the potential reactivity of the displaced ligand needs to be considered carefully when carrying out simple substitution reactions. The molecular structure of 4 is also reported. (C) 1998 Elsevier Science S.A. All rights reserved.