[en] In this Thesis new molecular and supramolecular species of Pd (II) and Pt (II) have been prepared: on the one hand, we synthesized Pt (II) complexes derived from hydrazone ligands, and on the other hand, we prepared rectangular metallacycles derived of N-monoalkyl-4,4'-bipyridinium and Pd (II) and Pt (II) metal centres, containing in their structure the carbene 1,1'-di (methyl) -3,3 methylene-4-diimidazole- 2,2'-ylidene. We observed that the reactivity of the N-phenylhydrazones a-d (a= 2-Cl-C6H4N(H)N=CMe(C5H4N); b= 3-Cl-C6H4N(H)N=CMe(C5H4N); c= 2,4-Cl-C6H3N(H)N=CMe(C5H4N); d= C6H5N(H)N=CMe(C5H4N)) versus K2PtCl4 in n-butanol/water at 100 °C depends on the substitution of the phenyl ring. Thus, when the hydrazones a and d reacted the mononuclear coordination complexes 1a and 1d are obtained, with the hydrazone ligands acting as bidentates [N, N] chelate. However, the reaction of the hydrazones c and d with K2PtCl4, under analogous reaction conditions, leads directly to the formation of the cyclometallated species 2b and 2c. When the coordination compounds 1a and 1d are treated with sodium acetate in n-butanol at 100 °C, the cyclometallated compounds 2a and 2d were obtained after activation of the C-H bond. DFT calculations were carried out in an attempt to understand the different reactivity of the ligands, studying the possible mechanism of the reaction of these ligands with K2PtCl4, which suggests that the formation of the cyclometallated species takes place through a mechanism of the aromatic electrophilic substitution, so that the substitution in the phenolic ring greatly affects to the reactivity of the C-H bond for the formation of the corresponding cyclometallated compound. On the other hand, it was determined that the presence of acetate in the reaction medium favours the deprotonation of N-H and facilitates electrophilic activation of the C-H bond. Although calculations determine that the most stable species are the coordination complexes, the formation of cyclometallates can be justified by the solvation energy of the HCl in the solvent or the neutralization with the base, which shifts the equilibrium towards the formation of the cyclometallated species. The ligand hydrazone e (3,4-Me2- C6H2C(Me)=NN(H)(4'-Cl-C4H2N2)) undergoes the same reaction and leads the cyclometallated specie 1e, which was carried out a study of its reactivity to different tertiary phosphines, leading to the production of new mononuclear and trinuclear complexes. The crystal structure obtained by X-ray diffraction of two of these complexes, shows interesting p-p interactions between chelate rings and aromatic rings. It was possible to obtain M2L2 dinuclear metallocyclic receptors, with square and rectangular shape, in water from ligands derived of N-monoalkyl-4,4'-bipyridinium and metal centers of Pd (II) and Pt (II), which contain in their structure a chelate carbene ligand. After the preparation of the metallocycles, the ability of these metal corners to perform the exchange of pyridine ligands was studied and on the other hand, a conformational study of this carbenes was carried out, through the formation of complexes with 2,2'-pyridine and 2,2'-bipyrimidine ligands and their modelling by DFT calculations. Due to the strong trans effect exerted by the carbene ligands, the synthesis of the Pt2L2 receptors was achieved as well by self-assembly of the components at room temperature in few hours, in clear contraposition to the harsh reaction conditions usually required for the labialization of other kinetically inert Pt(II)-N(pyridine) bonds. X-ray diffraction studies of suitable single crystals of two of the obtained receptors offered additional information on the structure of the obtained supramolecules, which ability as receptors has been explored by the preparation of the corresponding inclusion complexes in water with 1,5- dihydroxinaphthalene as model substrate.

[gl] Na presente Tese de Doutoramento preparáronse novas especies moleculares e supramoleculares de Pd(II) e Pt(II): por unha banda sintetizáronse complexos de Pt(II) derivados de ligandos hidrazonas, e por outra banda, preparáronse autoensamblados dinucleares de xeometría cadrada e rectangular derivados de N-monoalquil-4,4'-bipiridinio e centros metálicos de Pd(II) e Pt(II), que conteñen na súa estrutura o ligando quelato carbeno 1,1'-di(metil)-3,3'-metilen-4-diimidazol-2,2'-ilideno. Observouse que a reactividade das N-fenilhidrazonas a-d (a= 2-Cl-C6H4N(H)N=CMe(C5H4N); b= 3-Cl- C6H4N(H)N=CMe(C5H4N); c= 2,4-Cl-C6H3N(H)N=CMe(C5H4N); d= C6H5N(H)N=CMe(C5H4N)) fronte a K2PtCl4 en n-butanol/agua a 100 °C depende da substitución do grupo fenilo. Deste xeito, cando se fan reaccionar as hidrazonas a e d obtéñense os complexos de coordinación mononucleares 1a e 1d cos ligandos hidrazona actuando como bidentados quelato [N,N]. Non obstante, a reacción das hidrazonas b e c con K2PtCl4, en condicións de reacción análogas, conduce directamente á formación das especies ciclometaladas 2b e 2c. Cando os compostos de coordinación 1a e 1d se tratan con acetato sódico en n-butanol a 100 °C, obtéñense os correspondentes compostos ciclometalados 2a e 2d despois da activación do enlace C-H. A través de cálculos DFT intentamos comprender a diferente reactividade dos ligandos a-d, estudando o posible mecanismo de reacción dos mesmos con K2PtCl4, o cal suxire que a formación do ciclometalado ten lugar a través dun mecanismo de substitución electrófila aromática, polo que a sustitución que presenta o anel fenílico, afecta enormemente á reactividade do mesmo fronte á activación do enlace C-H para a formación do ciclometalado correspondente. Por outra banda, determinouse que a presenza de acetato no medio de reacción, favorece a desprotonación do N-H e facilita a activación electrofílica C-H. Aínda que os cálculos determinan que a especie máis estable son os complexos de coordinación, a formación dos ciclometalados pode xustificarse pola enerxía de solvatación do HCl no disolvente ou de neutralización coa base, a cal despraza o equilibrio cara a formación dos ciclometalados. O ligando hidrazona e (3,4-Me2-C6H2C(Me)=NN(H)(4'-Cl-C4H2N2)) experimenta a reacción de ciclometalación conducindo á obtención da especie ciclometalada 1e, da cal se estudou a súa reactividade fronte a diferentes fosfinas terciarias, conducindo á obtención de novos complexos mononucleares e trinucleares. A estrutura cristalina obtida por difracción de raios X de dous destes complexos, mostra interesantes interaccións p-p entre aneis quelato e aneis aromáticos. Foi posible obter receptores metalocíclicos dinucleares M2L2 de xeometría cadrada e rectangular en auga a partir de ligandos derivados de N-monoalquil-4,4'-bipiridinio e centros metálicos de Pd(II) e Pt(II), que conteñen na súa estrutura ligandos quelato carbeno. Previa á preparación dos metalociclos, estudouse, por unha parte, a aptitude destas esquinas metálicas para levar a cabo o intercambio de ligandos piridínicos, e por outro lado, levouse a cabo un estudio conformacional das mesmas, a través da formación de complexos cos ligandos 2,2'-piridina e 2,2'-bipirimidina e da súa modelización mediante cálculos DFT. No caso dos derivados metalocíclicos Pd2L2, estes foron preparados e caracterizados por RMN en medio acuoso e foi posible comprobar que presentan especiación dependente da súa concentración en disolución. Por outra banda, e en clara contraposición ás condicións de reacción enérxicas requiridas usualmente para a formación de metalociclos debido á inercia dos enlaces Pt(II)-N(Py), a síntese dos metalociclos Pt2L2 levouse a cabo mediante a autoensamblaxe dos compoñentes de partida a temperatura ambiente en poucas horas, debido ao forte efecto trans exercido polo ligando carbeno. Estudos de difracción de raios X de monocristal de dous dos receptores obtidos proporcionaron información adicional da estrutura de ditas supramoléculas, cuxa capacidade como receptores foi explorada mediante a preparación e estudio dos correspondentes complexos de inclusión en auga, empregando 1, 5- dihidroxinaftaleno como modelo de substrato.