SYNTHESIS AND CHARACTERISATION OF A NElW MIXED (Si(IV), AI(HI)) p-0X0-ISOPROPOXIDE AND ITS ACID COMPLEXEtS

R RAMACHANDRAN, B. SINGH, A. K. NARULA, P. N. KAPOOR, P. K. GUPTA and R N. KAPOOR* Department of Chemistry, University of Delhi, Delhi-7, India (Received 4 January 1984; aeeepted after reuision 10 October 1984) Abstract-Reaction of dimethyldiacetoxysilane with aluminium isopropoxide was carried out in 1: 2 molar ratio in refluxing cyclohexane and a mixed [Si(IV), Al(III)J /~-0x0- isopropoxide of the composition Me,SiOzAI,(OPr’), was isolated. This compound was characterised by elemental analysis and IR and NMR spectral studies. The tertiary butanol derivative, Me~SiO~Al~(O3u~~, was prepared by alcoholysis. Reactions of this mixed [Si(Iv), A&III)] p-oxo-isopropoxide with monobasic bidentate carboxylic acids, such as tram- cinnamic acid (HCA) and dihydro~nnamic acid (HDCA) and with dibasic tridentate carboxylic acids such as salicylic acid (H,SA) and benzilic acid (H,BA) were also studied. Products of the type Me,SiO,Al,(OPr~,_,(L), [where HL = trans-cinnamic acid (HCA), dihydrocinnamic acid (HDCA) and n = 1,2,3 or 41 and Me,SiO,Al,(OPr’),_In(L)n [where H,L = salicylic acid (H,SA), benzilic acid (H,BA) and n = 1 or 23 were isolated and characterised by elemental and spectral studies. Metal siloxides have aroused considerable interest in recent years because of their applicability in the synthesis of polymeric substances.’ Synthesis of alkoxy siloxy derivatives’ of aluminiypl has been reported by Mehrotra and Pant’ starting with tr~ethyla~toxysilane and ~umi~um isopro- poxide. Preparation of poly~uminoorganosilo- xanes reported by Zudanov and Andrianov3 involves the interaction of aluminium butoxide and dialkyldiacetoxysilane. Reactions of alkylacetoxy- silanes with aluminium isopropoxide were carried out by Yasuaki Nakaido4 and Sugio Otani et aL5 and the compounds so prepared were used for polymer preparation under the name “inorganic polymers”. Literature survey reveals that there is no report on the synthesis of mixed [Si(Iv), Al(III)] ~-0x0- isopropoxide. It was therefore, considered of interest to synthesise this mixed [Si(IV), Al (III)] ~-0x0- isopropoxide by reacting dimethyldia~toxysilane with ~umi~um isopropoxide in 1: 2 molar ratio in refluxing cyclohexane. The reaction can be repre- sented as follows