Abstract: A “bridged” bis-cyclopentadienyl complex which can be advantageously used for the formation of a catalytic system active in the (co)polymerization of ethylene and other &agr;-olefins is represented by means of the following formula (II): wherein: M represents a metal selected from titanium, zirconium or hafnium; A′ and A″ each independently represent an anion containing an &eegr;5-cyclopentadienyl ring coordinated to M; R′ or R″ each independently represents a group of an anionic nature &sgr;-bound to the metal M; B represents an unsaturated bivalent organic residue having from 1 to 30 carbon atoms, bound, respectively, to the ring of group A′ and to the —CH2-methylene group by means of carbon atoms.

Abstract: A “bridged” bis-cyclopentadienyl complex which can be advantageously used for the formation of a catalytic system active in the (co)polymerization of ethylene and other a-olefins is represented by means of the following formula (II): 1

Abstract: A catalytic composition effective in the selective hydrogenation of olefinic double bonds, comprising the reaction product between: (A) at least one complex of a transition metal having the following general formula (I): M(R1)(R2)(R3)(R4)  (I)  wherein: M is selected from titanium and zirconium, preferably titanium; each of the radicals R1, R2, R3 or R4, independently, represents an organic or inorganic group of an anionic nature &sgr;-bound to M, on the condition that at least one, and preferablyat at least two, of these radicals is an organic group; and (B) at least one organometallic compound of magnesium having the following formula (II): Mg(R5)n(R6)(2−n)  (II)  wherein: R5 or R6 each independently represent an aliphatic or aromatic hydrocarbon group having from 1 to 20 carbon atoms, and “n” is a decimal number between 0 and 2.0.

Abstract: A “bridged” bis-cyclopentadienyl complex which can be advantageously used for the formation of a catalytic system active in the (co)polymerization of ethylene and other &agr;-olefins is represented by means of the following formula (II): wherein: M represents a metal selected from titanium, zirconium or hafnium; A′ and A″ each independently represent an anion containing an &eegr;5-cyclopentadienyl ring coordinated to M; R′ or R″ each independently represents a group of an anionic nature a-bound to the metal M; B represents an unsaturated bivalent organic residue having from 1 to 30 carbon atoms, bound, respectively, to the ring of group A′ and to the —CH2— methylene group by means of carbon atoms.

Abstract: Effective catalyst in the selective hydrogenation of olefinic double bonds, comprising the reaction product between: (A) at least one cyclopentadienyl complex of a transition metal having the following general formula (I): (R)M(R1)(R2)(R3)  (I)  wherein: M is selected from titanium, zirconium and hafnium, preferably titanium; R is an anion containing an &eegr;5-cyclopentadienyl ring co-ordinated to M; and each R1, R2 or R3, independently, represents an organic or inorganic group of an anionic nature bound to M, and may, particularly, be hydride, halide, a C1-C8 alkyl group, a C3-C12 alkylsilyl group, a C5-C8 cycloalkyl group, a C6-C10 aryl group, a C1-C8 alkoxyl group, a C1-C8 carboxyl group, a C2-C10 dialkylamide group and a C4-C20 alkylsilylamide group;  the above compound (I) being solid, supported or dispersed in an inert liquid medium; and (B) at least one organometallic compound of magnesium having the following formula (II): Mg(R4)n(R5)(2−n)  (II)  whe

Abstract: Phosphino oxide group containing compounds useful as flame retardant additives, having the general formula (I): ##STR1## wherein: X and X.sub.1 represent a hydrogen atom or, when taken jointly, they represent an NR.sub.1 moiety in which R.sub.1 stands for a hydrogen atom; a linear or branched aliphatic C.sub.1 -C.sub.5 moiety; a linear or branched C.sub.2 -C.sub.6 acyl moiety; a phenyl moiety;R represents a cyclic or polycyclic C.sub.4 -C.sub.9 moiety containing two carboxy groups, possibly esterified with univalent alcohols or glycols, or transformed into anhydrides, or two hydroxy groups.